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Ebert A, Dahley C. Can membrane permeability of zwitterionic compounds be predicted by the solubility-diffusion model? Eur J Pharm Sci 2024; 199:106819. [PMID: 38815700 DOI: 10.1016/j.ejps.2024.106819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 04/23/2024] [Accepted: 05/27/2024] [Indexed: 06/01/2024]
Abstract
Zwitterions contain both positively and negatively charged functional groups, resulting in an overall net neutral charge. Nevertheless, the membrane permeability of the zwitterionic form of a compound is assumed to be much lower than the permeability of the uncharged neutral form. Although a significant proportion of pharmaceuticals are zwitterionic, it has not been clear so far whether their permeability is dominated by the permeation of the zwitterionic or the neutral form, since neutral fractions are often quite low as compared to the zwitterionic fraction. This complicates the in silico prediction of the permeability of zwitterionic compounds. In this work, we re-evaluated existing in vitro permeability data from literature measured with Caco-2/MDCK cell assays, using more strict exclusion criteria for effects like diffusion limitation by the aqueous boundary layers, paracellular transport, active transport and retention. Using this re-evaluated data set, we show that extracted intrinsic permeabilities of the neutral fraction are well predicted by the solubility-diffusion model (RMSE = 1.21; n = 18) if the permeability of the zwitterionic species is assumed negligible. Our work thus suggests that only the neutral species is relevant for the membrane permeability of zwitterionic compounds, and that membrane permeability of zwitterionic compounds is indeed predictable by the solubility-diffusion model.
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Affiliation(s)
- Andrea Ebert
- Department of Computational Biology & Chemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, 04318 Leipzig, Germany.
| | - Carolin Dahley
- Department of Computational Biology & Chemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, 04318 Leipzig, Germany
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2
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Maculewicz J, Białk-Bielińska A, Kowalska D, Stepnowski P, Stolte S, Beil S, Gajewicz-Skretna A, Dołżonek J. Bioconcentration potential of ionic liquids: New data on membrane partitioning and its comparison with predictions obtained by COSMOmic. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184320. [PMID: 38583701 DOI: 10.1016/j.bbamem.2024.184320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 03/19/2024] [Accepted: 04/01/2024] [Indexed: 04/09/2024]
Abstract
Ionic liquids (ILs) have recently gained significant attention in both the scientific community and industry, but there is a limited understanding of the potential risks they might pose to the environment and human health, including their potential to accumulate in organisms. While membrane and storage lipids have been considered as primary sorption phases driving bioaccumulation, in this study we used an in vitro tool known as solid-supported lipid membranes (SSLMs) to investigate the affinity of ILs to membrane lipid - phosphatidylcholine and compare the results with an existing in silico model. Our findings indicate that ILs may have a strong affinity for the lipids that form cell membranes, with the key factor being the length of the cation's side chain. For quaternary ammonium cations, increase in membrane affinity (logMA) was observed from 3.45 ± 0.06 at 10 carbon atoms in chain to 4.79 ± 0.06 at 14 carbon atoms. We also found that the anion can significantly affect the membrane partitioning of the cation, even though the anions themselves tend to have weaker interactions with phospholipids than the cations of ILs. For 1-methyl-3-octylimidazolium cation the presence of tricyanomethanide anion caused increase in logMA to 4.23 ± 0.06. Although some of our data proved to be consistent with predictions made by the COSMOmic model, there are also significant discrepancies. These results suggest that further research is needed to improve our understanding of the mechanisms and structure-activity relationships involved in ILs bioconcentration and to develop more accurate predictive models.
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Affiliation(s)
- Jakub Maculewicz
- Department of Environmental Analysis, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Anna Białk-Bielińska
- Department of Environmental Analysis, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Dorota Kowalska
- Department of Environmental Analysis, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Piotr Stepnowski
- Department of Environmental Analysis, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Stefan Stolte
- Institute of Water Chemistry, TU Dresden, 01062 Dresden, Germany
| | - Stephan Beil
- Institute of Water Chemistry, TU Dresden, 01062 Dresden, Germany
| | - Agnieszka Gajewicz-Skretna
- Laboratory of Environmental Chemoinformatics, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Joanna Dołżonek
- Department of Environmental Analysis, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland.
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3
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Ebert A, Dahley C, Goss KU. Pitfalls in evaluating permeability experiments with Caco-2/MDCK cell monolayers. Eur J Pharm Sci 2024; 194:106699. [PMID: 38232636 DOI: 10.1016/j.ejps.2024.106699] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 01/05/2024] [Accepted: 01/08/2024] [Indexed: 01/19/2024]
Abstract
When studying the transport of molecules across biological membranes, intrinsic membrane permeability (P0) is more informative than apparent permeability (Papp), because it eliminates external (setup-specific) factors, provides consistency across experiments and mechanistic insight. It is thus an important building block for modeling the total permeability in any given scenario. However, extracting P0 is often difficult, if not impossible, when the membrane is not the dominant transport resistance. In this work, we set out to analyze Papp values measured with Caco-2/MDCK cell monolayers of 69 literature references. We checked the Papp values for a total of 318 different compounds for the extractability of P0, considering possible limitations by aqueous boundary layers, paracellular transport, recovery issues, active transport, a possible proton flux limitation, and sink conditions. Overall, we were able to extract 77 reliable P0 values, which corresponds to about one quarter of the total compounds analyzed, while about half were limited by the diffusion through the aqueous layers. Compared to an existing data set of P0 values published by Avdeef, our approach resulted in a much higher exclusion of compounds. This is a consequence of stricter compound- and reference-specific exclusion criteria, but also because we considered possible concentration-shift effects due to different pH values in the aqueous layers, an effect only recently described in literature. We thus provide a consistent and reliable set of P0, e.g. as a basis for future modeling.
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Affiliation(s)
- Andrea Ebert
- Department of Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, Leipzig 04318, Federal Republic of Germany.
| | - Carolin Dahley
- Department of Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, Leipzig 04318, Federal Republic of Germany
| | - Kai-Uwe Goss
- Department of Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research (UFZ), Permoserstraße 15, Leipzig 04318, Federal Republic of Germany; Institute of Chemistry, University of Halle-Wittenberg, Kurt-Mothes-Straße 2, Halle 06120, Federal Republic of Germany
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4
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Antle JP, LaRock MA, Falls Z, Ng C, Atilla-Gokcumen GE, Aga DS, Simpson SM. Building Chemical Intuition about Physicochemical Properties of C8-Per-/Polyfluoroalkyl Carboxylic Acids through Computational Means. ACS ES&T ENGINEERING 2023; 4:196-208. [PMID: 38860110 PMCID: PMC11164130 DOI: 10.1021/acsestengg.3c00267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2024]
Abstract
We have predicted acid dissociation constants (pK a), octanol-water partition coefficients (K OW), and DMPC lipid membrane-water partition coefficients (K lipid-w) of 150 different eight-carbon-containing poly-/perfluoroalkyl carboxylic acids (C8-PFCAs) utilizing the COnductor-like Screening MOdel for Realistic Solvents (COSMO-RS) theory. Different trends associated with functionalization, degree of fluorination, degree of saturation, degree of chlorination, and branching are discussed on the basis of the predicted values for the partition coefficients. In general, functionalization closest to the carboxylic headgroup had the greatest impact on the value of the predicted physicochemical properties.
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Affiliation(s)
- Jonathan P Antle
- Department of Chemistry, University at Buffalo, the State University of New York (SUNY), Buffalo, New York 14260, United States
| | - Michael A LaRock
- Department of Chemistry, St. Bonaventure University, St. Bonaventure, New York 14778, United States
| | - Zackary Falls
- Department of Biomedical Informatics, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203, United States
| | - Carla Ng
- Department of Civil & Environmental Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - G Ekin Atilla-Gokcumen
- Department of Chemistry, University at Buffalo, the State University of New York (SUNY), Buffalo, New York 14260, United States
| | - Diana S Aga
- Department of Chemistry, University at Buffalo, the State University of New York (SUNY), Buffalo, New York 14260, United States
| | - Scott M Simpson
- Department of Chemistry, St. Bonaventure University, St. Bonaventure, New York 14778, United States
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5
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Köhler HR, Gräff T, Schweizer M, Blumhardt J, Burkhardt J, Ehmann L, Hebel J, Heid C, Kundy L, Kuttler J, Malusova M, Moroff FM, Schlösinger AF, Schulze-Berge P, Panagopoulou EI, Damalas DE, Thomaidis NS, Triebskorn R, Maletzki D, Kühnen U, von der Ohe PC. LogD-based modelling and ΔlogD as a proxy for pH-dependent action of ionizable chemicals reveal the relevance of both neutral and ionic species for fish embryotoxicity and possess great potential for practical application in the regulation of chemicals. WATER RESEARCH 2023; 235:119864. [PMID: 36944304 DOI: 10.1016/j.watres.2023.119864] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 02/19/2023] [Accepted: 03/09/2023] [Indexed: 06/18/2023]
Abstract
Depending on the ambient pH, ionizable substances are present in varying proportions in their neutral or charged form. The extent to which these two chemical species contribute to the pH-dependant toxicity of ionizable chemicals and whether intracellular ion trapping has a decisive influence in this context is controversially discussed. Against this background, we determined the acute toxicity of 24 ionizable substances at up to 4 different pH values on the embryonic development of the zebrafish, Danio rerio, and supplemented this dataset with additional data from the literature. The LC50 for some substances (diclofenac, propranolol, fluoxetine) differed by a factor of even >103 between pH5 and pH9. To simulate the toxicity of 12 acids and 12 bases, six models to calculate a pH-dependant logD value as a proxy for the uptake of potentially toxic molecules were created based on different premises for the trans-membrane passage and toxic action of neutral and ionic species, and their abilities to explain the real LC50 data set were assessed. Using this approach, we were able to show that both neutral and charged species are almost certainly taken up into cells according to their logD-based distribution, and that both species exert toxicity. Since two of the models that assume all intracellular molecules to be neutral overestimated the real toxicity, it must be concluded, that the toxic effect of a single charged intracellularly present molecule is, on the average, lower than that of a single neutral molecule. Furthermore, it was possible to attribute differences in toxicity at different pH values for these 24 ionizable substances to the respective deltas in logD at these pH levels with high accuracy, enabling particularly a full logD-based model on the basis of logPow as a membrane passage descriptor to be used for predicting potential toxicities in worst-case scenarios from existing experimental studies, as stipulated in the process of registration of chemicals and the definition of Environmental Quality Standards (EQS).
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Affiliation(s)
- Heinz-R Köhler
- Animal Physiological Ecology, Institute of Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 5, Tübingen D-72076, Germany.
| | - Thomas Gräff
- Federal Environment Agency, Wörlitzer Platz 1, Dessau-Roßlau D-06844, Germany
| | - Mona Schweizer
- Animal Physiological Ecology, Institute of Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 5, Tübingen D-72076, Germany
| | - Jasmin Blumhardt
- Animal Physiological Ecology, Institute of Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 5, Tübingen D-72076, Germany
| | - Jasmin Burkhardt
- Animal Physiological Ecology, Institute of Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 5, Tübingen D-72076, Germany
| | - Lisa Ehmann
- Animal Physiological Ecology, Institute of Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 5, Tübingen D-72076, Germany
| | - Janine Hebel
- Animal Physiological Ecology, Institute of Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 5, Tübingen D-72076, Germany
| | - Christoph Heid
- Animal Physiological Ecology, Institute of Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 5, Tübingen D-72076, Germany
| | - Lone Kundy
- Animal Physiological Ecology, Institute of Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 5, Tübingen D-72076, Germany
| | - Julia Kuttler
- Animal Physiological Ecology, Institute of Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 5, Tübingen D-72076, Germany
| | - Miroslava Malusova
- Animal Physiological Ecology, Institute of Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 5, Tübingen D-72076, Germany
| | - Friederike-Marie Moroff
- Animal Physiological Ecology, Institute of Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 5, Tübingen D-72076, Germany
| | - Anne-Frida Schlösinger
- Animal Physiological Ecology, Institute of Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 5, Tübingen D-72076, Germany
| | - Pia Schulze-Berge
- Animal Physiological Ecology, Institute of Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 5, Tübingen D-72076, Germany
| | - Eleni I Panagopoulou
- Department of Chemistry, Laboratory of Analytical Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, Athens GR-15771, Greece
| | - Dimitrios E Damalas
- Department of Chemistry, Laboratory of Analytical Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, Athens GR-15771, Greece
| | - Nikolaos S Thomaidis
- Department of Chemistry, Laboratory of Analytical Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou, Athens GR-15771, Greece
| | - Rita Triebskorn
- Animal Physiological Ecology, Institute of Evolution and Ecology, University of Tübingen, Auf der Morgenstelle 5, Tübingen D-72076, Germany; Steinbeis-Transfer Center Ecotoxicology and Ecophysiology, Blumenstrasse 13, Rottenburg D-72108, Germany
| | - Dirk Maletzki
- Federal Environment Agency, Schichauweg 58, Berlin D-12307, Germany
| | - Ute Kühnen
- Federal Environment Agency, Wörlitzer Platz 1, Dessau-Roßlau D-06844, Germany
| | - Peter C von der Ohe
- Federal Environment Agency, Wörlitzer Platz 1, Dessau-Roßlau D-06844, Germany.
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6
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Potter TD, Haywood N, Teixeira A, Hodges G, Barrett EL, Miller MA. Partitioning into phosphatidylcholine-cholesterol membranes: liposome measurements, coarse-grained simulations, and implications for bioaccumulation. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2023. [PMID: 37158124 DOI: 10.1039/d3em00081h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Membrane-water partitioning is an important physical property for the assessment of bioaccumulation and environmental impact. Here, we advance simulation methodology for predicting the partitioning of small molecules into lipid membranes and compare the computational predictions to experimental measurements in liposomes. As a step towards high-throughput screening, we present an automated mapping and parametrization procedure to produce coarse-grained models compatible with the Martini 3 force field. The methodology is general and can also be used for other applications where coarse-grained simulations are appropriate. This article addresses the effect on membrane-water partitioning of adding cholesterol to POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) membranes. Nine contrasting neutral, zwitterionic and charged solutes are tested. Agreement between experiment and simulation is generally good, with the most challenging cases being permanently charged solutes. For all solutes, partitioning is found to be insensitive to membrane cholesterol concentration up to 25% mole fraction. Hence, for assessment of bioaccumulation into a range of membranes (such as those found in fish), partitioning data measured in pure lipid membranes are still informative.
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Affiliation(s)
- Thomas D Potter
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom.
| | - Nicola Haywood
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, United Kingdom
| | - Alexandre Teixeira
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, United Kingdom
| | - Geoff Hodges
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, United Kingdom
| | - Elin L Barrett
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, United Kingdom
| | - Mark A Miller
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom.
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7
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Balk F, Hollender J, Schirmer K. Investigating the bioaccumulation potential of anionic organic compounds using a permanent rainbow trout liver cell line. ENVIRONMENT INTERNATIONAL 2023; 174:107798. [PMID: 36965398 DOI: 10.1016/j.envint.2023.107798] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 02/01/2023] [Accepted: 02/01/2023] [Indexed: 06/18/2023]
Abstract
Permanent rainbow trout (Oncorhynchus mykiss) cell lines represent potential in vitro alternatives to experiments with fish. We here developed a method to assess the bioaccumulation potential of anionic organic compounds in fish, using the rainbow trout liver-derived RTL-W1 cell line. Based on the availability of high quality in vivo bioconcentration (BCF) and biomagnification (BMF) data and the substances' charge state at physiological pH, four anionic compounds were selected: pentachlorophenol (PCP), diclofenac (DCF), tecloftalam (TT) and benzotriazol-tert-butyl-hydroxyl-phenyl propanoic acid (BHPP). The fish cell line acute toxicity assay (OECD TG249) was used to derive effective concentrations 50 % and non-toxic exposure concentrations to determine exposure concentrations for bioaccumulation experiments. Bioaccumulation experiments were performed over 48 h with a total of six time points, at which cell, medium and plastic fractions were sampled and measured using high resolution tandem mass spectrometry after online solid phase extraction. Observed cell internal concentrations were over-predicted by KOW-derived predictions while pH-dependent octanol-water partitioning (DOW) and membrane lipid-water partitioning (DMLW) gave better predictions of cell internal concentrations. Measured medium and cell internal concentrations at steady state were used to calculate RTL-W1-based BCF, which were compared to DOW- or DMLW-based model approaches and in vivo data. With the exception of PCP, the cell-derived BCF best compared to DOW-based model predictions, which were higher than predictions based on DMLW. All methods predicted the in vivo BCF for diclofenac well. For PCP, the cell-derived BCF was lowest although all BCF predictions underestimated the in vivo BCF by ≥ 1 order of magnitude. The RTL-W1 cells, and all other prediction methods, largely overestimated in vivo BMF, which were available for PCP, TT and BHPP. We conclude that the RTL-W1 cell line can supplement BCF predictions for anionic compounds. For BMF estimations, however, in vitro-in vivo extrapolations need adaptation or a multiple cell line approach.
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Affiliation(s)
- Fabian Balk
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; EPF Lausanne, School of Architecture, Civil and Environmental Engineering, 1015 Lausanne, Switzerland
| | - Juliane Hollender
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; ETH Zürich, Department of Environmental Systems Science, 8092 Zürich, Switzerland
| | - Kristin Schirmer
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; EPF Lausanne, School of Architecture, Civil and Environmental Engineering, 1015 Lausanne, Switzerland; ETH Zürich, Department of Environmental Systems Science, 8092 Zürich, Switzerland.
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8
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Droge STJ, Hodges G, Bonnell M, Gutsell S, Roberts J, Teixeira A, Barrett EL. Using membrane-water partition coefficients in a critical membrane burden approach to aid the identification of neutral and ionizable chemicals that induce acute toxicity below narcosis levels. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2023; 25:621-647. [PMID: 36779707 DOI: 10.1039/d2em00391k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The risk assessment of thousands of chemicals used in our society benefits from adequate grouping of chemicals based on the mode and mechanism of toxic action (MoA). We measure the phospholipid membrane-water distribution ratio (DMLW) using a chromatographic assay (IAM-HPLC) for 121 neutral and ionized organic chemicals and screen other methods to derive DMLW. We use IAM-HPLC based DMLW as a chemical property to distinguish between baseline narcosis and specific MoA, for reported acute toxicity endpoints on two separate sets of chemicals. The first set comprised 94 chemicals of US EPA's acute fish toxicity database: 47 categorized as narcosis MoA, 27 with specific MoA, and 20 predominantly ionic chemicals with mostly unknown MoA. The narcosis MoA chemicals clustered around the median narcosis critical membrane burden (CMBnarc) of 140 mmol kg-1 lipid, with a lower limit of 14 mmol kg-1 lipid, including all chemicals labelled Narcosis_I and Narcosis_II. This maximum 'toxic ratio' (TR) between CMBnarc and the lower limit narcosis endpoint is thus 10. For 23/28 specific MoA chemicals a TR >10 was derived, indicative of a specific adverse effect pathway related to acute toxicity. For 10/12 cations categorized as "unsure amines", the TR <10 suggests that these affect fish via narcosis MoA. The second set comprised 29 herbicides, including 17 dissociated acids, and evaluated the TR for acute toxic effect concentrations to likely sensitive aquatic plant species (green algae and macrophytes Lemna and Myriophyllum), and non-target animal species (invertebrates and fish). For 21/29 herbicides, a TR >10 indicated a specific toxic mode of action other than narcosis for at least one of these aquatic primary producers. Fish and invertebrate TRs were mostly <10, particularly for neutral herbicides, but for acidic herbicides a TR >10 indicated specific adverse effects in non-target animals. The established critical membrane approach to derive the TR provides for useful contribution to the weight of evidence to bin a chemical as having a narcosis MoA or less likely to have acute toxicity caused by a more specific adverse effect pathway. After proper calibration, the chromatographic assay provides consistent and efficient experimental input for both neutral and ionizable chemicals to this approach.
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Affiliation(s)
- Steven T J Droge
- Department of Freshwater and Marine Ecology (FAME), Institute for Biodiversity and Ecosystem Dynamics (IBED), Universiteit van Amsterdam (UvA), Science Park 904, 1098XH Amsterdam, The Netherlands.
| | - Geoff Hodges
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire, UK
| | - Mark Bonnell
- Environment and Climate Change Canada, Ecological Assessment Division, Science and Risk Assessment Directorate, Gatineau, Quebec, Canada
| | - Steve Gutsell
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire, UK
| | - Jayne Roberts
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire, UK
| | - Alexandre Teixeira
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire, UK
| | - Elin L Barrett
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire, UK
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9
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Zhu T, Yu Y, Tao T. A comprehensive evaluation of liposome/water partition coefficient prediction models based on the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method: Challenges from different descriptor dimension reduction methods and machine learning algorithms. JOURNAL OF HAZARDOUS MATERIALS 2023; 443:130181. [PMID: 36257111 DOI: 10.1016/j.jhazmat.2022.130181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 10/09/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
The liposome/water partition coefficient (Klip/w) is a key parameter to evaluate the bioaccumulation potential of pollutants. Considering that it is difficult to determine the Klip/w values of all pollutants through experiments, researchers gradually developed models to predict it. However, there is currently no research on how to comprehensively evaluate prediction models and recommend a compelling optimal modeling method. To remedy the defect of single parameters in a traditional model comparison, the TOPSIS evaluation method, based on entropy weight, was first proposed. We use this method to comprehensively evaluate models from multiple angles in this study. Thirty QSPR models, including 3 descriptor dimension reduction methods and 10 algorithms (belonging to 4 tribes), were used to predict Klip/w and verify the effectiveness of the comprehensive assessment method. The results showed that RF (descriptor dimension reduction method), symbolism (tribes) and RF (algorithm) exhibited significant advantages in establishing the Klip/w value prediction model. At present, the application of TOPSIS in environmental model evaluations is almost absent. We hope that the proposed TOPSIS evaluation method can be applied to more chemical datasets and provide a more systematic and comprehensive basis for the application of the QSPR model in environmental studies and other fields.
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Affiliation(s)
- Tengyi Zhu
- School of Environmental Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China.
| | - Yan Yu
- School of Environmental Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China
| | - Tianyun Tao
- College of Agriculture, Yangzhou University, Yangzhou 225009, Jiangsu, China
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10
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Nencini R, Ollila OHS. Charged Small Molecule Binding to Membranes in MD Simulations Evaluated against NMR Experiments. J Phys Chem B 2022; 126:6955-6963. [PMID: 36063117 PMCID: PMC9483918 DOI: 10.1021/acs.jpcb.2c05024] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Interactions of charged molecules with biomembranes regulate many of their biological activities, but their binding affinities to lipid bilayers are difficult to measure experimentally and model theoretically. Classical molecular dynamics (MD) simulations have the potential to capture the complex interactions determining how charged biomolecules interact with membranes, but systematic overbinding of sodium and calcium cations in standard MD simulations raises the question of how accurately force fields capture the interactions between lipid membranes and charged biomolecules. Here, we evaluate the binding of positively charged small molecules, etidocaine, and tetraphenylphosphonium to a phosphatidylcholine (POPC) lipid bilayer using the changes in lipid head-group order parameters. We observed that these molecules behave oppositely to calcium and sodium ions when binding to membranes: (i) their binding affinities are not overestimated by standard force field parameters, (ii) implicit inclusion of electronic polarizability increases their binding affinity, and (iii) they penetrate into the hydrophobic membrane core. Our results can be explained by distinct binding mechanisms of charged small molecules with hydrophobic moieties and monoatomic ions. The binding of the former is driven by hydrophobic effects, while the latter has direct electrostatic interactions with lipids. In addition to elucidating how different kinds of charged biomolecules bind to membranes, we deliver tools for further development of MD simulation parameters and methodology.
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Affiliation(s)
- Ricky Nencini
- Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - O H Samuli Ollila
- Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
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11
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Khawar MI, Mahmood A, Nabi D. Exploring the role of octanol-water partition coefficient and Henry's law constant in predicting the lipid-water partition coefficients of organic chemicals. Sci Rep 2022; 12:14936. [PMID: 36056200 PMCID: PMC9440013 DOI: 10.1038/s41598-022-19452-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 08/29/2022] [Indexed: 11/19/2022] Open
Abstract
Partition coefficients for storage lipid-water (logKlw) and phospholipid-water (logKpw) phases are key parameters to understand the bioaccumulation and toxicity of organic contaminants. However, the published experimental databases of these properties are dwarfs and current estimation approaches are cumbersome. Here, we present partition models that exploit the correlations of logKlw, and of logKpw with the linear combinations of the octanol-water partition coefficient (logKow) and the dimensionless Henry's law constant (air-water partition coefficient, logKaw). The calibrated partition models successfully describe the variations in logKlw data (n = 305, R2 = 0.971, root-mean-square-error (rmse) = 0.375), and in logKpw data (n = 131, R2 = 0.953, rmse = 0.413). With the inputs of logKow and logKaw estimated from the U.S. EPA's EPI Suite, our models of logKlw and logKpw have exhibited rmse = 0.52 with respect to experimental values indicating suitability of these models for inclusion in the EPI Suite. Our models perform similar to or better than the previously reported models such as one parameter partition models, Abraham solvation models, and models based on quantum-chemical calculations. Taken together, our models are robust, easy-to-use, and provide insight into variations of logKlw and logKpw in terms of hydrophobicity and volatility trait of chemicals.
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Affiliation(s)
- Muhammad Irfan Khawar
- Institute of Environmental Science and Engineering (IESE), School of Civil and Environmental Engineering (SCEE), National University of Sciences and Technology (NUST), Islamabad, H-12, Pakistan
- Environment and Agriculture Laboratory, School of Interdisciplinary Engineering and Sciences (SINES), National University of Sciences and Technology (NUST), Islamabad, H-12, Pakistan
| | - Azhar Mahmood
- School of Natural Sciences (SNS), National University of Sciences and Technology (NUST), Islamabad, H-12, Pakistan
| | - Deedar Nabi
- Institute of Environmental Science and Engineering (IESE), School of Civil and Environmental Engineering (SCEE), National University of Sciences and Technology (NUST), Islamabad, H-12, Pakistan.
- Environment and Agriculture Laboratory, School of Interdisciplinary Engineering and Sciences (SINES), National University of Sciences and Technology (NUST), Islamabad, H-12, Pakistan.
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12
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Antila HS, Kav B, Miettinen MS, Martinez-Seara H, Jungwirth P, Ollila OHS. Emerging Era of Biomolecular Membrane Simulations: Automated Physically-Justified Force Field Development and Quality-Evaluated Databanks. J Phys Chem B 2022. [DOI: 10.1021/acs.jpcb.2c01954] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Hanne S. Antila
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Batuhan Kav
- Institute of Biological Information Processing, Structural Biochemistry (IBI-7), Forschungszentrum
Jülich, Wilhelm-Johnen-Str., 52425 Jülich, Germany
| | - Markus S. Miettinen
- Computational Biology Unit, Department of Informatics, University of Bergen, 5008 Bergen, Norway
- Department of Chemistry, University of Bergen, 5020 Bergen, Norway
| | - Hector Martinez-Seara
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nam. 2, 16000 Prague 6, Czech Republic
| | - Pavel Jungwirth
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nam. 2, 16000 Prague 6, Czech Republic
| | - O. H. Samuli Ollila
- Institute of Biotechonology, University of Helsinki, Helsinki 00014, Finland
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13
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Katz SD, Chen H, Fields DM, Beirne EC, Keyes P, Drozd GT, Aeppli C. Changes in Chemical Composition and Copepod Toxicity during Petroleum Photo-oxidation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:5552-5562. [PMID: 35435676 DOI: 10.1021/acs.est.2c00251] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Photoproducts can be formed rapidly in the initial phase of a marine oil spill. However, their toxicity is not well understood. In this study, oil was irradiated, chemically characterized, and tested for toxicity in three copepod species (Acartia tonsa, Temora longicornis, and Calanus finmarchicus). Irradiation led to a depletion of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes in oil residues, along with an enrichment in aromatic and aliphatic oil photoproducts. Target lipid model-based calculations of PAH toxicity units predicted that PAH toxicities were lower in water-accommodated fractions (WAFs) of irradiated oil residues ("irradiated WAFs") than in WAFs of dark-control samples ("dark WAFs"). In contrast, biomimetic extraction (BE) measurements showed increased bioaccumulation potential of dissolved constituents of irradiated WAFs compared to dark WAFs, mainly driven by photoproducts present in irradiated oil. In line with the BE results, copepod mortality increased in irradiated WAFs compared to dark WAFs. However, low copepod toxicities were observed for WAFs produced with photo-oxidized oil slicks collected during the Deepwater Horizon oil spill. The results of this study suggest that while oil photoproducts have the potential to be a significant source of copepod toxicity, dilution and dispersion of these higher solubility products appear to help mitigate their toxicity at sea.
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Affiliation(s)
- Samuel D Katz
- Bigelow Laboratory for Ocean Sciences, East Boothbay, Maine 04544, United States
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882, United States
| | - Haining Chen
- Bigelow Laboratory for Ocean Sciences, East Boothbay, Maine 04544, United States
| | - David M Fields
- Bigelow Laboratory for Ocean Sciences, East Boothbay, Maine 04544, United States
- Colby College, Waterville, Maine 04901, United States
| | - Erin C Beirne
- Bigelow Laboratory for Ocean Sciences, East Boothbay, Maine 04544, United States
| | - Phoebe Keyes
- Bigelow Laboratory for Ocean Sciences, East Boothbay, Maine 04544, United States
| | - Greg T Drozd
- Colby College, Waterville, Maine 04901, United States
| | - Christoph Aeppli
- Bigelow Laboratory for Ocean Sciences, East Boothbay, Maine 04544, United States
- Colby College, Waterville, Maine 04901, United States
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14
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Brunetti G, Kodešová R, Švecová H, Fér M, Nikodem A, Klement A, Grabic R, Šimůnek J. A novel multiscale biophysical model to predict the fate of ionizable compounds in the soil-plant continuum. JOURNAL OF HAZARDOUS MATERIALS 2022; 423:127008. [PMID: 34844334 DOI: 10.1016/j.jhazmat.2021.127008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 08/06/2021] [Accepted: 08/20/2021] [Indexed: 06/13/2023]
Abstract
Soil pollution from emerging contaminants poses a significant threat to water resources management and food production. The development of numerical models to describe the reactive transport of chemicals in both soil and plant is of paramount importance to elaborate mitigation strategies. To this aim, in the present study, a multiscale biophysical model is developed to predict the fate of ionizable compound in the soil-plant continuum. The modeling framework connects a multi-organelles model to describe processes at the cell level with a semi-mechanistic soil-plant model, which includes the widely used Richards-based solver, HYDRUS. A Bayesian probabilistic framework is used to calibrate and assess the capability of the model in reproducing the observations from an experiment on the translocation of five pharmaceuticals in green pea plants. Results show satisfactory fitting performance and limited predictive uncertainty. The subsequent validation with the cell model indicates that the estimated soil-plant parameters preserve a physically realistic meaning, and their calibrated values are comparable with the existing literature values, thus confirming the overall reliability of the analysis. Model results further suggest that pH conditions in both soil and xylem play a crucial role in the uptake and translocation of ionizable compounds.
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Affiliation(s)
- Giuseppe Brunetti
- University of Natural Resources and Life Sciences, Vienna (BOKU), Institute for Soil Physics and Rural Water Management, Muthgasse 18, 1180 Vienna, Austria.
| | - Radka Kodešová
- Czech University of Life Sciences Prague, Faculty of Agrobiology, Food and Natural Resources, Dept. of Soil Science and Soil Protection, Kamýcká 129, CZ-16500 Prague 6, Czech Republic
| | - Helena Švecová
- University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Zátiší 728/II, CZ-38925 Vodňany, Czech Republic
| | - Miroslav Fér
- Czech University of Life Sciences Prague, Faculty of Agrobiology, Food and Natural Resources, Dept. of Soil Science and Soil Protection, Kamýcká 129, CZ-16500 Prague 6, Czech Republic
| | - Antonín Nikodem
- Czech University of Life Sciences Prague, Faculty of Agrobiology, Food and Natural Resources, Dept. of Soil Science and Soil Protection, Kamýcká 129, CZ-16500 Prague 6, Czech Republic
| | - Aleš Klement
- Czech University of Life Sciences Prague, Faculty of Agrobiology, Food and Natural Resources, Dept. of Soil Science and Soil Protection, Kamýcká 129, CZ-16500 Prague 6, Czech Republic
| | - Roman Grabic
- University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Zátiší 728/II, CZ-38925 Vodňany, Czech Republic
| | - Jiří Šimůnek
- University of California, Riverside, Department of Environmental Sciences, CA 92521, USA
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15
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Rokitskaya TI, Aleksandrova EV, Korshunova GA, Khailova LS, Tashlitsky VN, Luzhkov VB, Antonenko YN. Membrane Permeability of Modified Butyltriphenylphosphonium Cations. J Phys Chem B 2022; 126:412-422. [PMID: 34994564 DOI: 10.1021/acs.jpcb.1c08135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The alkyltriphenylphosphonium (TPP) group is the most widely used vector targeted to mitochondria. Previously, the length of the alkyl linker was varied as well as structural modifications in the TPP phenyl rings to obtain the optimal therapeutic effect of a pharmacophore conjugated with a lipophilic cation. In the present work, we synthesized butyltriphenylphosphonium cations halogenated and methylated in phenyl rings (C4TPP-X) and measured electrical current through a planar lipid bilayer in the presence of C4TPP-X. The permeability of C4TPP-X varied in the range of 6 orders of magnitude and correlates well with the previously measured translocation rate constant for dodecyltriphenylphosphonium analogues. The partition coefficient of the butyltriphenylphosphonium analogues obtained by calculating the difference in the free energy of cation solvation in water and octane using quantum chemical methods correlates well with the permeability values. Using an ion-selective electrode, a lower degree of accumulation of analogues with halogenated phenyl groups was found on isolated mitochondria of rat liver, which is in agreement with their permeability decrease. Our results indicate the translocation of the butyltriphenylphosphonium cations across the hydrophobic membrane core as rate-limiting stage in the permeability process rather than their binding/release to/from the membrane.
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Affiliation(s)
- Tatyana I Rokitskaya
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia
| | | | - Galina A Korshunova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Ljudmila S Khailova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Vadim N Tashlitsky
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Victor B Luzhkov
- Department of Kinetics of Chemical and Biological Processes, Institute of Problems of Chemical Physics, Russian Academy of Sciences, acad. Semenov av. 1, Chernogolovka, Moscow Region 142432, Russia.,Department of Fundamental Physical and Chemical Engineering, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Yuri N Antonenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia
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16
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Droge STJ, Scherpenisse P, Arnot JA, Armitage JM, McLachlan MS, Ohe PCVD, Hodges G. Screening the baseline fish bioconcentration factor of various types of surfactants using phospholipid binding data. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2021; 23:1930-1948. [PMID: 34787154 DOI: 10.1039/d1em00327e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Fish bioconcentration factors (BCFs) are commonly used in chemical hazard and risk assessment. For neutral organic chemicals BCFs are positively correlated with the octanol-water partition ratio (KOW), but KOW is not a reliable parameter for surfactants. Membrane lipid-water distribution ratios (DMLW) can be accurately measured for all kinds of surfactants, using phospholipid-based sorbents. This study first demonstrates that DMLW values for ionic surfactants are more than 100 000 times higher than the partition ratio to fish-oil, representing neutral storage lipid. A non-ionic alcohol ethoxylate surfactant showed almost equal affinity for both lipid types. Accordingly, a baseline screening BCF value for surfactants (BCFbaseline) can be approximated for ionic surfactants by multiplying DMLW by the phospholipid fraction in tissue, and for non-ionic surfactants by multiplying DMLW by the total lipid fraction. We measured DMLW values for surfactant structures, including linear and branched alkylbenzenesulfonates, an alkylsulfoacetate and an alkylethersulfate, bis(2-ethylhexyl)-surfactants (e.g., docusate), zwitterionic alkylbetaines and alkylamine-oxides, and a polyprotic diamine. Together with sixty previously published DMLW values for surfactants, structure-activity relationships were derived to elucidate the influence of surfactant specific molecular features on DMLW. For 23 surfactant types, we established the alkyl chain length at which BCFbaseline would exceed the EU REACH bioaccumulation (B) threshold of 2000 L kg-1, and would therefore require higher tier assessments to further refine the BCF estimate. Finally, the derived BCFbaseline are compared with measured literature in vivo BCF data where available, suggesting that refinements, most notably reliable estimates of biotransformation rates, are needed for most surfactant types.
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Affiliation(s)
- Steven T J Droge
- Institute for Biodiversity and Ecosystem Dynamics, Department Freshwater and Marine Ecology, University of Amsterdam, The Netherlands.
| | - Peter Scherpenisse
- Institute for Risk Assessment Sciences, Utrecht University, The Netherlands
| | - Jon A Arnot
- ARC Arnot Research and Consulting, Toronto, Ontario, Canada
| | | | | | | | - Geoff Hodges
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire, UK
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17
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Ebert A, Goss KU. Screening of 6000 Compounds for Uncoupling Activity: A Comparison Between a Mechanistic Biophysical Model and the Structural Alert Profiler Mitotox. Toxicol Sci 2021; 185:208-219. [PMID: 34865177 DOI: 10.1093/toxsci/kfab139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Protonophoric uncoupling of phosphorylation is an important factor when assessing chemicals for their toxicity, and has recently moved into focus in pharmaceutical research with respect to the treatment of diseases such as cancer, diabetes, or obesity. Reliably identifying uncoupling activity is thus a valuable goal. To that end, we screened more than 6000 anionic compounds for in vitro uncoupling activity, using a biophysical model based on ab initio COSMO-RS input parameters with the molecular structure as the only external input. We combined these results with a model for baseline toxicity (narcosis). Our model identified more than 1250 possible uncouplers in the screening dataset, and identified possible new uncoupler classes such as thiophosphoric acids. When tested against 423 known uncouplers and 612 known inactive compounds in the dataset, the model reached a sensitivity of 83% and a specificity of 96%. In a direct comparison, it showed a similar specificity than the structural alert profiler Mitotox (97%), but much higher sensitivity than Mitotox (47%). The biophysical model thus allows for a more accurate screening for uncoupling activity than existing structural alert profilers. We propose to use our model as a complementary tool to screen large datasets for protonophoric uncoupling activity in drug development and toxicity assessment.
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Affiliation(s)
- Andrea Ebert
- Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research-UFZ, D-04318 Leipzig, Germany
| | - Kai-Uwe Goss
- Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research-UFZ, D-04318 Leipzig, Germany.,Institute of Chemistry, Martin Luther University, D-06120 Halle, Germany
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18
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Ng C, Cousins IT, DeWitt JC, Glüge J, Goldenman G, Herzke D, Lohmann R, Miller M, Patton S, Scheringer M, Trier X, Wang Z. Addressing Urgent Questions for PFAS in the 21st Century. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:12755-12765. [PMID: 34519210 PMCID: PMC8590733 DOI: 10.1021/acs.est.1c03386] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Despite decades of research on per- and polyfluoroalkyl substances (PFAS), fundamental obstacles remain to addressing worldwide contamination by these chemicals and their associated impacts on environmental quality and health. Here, we propose six urgent questions relevant to science, technology, and policy that must be tackled to address the "PFAS problem": (1) What are the global production volumes of PFAS, and where are PFAS used? (2) Where are the unknown PFAS hotspots in the environment? (3) How can we make measuring PFAS globally accessible? (4) How can we safely manage PFAS-containing waste? (5) How do we understand and describe the health effects of PFAS exposure? (6) Who pays the costs of PFAS contamination? The importance of each question and barriers to progress are briefly described, and several potential paths forward are proposed. Given the diversity of PFAS and their uses, the extreme persistence of most PFAS, the striking ongoing lack of fundamental information, and the inequity of the health and environmental impacts from PFAS contamination, there is a need for scientific and regulatory communities to work together, with cooperation from PFAS-related industries, to fill in critical data gaps and protect human health and the environment.
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Affiliation(s)
- Carla Ng
- Departments of Civil & Environmental Engineering and Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA 15261 USA
| | - Ian T. Cousins
- Department of Environmental Science, Stockholm University, SE-10691 Stockholm, Sweden
| | - Jamie C. DeWitt
- Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC 27834 USA
| | - Juliane Glüge
- Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, 8092 Zürich, Switzerland
| | | | - Dorte Herzke
- Norwegian Institute for Air Research (NILU), Fram Centre, N-9296 Tromsø, Norway, and Institute for Arctic and Marine Biology, UiT The Arctic University of Norway, N-9037 TromsH, Norway
| | - Rainer Lohmann
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, USA
| | - Mark Miller
- National Institute of Environmental Health Science and U.S. Public Health Service, Research Triangle Park, NC 27709, USA
| | - Sharyle Patton
- Health and Environment Program, Commonweal, Bolinas, California 94924, United States
| | - Martin Scheringer
- Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, 8092 Zürich, Switzerland
- RECETOX, Masaryk University, 625 00 Brno, Czech Republic
| | - Xenia Trier
- European Environment Agency, Kgs Nytorv 6, DK - 1050 Copenhagen K, Denmark
| | - Zhanyun Wang
- Chair of Ecological Systems Design, Institute of Environmental Engineering, ETH Zürich, 8093 Zürich, Switzerland
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19
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Lee J, Braun G, Henneberger L, König M, Schlichting R, Scholz S, Escher BI. Critical Membrane Concentration and Mass-Balance Model to Identify Baseline Cytotoxicity of Hydrophobic and Ionizable Organic Chemicals in Mammalian Cell Lines. Chem Res Toxicol 2021; 34:2100-2109. [PMID: 34357765 DOI: 10.1021/acs.chemrestox.1c00182] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
All chemicals can interfere with cellular membranes and this leads to baseline toxicity, which is the minimal toxicity any chemical elicits. The critical membrane burden is constant for all chemicals; that is, the dosing concentrations to trigger baseline toxicity decrease with increasing hydrophobicity of the chemicals. Quantitative structure-activity relationships, based on hydrophobicity of chemicals, have been established to predict nominal concentrations causing baseline toxicity in human and mammalian cell lines. However, their applicability is limited to hydrophilic neutral compounds. To develop a prediction model that includes more hydrophobic and charged organic chemicals, a mass balance model was applied for mammalian cells (AREc32, AhR-CALUX, PPARγ-BLA, and SH-SY5Y) considering different bioassay conditions. The critical membrane burden for baseline toxicity was converted into nominal concentration causing 10% cytotoxicity by baseline toxicity (IC10,baseline) using a mass balance model whose main chemical input parameter was the liposome-water partition constants (Klip/w) for neutral chemicals or the speciation-corrected Dlip/w(pH 7.4) for ionizable chemicals plus the bioassay-specific protein, lipid, and water contents of cells and media. In these bioassay-specific models, log(1/IC10,baseline) increased with increasing hydrophobicity, and the relationship started to level off at log Dlip/w around 2. The bioassay-specific models were applied to 392 chemicals covering a broad range of hydrophobicity and speciation. Comparing the predicted IC10,baseline and experimental cytotoxicity IC10, known baseline toxicants and many additional chemicals were identified as baseline toxicants, while the others were classified based on specificity of their modes of action in the four cell lines, confirming excess toxicity of some fungicides, antibiotics, and uncouplers. Given the similarity of the bioassay-specific models, we propose a generalized baseline-model for adherent human cell lines: log[1/IC10,baseline (M)] = 1.23 + 4.97 × (1 - e-0.236 log Dlip/w). The derived models for baseline toxicity may serve for specificity analysis in reporter gene and neurotoxicity assays as well as for planning the dosing for cell-based assays.
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Affiliation(s)
- Jungeun Lee
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, DE-04318 Leipzig, Germany
| | - Georg Braun
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, DE-04318 Leipzig, Germany
| | - Luise Henneberger
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, DE-04318 Leipzig, Germany
| | - Maria König
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, DE-04318 Leipzig, Germany
| | - Rita Schlichting
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, DE-04318 Leipzig, Germany
| | - Stefan Scholz
- Department of Bioanalytical Toxicology, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, DE-04318 Leipzig, Germany
| | - Beate I Escher
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, DE-04318 Leipzig, Germany.,Environmental Toxicology, Center for Applied Geoscience, Eberhard Karls University Tübingen, Scharrenbergstrasse 94-96, DE-72076 Tübingen, Germany
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20
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Effective exposure of chemicals in in vitro cell systems: A review of chemical distribution models. Toxicol In Vitro 2021; 73:105133. [DOI: 10.1016/j.tiv.2021.105133] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 02/11/2021] [Accepted: 02/25/2021] [Indexed: 12/23/2022]
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21
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Lind C, Pandey P, Pastor RW, MacKerell AD. Functional Group Distributions, Partition Coefficients, and Resistance Factors in Lipid Bilayers Using Site Identification by Ligand Competitive Saturation. J Chem Theory Comput 2021; 17:3188-3202. [PMID: 33929848 DOI: 10.1021/acs.jctc.1c00089] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Small molecules such as metabolites and drugs must pass through the membrane of the cell, a barrier primarily comprising phospholipid bilayers and embedded proteins. To better understand the process of passive diffusion, knowledge of the ability of various functional groups to partition across bilayers and the associated energetics would be of utility. In the present study, the site identification by ligand competitive saturation (SILCS) methodology has been applied to sample the distributions of a diverse set of chemical solutes representing the functional groups of small molecules across phospholipid bilayers composed of 0.9:0.1 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine/cholesterol and a mixture of 0.52:0.18:0.3 1,2-dioleoyl-sn-glycero-3-phospho-l-serine/1,2-dioleoyl-sn-glycero-3-phosphocholine/cholesterol used in parallel artificial membrane permeability assay experiments. A combination of oscillating chemical potential grand canonical Monte Carlo and molecular dynamics in the SILCS simulations was applied to achieve solute sampling through the bilayers and surrounding aqueous environment from which the distribution of solutes and the functional groups they represent were obtained. Results show differential distribution of aliphatic versus aromatic groups with the former having increased sampling in the center of the bilayers versus in the region of the glycerol linker for the latter. Variations in the distribution of different polar groups are evident, with large differences between negative acetate and positive methylammonium with accumulation of the polar-neutral and acetate solutes above the bilayer head groups. Conversion of the distributions to absolute free energies allows for a detailed understanding of energetics of functional groups in different regions of the bilayers and for calculation of absolute free-energy profiles of multifunctional drug-like molecules across the bilayers from which partition coefficients and resistance factors suitable for insertion into the homogenous solubility-diffusion equation for calculation of permeability were obtained. Comparisons of the calculated bilayer/solution partition coefficients with 1-octanol/water experimental data for both drug-like molecules and the solutes show overall good agreement, validating the calculated distributions and associated absolute free-energy profiles.
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Affiliation(s)
- Christoffer Lind
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Baltimore, Maryland 21201, United States
| | - Poonam Pandey
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Baltimore, Maryland 21201, United States
| | - Richard W Pastor
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Alexander D MacKerell
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Baltimore, Maryland 21201, United States
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22
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Molecular simulations of lipid membrane partitioning and translocation by bacterial quorum sensing modulators. PLoS One 2021; 16:e0246187. [PMID: 33561158 PMCID: PMC7872223 DOI: 10.1371/journal.pone.0246187] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 01/15/2021] [Indexed: 12/18/2022] Open
Abstract
Quorum sensing (QS) is a bacterial communication process mediated by both native and non-native small-molecule quorum sensing modulators (QSMs), many of which have been synthesized to disrupt QS pathways. While structure-activity relationships have been developed to relate QSM structure to the activation or inhibition of QS receptors, less is known about the transport mechanisms that enable QSMs to cross the lipid membrane and access intracellular receptors. In this study, we used atomistic MD simulations and an implicit solvent model, called COSMOmic, to analyze the partitioning and translocation of QSMs across lipid bilayers. We performed umbrella sampling at atomistic resolution to calculate partitioning and translocation free energies for a set of naturally occurring QSMs, then used COSMOmic to screen the water-membrane partition and translocation free energies for 50 native and non-native QSMs that target LasR, one of the LuxR family of quorum-sensing receptors. This screening procedure revealed the influence of systematic changes to head and tail group structures on membrane partitioning and translocation free energies at a significantly reduced computational cost compared to atomistic MD simulations. Comparisons with previously determined QSM activities suggest that QSMs that are least likely to partition into the bilayer are also less active. This work thus demonstrates the ability of the computational protocol to interrogate QSM-bilayer interactions which may help guide the design of new QSMs with engineered membrane interactions.
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Escher BI, Neale PA. Effect-Based Trigger Values for Mixtures of Chemicals in Surface Water Detected with In Vitro Bioassays. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2021; 40:487-499. [PMID: 33252775 DOI: 10.1002/etc.4944] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 11/04/2020] [Accepted: 11/23/2020] [Indexed: 05/12/2023]
Abstract
Effect-based trigger (EBT) values for in vitro bioassays are important for surface water quality monitoring because they define the threshold between acceptable and poor water quality. They have been derived for highly specific bioassays, such as hormone-receptor activation in reporter gene bioassays, by reading across from existing chemical guideline values. This read-across method is not easily applicable to bioassays indicative of adaptive stress responses, which are triggered by many different chemicals, and activation of nuclear receptors for xenobiotic metabolism, to which many chemicals bind with rather low specificity. We propose an alternative approach to define the EBT from the distribution of specificity ratios of all active chemicals. The specificity ratio is the ratio between the predicted baseline toxicity of a chemical in a given bioassay and its measured specific endpoint. Unlike many previous read-across methods to derive EBTs, the proposed method accounts for mixture effects and includes all chemicals, not only high-potency chemicals. The EBTs were derived from a cytotoxicity EBT that was defined as equivalent to 1% of cytotoxicity in a native surface water sample. The cytotoxicity EBT was scaled by the median of the log-normal distribution of specificity ratios to derive the EBT for effects specific for each bioassay. We illustrate the new approach using the example of the AREc32 assay, indicative of the oxidative stress response, and 2 nuclear receptor assays targeting the peroxisome proliferator-activated receptor gamma and the arylhydrocarbon receptor. The EBTs were less conservative than previously proposed but were able to differentiate untreated and insufficiently treated wastewater from wastewater treatment plant effluent with secondary or tertiary treatment and surface water. Environ Toxicol Chem 2021;40:487-499. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
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Affiliation(s)
- Beate I Escher
- Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
- Center for Applied Geoscience, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Peta A Neale
- Australian Rivers Institute, School of Environment and Science, Griffith University, Southport, Queensland, Australia
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Henneberger L, Goss KU. Environmental Sorption Behavior of Ionic and Ionizable Organic Chemicals. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2021; 253:43-64. [PMID: 31748892 DOI: 10.1007/398_2019_37] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Traditionally our tools for environmental risk assessment of organic chemicals have been developed for neutral chemicals. However, many commercial chemicals are ionic or ionizable and require different tools and approaches for their assessment. In recent years this task starts to obtain increasing attention but our understanding for their environmental fate is still far behind that for neutral chemicals. This review first gives an overview on the principles that govern ionic partitioning in environmental systems which are more complex than the simple partition processes of neutral chemicals. Second, a summary of our current knowledge on various topics such as bioaccumulation, sorption in soils, and nonspecific-toxicity reveals that ionic species can actually be quite hydrophobic contrary to commonly held beliefs. Eventually, we discuss existing models for the quantitative prediction of organic ions' sorption in soils and biota. We have to assert that the available model tools are quite restricted in their application range compared to neutral chemicals which is due to the higher complexity of the various ionic sorption processes. In order to further advance our understanding more high-quality sorption data are needed with a focus on multivalent and zwitterionic ions in all partition systems as well as cations in biological matrices.
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Affiliation(s)
| | - Kai-Uwe Goss
- Helmholtz Centre for Environmental Research UFZ, Leipzig, Germany.
- Institute of Chemistry, University of Halle-Wittenberg, Halle, Germany.
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Ebert A, Goss KU. Predicting Uncoupling Toxicity of Organic Acids Based on Their Molecular Structure Using a Biophysical Model. Chem Res Toxicol 2020; 33:1835-1844. [PMID: 32462864 DOI: 10.1021/acs.chemrestox.0c00063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present a purely mechanistic model to predict protonophoric uncoupling activity ECw of organic acids. All required input information can be derived from their chemical structure. This makes it a convenient predictive model to gain valuable information on the toxicity of organic chemicals already at an early stage of development of new commercial chemicals (e.g., in agriculture or pharmaceutical industries). A critical component of the model is the consideration of the possible formation of heterodimers from the neutral and anionic monomer, and its permeation through the membrane. The model was tested against literature data measured in chromatophores, submitochondrial particles, isolated mitochondria, and intact green algae cells with good success. It was also possible to reproduce pH-dependencies in isolated mitochondria and intact cells. Besides the prediction of the ECw, the mechanistic nature of the model allows researchers to draw direct conclusions on the impact of single input factors such as pH- and voltage-gradients across the membrane, the anionic and neutral membrane permeability, and the heterodimerization constant. These insights are of importance in drug design or chemical regulation.
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Affiliation(s)
- Andrea Ebert
- Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research - UFZ, Leipzig 04318, Germany.,Institute of Biophysics, Johannes Kepler University, Linz 4020, Austria
| | - Kai-Uwe Goss
- Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research - UFZ, Leipzig 04318, Germany.,Institute of Chemistry, Martin Luther University, Halle 06120, Germany
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Grünewald F, Souza PCT, Abdizadeh H, Barnoud J, de Vries AH, Marrink SJ. Titratable Martini model for constant pH simulations. J Chem Phys 2020; 153:024118. [PMID: 32668918 DOI: 10.1063/5.0014258] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
In this work, we deliver a proof of concept for a fast method that introduces pH effects into classical coarse-grained (CG) molecular dynamics simulations. Our approach is based upon the latest version of the popular Martini CG model to which explicit proton mimicking particles are added. We verify our approach against experimental data involving several different molecules and different environmental conditions. In particular, we compute titration curves, pH dependent free energies of transfer, and lipid bilayer membrane affinities as a function of pH. Using oleic acid as an example compound, we further illustrate that our method can be used to study passive translocation in lipid bilayers via protonation. Finally, our model reproduces qualitatively the expansion of the macromolecule dendrimer poly(propylene imine) as well as the associated pKa shift of its different generations. This example demonstrates that our model is able to pick up collective interactions between titratable sites in large molecules comprising many titratable functional groups.
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Affiliation(s)
- Fabian Grünewald
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Paulo C T Souza
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Haleh Abdizadeh
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Jonathan Barnoud
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Alex H de Vries
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
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Ebert A, Allendorf F, Berger U, Goss KU, Ulrich N. Membrane/Water Partitioning and Permeabilities of Perfluoroalkyl Acids and Four of their Alternatives and the Effects on Toxicokinetic Behavior. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:5051-5061. [PMID: 32212724 DOI: 10.1021/acs.est.0c00175] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The search for alternatives to bioaccumulative perfluoroalkyl acids (PFAAs) is ongoing. New, still highly fluorinated alternatives are produced in hopes of reducing bioaccumulation. To better estimate this bioaccumulative behavior, we performed dialysis experiments and determined membrane/water partition coefficients, Kmem/w, of six perfluoroalkyl carboxylic acids (PFCAs), three perfluoroalkanesulfonic acids, and four alternatives. We also investigated how passive permeation might influence the uptake kinetics into cells, measuring the passive anionic membrane permeability Pion through planar lipid bilayers for six PFAAs and three alternatives. Experimental Kmem/w and Pion were both predicted well by the COSMO-RS theory (log RMSE 0.61 and 0.46, respectively). Kmem/w values were consistent with the literature data, and alternatives showed similar sorption behavior as PFAAs. Experimental Pion values were high enough to explain observed cellular uptake by passive diffusion with no need to postulate the existence of active uptake processes. However, predicted pKa and neutral permeabilities suggest that also the permeation of the neutral species should be significant in case of PFCAs. This can have direct consequences on the steady-state distribution of PFAAs across cell membranes and thus toxicity. Consequently, we propose a model to predict pH-dependent baseline toxicity based on Kmem/w, which considers the permeation of both neutral and anionic species.
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Affiliation(s)
- Andrea Ebert
- Department of Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, D-04318 Leipzig, Germany
- Institute of Biophysics, Johannes Kepler University, Gruberstrasse 40, 4020 Linz, Austria
| | - Flora Allendorf
- Department of Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, D-04318 Leipzig, Germany
| | - Urs Berger
- Department of Analytical Chemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, D-04318 Leipzig, Germany
| | - Kai-Uwe Goss
- Department of Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, D-04318 Leipzig, Germany
- Institute of Chemistry, University of Halle-Wittenberg, Kurt-Mothes-Strasse 2, D-06120 Halle, Germany
| | - Nadin Ulrich
- Department of Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, D-04318 Leipzig, Germany
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Schwöbel JAH, Ebert A, Bittermann K, Huniar U, Goss KU, Klamt A. COSMOperm: Mechanistic Prediction of Passive Membrane Permeability for Neutral Compounds and Ions and Its pH Dependence. J Phys Chem B 2020; 124:3343-3354. [DOI: 10.1021/acs.jpcb.9b11728] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
| | - Andrea Ebert
- UFZ—Helmholtz Centre for Environmental Research, Permoserstraße 15, D-04318 Leipzig, Germany
- Institute of Biophysics, Johannes Kepler University, Gruberstraße 40, 4020 Linz, Austria
| | - Kai Bittermann
- UFZ—Helmholtz Centre for Environmental Research, Permoserstraße 15, D-04318 Leipzig, Germany
| | - Uwe Huniar
- BIOVIA, Dassault Systèmes Deutschland GmbH, Imbacher Weg 46, D-51379 Leverkusen, Germany
| | - Kai-Uwe Goss
- UFZ—Helmholtz Centre for Environmental Research, Permoserstraße 15, D-04318 Leipzig, Germany
- Institute of Chemistry, University of Halle-Wittenberg, Kurt Mothes Str. 2, D-06120 Halle, Germany
| | - Andreas Klamt
- BIOVIA, Dassault Systèmes Deutschland GmbH, Imbacher Weg 46, D-51379 Leverkusen, Germany
- Institute of Physical and Theoretical Chemistry, University of Regensburg, Universitätsstraße 31, D-93053 Regensburg, Germany
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Escher BI, Abagyan R, Embry M, Klüver N, Redman AD, Zarfl C, Parkerton TF. Recommendations for Improving Methods and Models for Aquatic Hazard Assessment of Ionizable Organic Chemicals. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2020; 39:269-286. [PMID: 31569266 DOI: 10.1002/etc.4602] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 09/04/2019] [Accepted: 09/20/2019] [Indexed: 05/19/2023]
Abstract
Ionizable organic chemicals (IOCs) such as organic acids and bases are an important substance class requiring aquatic hazard evaluation. Although the aquatic toxicity of IOCs is highly dependent on the water pH, many toxicity studies in the literature cannot be interpreted because pH was not reported or not kept constant during the experiment, calling for an adaptation and improvement of testing guidelines. The modulating influence of pH on toxicity is mainly caused by pH-dependent uptake and bioaccumulation of IOCs, which can be described by ion-trapping and toxicokinetic models. The internal effect concentrations of IOCs were found to be independent of the external pH because of organisms' and cells' ability to maintain a stable internal pH milieu. If the external pH is close to the internal pH, existing quantitative structure-activity relationships (QSARs) for neutral organics can be adapted by substituting the octanol-water partition coefficient by the ionization-corrected liposome-water distribution ratio as the hydrophobicity descriptor, demonstrated by modification of the target lipid model. Charged, zwitterionic and neutral species of an IOC can all contribute to observed toxicity, either through concentration-additive mixture effects or by interaction of different species, as is the case for uncoupling of mitochondrial respiration. For specifically acting IOCs, we recommend a 2-step screening procedure with ion-trapping/QSAR models used to predict the baseline toxicity, followed by adjustment using the toxic ratio derived from in vitro systems. Receptor- or plasma-binding models also show promise for elucidating IOC toxicity. The present review is intended to help demystify the ecotoxicity of IOCs and provide recommendations for their hazard and risk assessment. Environ Toxicol Chem 2020;39:269-286. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.
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Affiliation(s)
- Beate I Escher
- Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
- Center for Applied Geoscience, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Ruben Abagyan
- Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
| | - Michelle Embry
- Health and Environmental Sciences Institute, Washington, DC, USA
| | - Nils Klüver
- Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | | | - Christiane Zarfl
- Center for Applied Geoscience, Eberhard Karls University of Tübingen, Tübingen, Germany
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Lin S, Yang X, Liu H. Development of liposome/water partition coefficients predictive models for neutral and ionogenic organic chemicals. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 179:40-49. [PMID: 31026749 DOI: 10.1016/j.ecoenv.2019.04.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 04/06/2019] [Accepted: 04/11/2019] [Indexed: 06/09/2023]
Abstract
Membrane/water partition coefficient (Km/w) is a vital parameter used to characterize the membrane permeability of compounds. Considering the Km/w value is difficult to observe experimentally for real biological membranes, liposome/water partition coefficient (Klip/w) is employed to approximate Km/w. Here, quantitative structure property relationship (QSPR) models for logKlip/w of the neutral organic chemicals and the neutral form of ionogenic organic chemicals (IOCs) (logKlip/w-neutral), ionic form of IOCs (logKlip/w-ionic), the speciation-corrected liposome-water distribution ratios at a pH = 7.40 (logDlip/w-(pH=7.40)) were developed. In the modeling, two modeling methods (multiple linear regressions (MLR) and k-nearest neighbor (kNN)) were used. The predictive variables employed here could be calculated from the molecular structure directly. For logKlip/w-neutral and logDlip/w-(pH=7.40), the logKOW and logDOW-based, non-logKOW and non-logDOW-based kNN-QSPR and MLR-QSPR models were developed, respectively. The evaluation results implied that the predictive performance of kNN-QSPR models is better than that of MLR-QSPR models. For logKlip/w-ionic, only one acceptable MLR-QSPR model was developed for cation and anion, respectively. The model quality of the derived models was evaluated following the OECD QSPR models validation guideline. The determination coefficient (R2), leave-one-out cross validation Q2 (Q2LOO) and bootstrapping coefficient (Q2BOOT), the external validation coefficient (Q2EXT) of all the models met the acceptable criteria (Q2 > 0.600, R2 > 0.700); while the root-mean-square error (RMSE) range from 0.351 to 0.857. All the results implied that the models had good goodness-of-fit, robustness and predictive ability. Therefore, the developed models could be used to fill the data gap for substances within the applicability domain on their missing logKlip/w-neutral, logKlip/w-ionic, logDlip/w-(pH=7.40) values.
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Affiliation(s)
- Shiyu Lin
- Key Laboratory of New Membrane Materials, Ministry of Industry and Information Technology, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Xianhai Yang
- Key Laboratory of New Membrane Materials, Ministry of Industry and Information Technology, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
| | - Huihui Liu
- Key Laboratory of New Membrane Materials, Ministry of Industry and Information Technology, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
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William N, Nelson A, Gutsell S, Hodges G, Rabone J, Teixeira A. Hg-supported phospholipid monolayer as rapid screening device for low molecular weight narcotic compounds in water. Anal Chim Acta 2019; 1069:98-107. [PMID: 31084746 DOI: 10.1016/j.aca.2019.04.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 04/04/2019] [Accepted: 04/09/2019] [Indexed: 11/27/2022]
Abstract
This study positions the fabricated Pt/Hg-supported phospholipid sensor element in the context of more conventional biomembrane-based screening platforms. The technology has been used together with immobilised artificial membrane (IAM) chromatography and COSMOmic simulation methods to screen the interaction of a series of low molecular weight narcotic organic compounds in water with phosphatidylcholine (PC) membranes. For these chemicals it is shown that toxicity to aquatic species is related to compound hydrophobicity which is associated with compound accumulation in the phospholipid membrane as modelled by IAM chromatography measurements and COSMOmic simulations. In contrast, the Hg-supported dioleoyl phosphatidylcholine (DOPC) sensor element records membrane damage/modification which is indirectly related to general toxicity and directly related to compound structure. Electrochemical limit of detection (LoD) values depend on molecular structure and range from 20 μmolL-1 for substituted phenols to 23 mmolL-1 for aliphatics. Rapid cyclic voltammetry (RCV) "fingerprints" showed that the major structural classes of compounds: alkyl/chlorobenzenes, substituted phenols, quaternary ammonium compounds and neutral amines interacted distinctively with the DOPC on Hg and that these observations correlated with and supported those predicted by the COSMOmic simulations of the compound/DMPC association. In addition, the compatibility of the electrochemical and COSMOmic methods validates the electrochemical device as a meaningful high throughput technology to screen compounds in water and report on the mechanistic details of their interaction with phospholipid layers.
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Affiliation(s)
- N William
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - A Nelson
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK.
| | - S Gutsell
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, UK
| | - G Hodges
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, UK
| | - J Rabone
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, UK
| | - A Teixeira
- Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, UK
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Mechanistic skin penetration model by the COSMOperm method: Routes of permeation, vehicle effects and skin variations in the healthy and compromised skin. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/j.comtox.2019.02.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Turchi M, Cai Q, Lian G. An evaluation of in-silico methods for predicting solute partition in multiphase complex fluids – A case study of octanol/water partition coefficient. Chem Eng Sci 2019. [DOI: 10.1016/j.ces.2018.12.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Dassuncao C, Pickard H, Pfohl M, Tokranov AK, Li M, Mikkelsen B, Slitt A, Sunderland EM. Phospholipid Levels Predict the Tissue Distribution of Poly- and Perfluoroalkyl Substances in a Marine Mammal. ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS 2019; 6:119-125. [PMID: 33283018 PMCID: PMC7713714 DOI: 10.1021/acs.estlett.9b00031] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Exposure to poly- and perfluoroalkyl substances (PFASs) has been linked to many negative health impacts in humans and wildlife. Unlike neutral hydrophobic organic pollutants, many PFASs are ionic and have been hypothesized to accumulate in both phospholipids and protein-rich tissues. Here we investigate the role of phospholipids for PFAS accumulation by analyzing associations among concurrent measurements of phospholipid, total protein, total lipid and 24 PFASs in the heart, muscle, brain, kidney, liver, blubber, placenta and spleen of North Atlantic pilot whales (Globicephala melas). The sum of 24 PFASs ( ∑ 24 PFAS ) was highest in the liver (median 260 ng g-1; interquartile range (IQR) 216-295 ng g-1) and brain (86.0; IQR 54.5-91.3 ng g-1), while phospholipid levels were highest in brain. The relative abundance of PFASs in the brain greatly increases with carbon chain lengths of 10 or greater, suggesting shorter-chained compounds may cross the blood-brain barrier less efficiently. Phospholipids were significant predictors of the tissue distribution of the longest-chained PFASs: perfluorodecanesulfonate (PFDS), perfluorododecanoate (PFDoA), perfluorotridecanoate (PFTrA), and perfluorotetradecanoic acid (PFTA) (rs = 0.5-0.6). In all tissues except the brain, each 1 mg g-1 increase in phospholipids led to a 12%-25% increase in the concentration of each PFAS. We conclude that partitioning to phospholipids is an important mechanism of bioaccumulation for long-chained PFASs in marine mammals.
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Affiliation(s)
- Clifton Dassuncao
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA 02138
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA, USA 02115
- Corresponding Author
| | - Heidi Pickard
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA 02138
| | - Marisa Pfohl
- Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, USA 02881
| | - Andrea K. Tokranov
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA 02138
| | - Miling Li
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA 02138
| | | | - Angela Slitt
- Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, USA 02881
| | - Elsie M. Sunderland
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA 02138
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA, USA 02115
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Klüver N, Bittermann K, Escher BI. QSAR for baseline toxicity and classification of specific modes of action of ionizable organic chemicals in the zebrafish embryo toxicity test. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2019; 207:110-119. [PMID: 30557756 DOI: 10.1016/j.aquatox.2018.12.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 12/03/2018] [Accepted: 12/04/2018] [Indexed: 05/06/2023]
Abstract
The fish embryo toxicity (FET) test with the zebrafish Danio rerio is widely used to assess the acute toxicity of chemicals thereby serving as animal alternative to the acute fish toxicity test. The minimal toxicity of neutral chemicals in the FET can be predicted with a previously published Quantitative Structure-Activity Relationship (QSAR) based on the liposome-water partition coefficient Klipw. Such a QSAR may serve to plan toxicity testing and to evaluate whether an observed effect is caused by a specific mode of action (MoA). The applicability domain of this QSAR was extended to ionizable organic chemicals (IOC) without any modification of slope and intercept simply by replacing the Klipw with the speciation-corrected liposome-water distribution ratio (Dlipw(pH)) as descriptor for the uptake into the embryo. FET LC50 values of IOCs were extracted from an existing FET database and published literature. IOCs were selected that are present concomitantly as neutral and charged, species, i.e., acids with an acidity constant pKa <10 and bases with pKa>5. IOCs were grouped according to their putative MoA of acute aquatic toxicity. The toxic ratios (TR) in the FET were derived by of the experimental FET-LC50 in comparison with the baseline toxicity QSAR. Baseline toxicants were confirmed to align well with the FET baseline toxicity QSAR (TR < 10). Chemicals identified to act as specific or reactive chemicals with the toxic ratio analysis in the FET test (TR > 10) were generally consistent with MoA classification for acute fish toxicity with a few exceptions that were suspected to have had issues with the stability of the pH during testing. One critical aspect for the effect analysis of ionizable chemicals is the pH, since the difference between pH and pKa determines the speciation and thereby the Dlipw(pH).
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Affiliation(s)
- Nils Klüver
- UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig, Germany.
| | - Kai Bittermann
- UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig, Germany
| | - Beate I Escher
- UFZ - Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig, Germany; Eberhard Karls University Tübingen, Center for Applied Geoscience, Environmental Toxicology Hölderlinstr. 12, 72074, Tübingen, Germany
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36
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Droge STJ. Membrane-Water Partition Coefficients to Aid Risk Assessment of Perfluoroalkyl Anions and Alkyl Sulfates. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:760-770. [PMID: 30572703 DOI: 10.1021/acs.est.8b05052] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
This study determined the sorption affinity to artificial phospholipid membranes ( KMW) for series of perfluorinated carboxylates (PFCAs), perfluorinated sulfonates (PFSAs), alkyl sulfates (C xSO4), and 1-alkanesulfonates (C xSO3). A sorbent dilution assay with solid supported lipid membranes (SSLM) showed consistent CF2 unit increments of 0.59, and CH2 unit increments of 0.53, for the log KMW of perfluorinated and hydrogenated anions, respectively. PFSAs sorbed 0.90 log units stronger than analogue PFCAs; C xSO4 sorbed 0.75 log units stronger than analogue C xSO3 anions. The log KMW values for the octyl analogues increase in the order H(CH2)8SO3- (1.74) < H(CH2)8SO4- (2.58) < F(CF2)8CO2- (PFNA, 4.04) < F(CF2)8SO3- (PFOS, 4.88). Intrinsic partition ratios determined on a phospholipid coated HPLC column (IAM-HPLC) closely aligned with SSLM KMW values. COSMO-RS based molecular calculations of KMW aligned with SSLM KMW values for hydrogenated anions with C8-C14 alkyl chains but strongly underestimated CF2 and CH2 unit increments for C4-C8 based anions. Dividing the critical narcotic membrane burden of 100 mmol/kg by the experimental KMW predicts lethal baseline toxicity concentrations (LC50,narc). The LC50,narc coincides with the lowest reported acute LC50 values for several anionic surfactants but were on average about an order of magnitude lower.
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Affiliation(s)
- Steven T J Droge
- Department of Freshwater and Marine Ecology (FAME), Institute for Biodiversity and Ecosystem Dynamics (IBED) , Universiteit van Amsterdam (UvA) , Science Park 904 , 1098XH Amsterdam , Netherlands
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37
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Klamt A, Schwöbel J, Huniar U, Koch L, Terzi S, Gaudin T. COSMOplex: self-consistent simulation of self-organizing inhomogeneous systems based on COSMO-RS. Phys Chem Chem Phys 2019; 21:9225-9238. [PMID: 30994133 DOI: 10.1039/c9cp01169b] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
During the past 20 years, the efficient combination of quantum chemical calculations with statistical thermodynamics by the COSMO-RS method has become an important alternative to force-field based simulations for the accurate prediction of free energies of molecules in liquid systems. While it was originally restricted to homogeneous liquids, it later has been extended to the prediction of the free energy of molecules in inhomogeneous systems such as micelles, biomembranes, or liquid interfaces, but these calculations were based on external input about the structure of the inhomogeneous system. Here we report the rigorous extension of COSMO-RS to a self-consistent prediction of the structure and the free energies of molecules in self-organizing inhomogeneous systems. This extends the application range to many new areas, such as the prediction of micellar structures and critical micelle concentrations, finite loading effects in micelles and biomembranes, the free energies and structure of liquid interfaces, microemulsions, and many more related topics, which often are of great practical importance.
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Affiliation(s)
- Andreas Klamt
- COSMOlogic GmbH & Co KG, Imbacher Weg 46, D-51379 Leverkusen, Germany.
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38
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Ebert A, Hannesschlaeger C, Goss KU, Pohl P. Passive Permeability of Planar Lipid Bilayers to Organic Anions. Biophys J 2018; 115:1931-1941. [PMID: 30360927 PMCID: PMC6303230 DOI: 10.1016/j.bpj.2018.09.025] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 09/20/2018] [Accepted: 09/26/2018] [Indexed: 11/23/2022] Open
Abstract
The membrane permeability P of organic ions was reported to be governed by the structure of the permeating molecule. Thus far, it is unclear whether the ion structure alters membrane partition or translocation proper across the membrane. Here, we obtained P values for 24 anionic compounds (18 concrete values, 6 upper limits) measuring the current that they carry through folded planar lipid bilayers. The P values range over more than 10 log units. Our measured permeability values correlate well (r = 0.95; logRMSE 0.74) with the hexadecane/water partition coefficients of the respective chemicals predicted by the COSMO-RS theory. Other attempts to predict P from the partition coefficient of the neutral molecule and from the solvation energy (Born energy) that opposes transfer into the membrane once the molecule is charged were unsuccessful. The uncertainties in assigning an effective radius to nonspherical molecules were much too large. The observation underlines that the actual structure of the molecules needs to be considered to predict partition and thus P by the solubility-diffusion model.
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Affiliation(s)
- Andrea Ebert
- Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany; Institute of Biophysics, Johannes Kepler University, Linz, Austria
| | | | - Kai-Uwe Goss
- Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany; Institute of Chemistry, Martin Luther University, Halle, Germany
| | - Peter Pohl
- Institute of Biophysics, Johannes Kepler University, Linz, Austria.
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MURAKAMI K, HORI K, MAEDA K, FUKUYAMA M, YOSHIDA Y. Adsorption and Distribution of Ions to a Bilayer Lipid Membrane. BUNSEKI KAGAKU 2018. [DOI: 10.2116/bunsekikagaku.67.581] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Koji MURAKAMI
- Department of Chemistry and Materials Technology, Kyoto Institute of Technology
| | - Kisho HORI
- Department of Chemistry and Materials Technology, Kyoto Institute of Technology
| | - Kohji MAEDA
- Department of Chemistry and Materials Technology, Kyoto Institute of Technology
| | - Mao FUKUYAMA
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
| | - Yumi YOSHIDA
- Department of Chemistry and Materials Technology, Kyoto Institute of Technology
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40
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pH-dependent surface electrostatic effects in retention on immobilized artificial membrane chromatography: Determination of the intrinsic phospholipid-water sorption coefficients of diverse analytes. J Chromatogr A 2018; 1570:172-182. [DOI: 10.1016/j.chroma.2018.07.081] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 07/24/2018] [Accepted: 07/28/2018] [Indexed: 11/18/2022]
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41
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König G, Reetz MT, Thiel W. 1-Butanol as a Solvent for Efficient Extraction of Polar Compounds from Aqueous Medium: Theoretical and Practical Aspects. J Phys Chem B 2018; 122:6975-6988. [PMID: 29897756 DOI: 10.1021/acs.jpcb.8b02877] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The extraction of polar molecules from aqueous solution is a challenging task in organic synthesis. 1-Butanol has been used sporadically as an eluent for polar molecules, but it is unclear which molecular features drive its efficiency. Here, we employ free energy simulations to study the partitioning of 15 solutes between water and 1-butanol. The simulations demonstrate that the high affinity of polar molecules to the wet 1-butanol phase is associated with its nanostructure. Small inverse micelles of water are able to accommodate polar solutes and locally mimic an aqueous environment. We verify the simulations based on partition coefficients between water and 1-octanol, and include a blind prediction of the water/1-butanol partition coefficient of cyclohexane-1,2-diol. The calculations are in excellent agreement with experiment, reaching root-mean-square deviations below 0.7 kcal/mol. Actual extractions of cyclohexane-1,2-diol from buffer solutions that mimic cell lysates and suspensions in biocatalytic reactions further exemplify our findings. The yields highlight that extractions with 1-butanol can be significantly more efficient than the conventional protocol based on ethyl acetate.
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Affiliation(s)
- Gerhard König
- Max-Planck-Institut für Kohlenforschung , 45470 Mülheim an der Ruhr , Germany.,Laboratory for Biomolecular Simulation Research, Center for Integrative Proteomics Research, and Department of Chemistry and Chemical Biology , Rutgers University , Piscataway , New Jersey 08854 , United States
| | - Manfred T Reetz
- Max-Planck-Institut für Kohlenforschung , 45470 Mülheim an der Ruhr , Germany.,Department of Chemistry , Philipps-University Marburg , 35032 Marburg , Germany
| | - Walter Thiel
- Max-Planck-Institut für Kohlenforschung , 45470 Mülheim an der Ruhr , Germany
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42
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Kitt JP, Bryce DA, Minteer SD, Harris JM. Confocal Raman Microscopy for in Situ Measurement of Phospholipid-Water Partitioning into Model Phospholipid Bilayers within Individual Chromatographic Particles. Anal Chem 2018; 90:7048-7055. [PMID: 29757613 DOI: 10.1021/acs.analchem.8b01452] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The phospholipid-water partition coefficient is a commonly measured parameter that correlates with drug efficacy, small-molecule toxicity, and accumulation of molecules in biological systems in the environment. Despite the utility of this parameter, methods for measuring phospholipid-water partition coefficients are limited. This is due to the difficulty of making quantitative measurements in vesicle membranes or supported phospholipid bilayers, both of which are small-volume phases that challenge the sensitivity of many analytical techniques. In this work, we employ in situ confocal Raman microscopy to probe the partitioning of a model membrane-active compound, 2-(4-isobutylphenyl) propionic acid or ibuprofen, into both hybrid- and supported-phospholipid bilayers deposited on the pore walls of individual chromatographic particles. The large surface-area-to-volume ratio of chromatographic silica allows interrogation of a significant lipid bilayer area within a very small volume. The local phospholipid concentration within a confocal probe volume inside the particle can be as high as 0.5 M, which overcomes the sensitivity limitations of making measurements in the limited membrane areas of single vesicles or planar supported bilayers. Quantitative determination of ibuprofen partitioning is achieved by using the phospholipid acyl-chains of the within-particle bilayer as an internal standard. This approach is tested for measurements of pH-dependent partitioning of ibuprofen into both hybrid-lipid and supported-lipid bilayers within silica particles, and the results are compared with octanol-water partitioning and with partitioning into individual optically trapped phospholipid vesicle membranes. Additionally, the impact of ibuprofen partitioning on bilayer structure is evaluated for both within-particle model membranes and compared with the structural impacts of partitioning into vesicle lipid bilayers.
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Affiliation(s)
- Jay P Kitt
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112-0850 United States
| | - David A Bryce
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112-0850 United States
| | - Shelley D Minteer
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112-0850 United States
| | - Joel M Harris
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112-0850 United States
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43
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Bittermann K, Linden L, Goss KU. Screening tools for the bioconcentration potential of monovalent organic ions in fish. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2018; 20:845-853. [PMID: 29714798 DOI: 10.1039/c8em00084k] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Currently the bioaccumulation potential of organic chemicals is assessed in a first tier approach via their octanol-water partition coefficient. This approach has been developed for neutral chemicals and cannot work for ionizable and ionic chemicals because the latter have different sorption-mechanisms and -preferences. Thus, suitable screening tools for the bioconcentration potential of ionic and ionizable chemicals need to be developed because it cannot be expected that these chemicals are non-bioaccumulative per se. Here, we present such screening tools for monovalent ions and ionizable chemicals based on calibrated sorption models for membrane lipids, structural proteins and albumin. The molecular descriptors used for these models arise from quantum chemical calculations and are based on COSMO-RS theory. When we applied our screening tools to 1839 preselected chemicals from the REACH registration data base, we identified 187 chemicals as potentially bioconcentrating (still ignoring any kind of metabolism). Among these were carbon and sulphur based aromatic and aliphatic acids mostly with a rather high molecular surface area. We hope that this outcome will trigger further research on ion specific sorption mechanisms and lead to a re-evaluation of the bioconcentration potential of ionic chemicals.
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Affiliation(s)
- Kai Bittermann
- Helmholtz Centre for Environmental Research UFZ, Department of Analytical Environmental Chemistry, Permoserstr. 15, D-04318 Leipzig, Germany.
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44
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Goss KU, Bittermann K, Henneberger L, Linden L. Equilibrium biopartitioning of organic anions - A case study for humans and fish. CHEMOSPHERE 2018; 199:174-181. [PMID: 29438944 DOI: 10.1016/j.chemosphere.2018.02.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 01/31/2018] [Accepted: 02/04/2018] [Indexed: 05/21/2023]
Abstract
In this work we combine partition coefficients between water and membrane lipid, storage lipid, the plasma protein albumin as well as structural protein with the tissue dependent fraction of the respective phases in order to obtain a clearer picture on the relevance of various biological tissues for the bioaccumulation of 31 organic anions. Most of the partition coefficients are based on experimental data, supplemented by some predicted ones. The data suggest that the plasma protein, albumin, will be the major sorption matrix in mammals. Only small fractions of the studied chemicals will occur freely dissolved in an organism. For the investigated acids with pKa <5, partitioning is dominated by the ionic species rather than the corresponding neutral species. Bioconcentration in fish is not expected to occur for many of these acids unless pH in the aqueous environment is low or specific sorption mechanisms are relevant. In contrast, biomagnification in terrestrial mammals would be expected for most organic anions if they are not sufficiently metabolized. We conclude that sorption is important for the toxicokinetics of ionizable organic chemicals and the dominating sorbing matrices are quite different from those for neutral species.
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Affiliation(s)
- Kai-Uwe Goss
- Helmholtz Centre for Environmental Research UFZ, Department of Analytical Environmental Chemistry, Permoserstr. 15, D-04318 Leipzig, Germany; University of Halle-Wittenberg, Institute of Chemistry, Kurt-Mothes-Str. 2, D-06120 Halle, Germany.
| | - Kai Bittermann
- Helmholtz Centre for Environmental Research UFZ, Department of Analytical Environmental Chemistry, Permoserstr. 15, D-04318 Leipzig, Germany
| | - Luise Henneberger
- Helmholtz Centre for Environmental Research UFZ, Department of Cell Toxicology, Permoserstr. 15, D-04318 Leipzig, Germany
| | - Lukas Linden
- Helmholtz Centre for Environmental Research UFZ, Department of Analytical Environmental Chemistry, Permoserstr. 15, D-04318 Leipzig, Germany
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45
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Loureiro DRP, Soares JX, Lopes D, Macedo T, Yordanova D, Jakobtorweihen S, Nunes C, Reis S, Pinto MMM, Afonso CMM. Accessing lipophilicity of drugs with biomimetic models: A comparative study using liposomes and micelles. Eur J Pharm Sci 2018; 115:369-380. [PMID: 29366962 DOI: 10.1016/j.ejps.2018.01.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 01/12/2018] [Accepted: 01/13/2018] [Indexed: 12/24/2022]
Abstract
Lipophilicity is a physicochemical property of crucial importance in drug discovery and drug design. Biomimetic models, such as liposomes and micelles, constitute a valuable tool for the assessment of lipophilicity through the determination of partition coefficients (log Kp). However, the lack of standardization hampers the judgment about which model or method has the best and broadest passive drug permeation predictive capacity. This work provides a comparative analysis between the methodologies based on biomimetic models to determine the partition coefficient (log Kp). For that purpose, a set of reference substances preconized by the Organization for Economic Cooperation and Development (OECD) guidelines was used. The biomimetic models employed were liposomes and micelles composed by 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC) and hexadecylphosphocholine (HePC), respectively. Both lipids were used as representative phospholipids of natural membranes. The partition coefficients between biomimetic models and aqueous phases were determined by derivative spectroscopy at physiological conditions (37 °C and pH 7.4). The partition coefficients obtained using biomimetic models are quite different and more reliable than the ones obtained using an octanol/water system. Comparing the performance of the two biomimetic models, micelles revealed to be suitable only for substances with high molar absorption coefficient and log Kp > 3, but in general liposomes are the best model for accessing lipophilicity of drugs. Furthermore, a comparison between experimental data and the partition coefficients determined by the computational method COSMOmic is also provided and discussed. As a final summarizing result, a decision tree is provided in order to guide the selection of a tool for assessing the lipophilicity of drugs.
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Affiliation(s)
- Daniela R P Loureiro
- Department of Chemical Sciences, Laboratory of Organic and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
| | - José X Soares
- LAQV-REQUIMTE, Department of Chemical Sciences, Laboratory of Applied Chemistry, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
| | - Daniela Lopes
- LAQV-REQUIMTE, Department of Chemical Sciences, Laboratory of Applied Chemistry, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
| | - Tiago Macedo
- Department of Chemical Sciences, Laboratory of Organic and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
| | - Denitsa Yordanova
- Institute of Thermal Separation Processes, Hamburg University of Technology, Germany
| | - Sven Jakobtorweihen
- Institute of Thermal Separation Processes, Hamburg University of Technology, Germany
| | - Cláudia Nunes
- LAQV-REQUIMTE, Department of Chemical Sciences, Laboratory of Applied Chemistry, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
| | - Salette Reis
- LAQV-REQUIMTE, Department of Chemical Sciences, Laboratory of Applied Chemistry, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
| | - Madalena M M Pinto
- Department of Chemical Sciences, Laboratory of Organic and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal; Interdisciplinary Center of Marine and Environmental Investigation (CIIMAR/CIMAR), Edifício do Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4050-208 Matosinhos, Porto, Portugal
| | - Carlos M M Afonso
- Department of Chemical Sciences, Laboratory of Organic and Pharmaceutical Chemistry, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal; Interdisciplinary Center of Marine and Environmental Investigation (CIIMAR/CIMAR), Edifício do Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4050-208 Matosinhos, Porto, Portugal.
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46
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Golius A, Gorb L, Isayev O, Leszczynski J. Diffusion of energetic compounds through biological membrane: Application of classical MD and COSMOmic approximations. J Biomol Struct Dyn 2018; 37:247-255. [PMID: 29301457 DOI: 10.1080/07391102.2018.1424037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Computational studies of the potential biological impact of several energetic compounds were performed. The most commonly used explosives were considered in the present studies: trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), 2,4-dinitroanisole (DNAN), and 5-Nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO). The effect of such factors as ionic strength and presence of DMSO in the water solution on the structure of the membrane were considered using the POPC lipid bilayer as an example. Molecular dynamics (MD) simulations revealed that, even on a short-time scale, the influence of those additives is noticeable, and therefore those factors should always be taken into account. The MD and the COSMOmic approaches were used to elucidate the ability of the energetic compounds to penetrate the living cell. Calculated free energy profiles and partitioning coefficients revealed distributions of the compounds in the lipid bilayer as well as an overall ability to enter the cell. MD in this case provides a better representation of the free energy profile, while the COSMOmic approach works better to predict log(Klipw) values. The effect of the functional group was observed for the profiles that were obtained using the MD method.
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Affiliation(s)
- Anastasiia Golius
- a Department of Chemistry, Physics and Atmospheric Science , Jackson State University , Jackson , Mississippi , USA
| | - Leonid Gorb
- b Institute of Molecular Biology and Genetics , Kyiv , Ukraine
| | - Olexander Isayev
- c Division of Chemical Biology and Medicinal Chemistry , Eshelman School of Pharmacy, University of North Carolina at Chapel Hill , North Carolina , USA
| | - Jerzy Leszczynski
- a Department of Chemistry, Physics and Atmospheric Science , Jackson State University , Jackson , Mississippi , USA
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47
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Bittermann K, Goss KU. Predicting apparent passive permeability of Caco-2 and MDCK cell-monolayers: A mechanistic model. PLoS One 2017; 12:e0190319. [PMID: 29281711 PMCID: PMC5744993 DOI: 10.1371/journal.pone.0190319] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 12/12/2017] [Indexed: 01/16/2023] Open
Abstract
Experimentally derived apparent permeabilities, Papp, through cell monolayers such as Caco-2 and MDCK are considered to be an in-vitro gold standard for assessing the uptake efficiency of drugs. Here, we present a mechanistic model that describes 'passive' Papp values (i.e., neglecting active transport) by accounting for the different resistances solutes encounter when permeating a cell monolayer. We described three parallel permeation pathways, namely a cytosolic-, paracellular-, and lateral route, each of which consists of a number of serial resistances. These resistances were accounted for via a mechanistic depiction of the underlying processes that are largely based on literature work. For the present Papp dataset, about as much chemicals are dominated by the cytosolic route as were dominated by the paracellular route, while the lateral route was negligible. For the cytosolic route by far the most chemicals found their main resistance in the various water layers and not in the membrane. Although correlations within the subclasses of chemicals dominated by a specific permeation route were rather poor, we could overall satisfyingly predict Papp for 151 chemicals at a pH of 7.4 (R2 = 0.77, RMSE = 0.48). For a specific evaluation of the intrinsic membrane permeability, Pm, a second experimental dataset based on experiments with black lipid membranes, BLM, was evaluated. Pm could be predicted for 37 chemicals with R2 = 0.91 and RMSE = 0.64 log units.
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Affiliation(s)
- Kai Bittermann
- Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Kai-Uwe Goss
- Analytical Environmental Chemistry, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
- Department of Chemistry, University of Halle-Wittenberg, Halle, Germany
- * E-mail:
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48
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Tanoue R, Margiotta-Casaluci L, Huerta B, Runnalls TJ, Nomiyama K, Kunisue T, Tanabe S, Sumpter JP. Uptake and Metabolism of Human Pharmaceuticals by Fish: A Case Study with the Opioid Analgesic Tramadol. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:12825-12835. [PMID: 28977743 DOI: 10.1021/acs.est.7b03441] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Recent species-extrapolation approaches to the prediction of the potential effects of pharmaceuticals present in the environment on wild fish are based on the assumption that pharmacokinetics and metabolism in humans and fish are comparable. To test this hypothesis, we exposed fathead minnows to the opiate pro-drug tramadol and examined uptake from the water into the blood and brain and the metabolism of the drug into its main metabolites. We found that plasma concentrations could be predicted reasonably accurately based on the lipophilicity of the drug once the pH of the water was taken into account. The concentrations of the drug and its main metabolites were higher in the brain than in the plasma, and the observed brain and plasma concentration ratios were within the range of values reported in mammalian species. This fish species was able to metabolize the pro-drug tramadol into the highly active metabolite O-desmethyl tramadol and the inactive metabolite N-desmethyl tramadol in a similar manner to that of mammals. However, we found that concentration ratios of O-desmethyl tramadol to tramadol were lower in the fish than values in most humans administered the drug. Our pharmacokinetic data of tramadol in fish help bridge the gap between widely available mammalian pharmacological data and potential effects on aquatic organisms and highlight the importance of understanding drug uptake and metabolism in fish to enable the full implementation of predictive toxicology approaches.
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Affiliation(s)
- Rumi Tanoue
- Centre for Marine Environmental Studies, Ehime University , 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
- Institute of Environment, Health and Societies, Brunel University , Uxbridge, Middlesex, London UB8 3PH, United Kingdom
| | - Luigi Margiotta-Casaluci
- Institute of Environment, Health and Societies, Brunel University , Uxbridge, Middlesex, London UB8 3PH, United Kingdom
| | - Belinda Huerta
- Institute of Environment, Health and Societies, Brunel University , Uxbridge, Middlesex, London UB8 3PH, United Kingdom
| | - Tamsin J Runnalls
- Institute of Environment, Health and Societies, Brunel University , Uxbridge, Middlesex, London UB8 3PH, United Kingdom
| | - Kei Nomiyama
- Centre for Marine Environmental Studies, Ehime University , 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Tatsuya Kunisue
- Centre for Marine Environmental Studies, Ehime University , 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Shinsuke Tanabe
- Centre for Marine Environmental Studies, Ehime University , 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - John P Sumpter
- Institute of Environment, Health and Societies, Brunel University , Uxbridge, Middlesex, London UB8 3PH, United Kingdom
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49
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Yordanova D, Ritter E, Smirnova I, Jakobtorweihen S. Micellization and Partition Equilibria in Mixed Nonionic/Ionic Micellar Systems: Predictions with Molecular Models. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:12306-12316. [PMID: 28967760 DOI: 10.1021/acs.langmuir.7b02813] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In practical applications, surfactant solutions are mostly used in mixtures of nonionic and ionic surfactants because they have improved characteristics compared to those of single surfactant solutions. By adjusting the composition of the micelles and the pH value, the solubilization of solutes can be enhanced. Nevertheless, the partitioning of solutes between nonionic/ionic mixed micelles and the aqueous phase is studied to a much lesser extent than for single surfactant solutions. Theoretical methods to predict partition equilibria in mixed micelles are of interest for screening studies. For those, the composition of the mixed micelle has to be known. Here we investigate mixtures of TX-114 (Triton X-114), Brij35 (C12E23), SDS (sodium dodecyl sulfate), and CTAB (cetyltrimethylammonium bromide). First, to investigate the surfactant compositions in the micelles, molecular dynamics (MD) self-assembly simulations were applied. Thereafter, the predictive COSMO-RS model, which applies the pseudophase approach, and its extension to anisotropic systems termed COSMOmic were compared for the prediction of partition equilibria in mixed micelles, where various molar ratios of the surfactants were considered. It could be demonstrated that both methods are applicable and lead to reasonable predictions for neutral molecules. However, taking into account the three-dimensional structure of the micelle is beneficial because the calculations with COSMOmic are in better agreement with experimental results. Because the partitioning behavior of ionizable molecules in mixed micelles is of particular interest, the partitioning of ionized isovanillin in mixed Brij35/CTAB micelles at different micelle compositions was calculated with COSMOmic. Using a thermodynamic cycle, the position-dependent pKa of isovanillin within the micelle is calculated on the basis of COSMOmic free energy profiles. As a result, the protolytic equilibrium of isovanillin within the micelles can be taken into account, which is crucial for the reliable prediction of partition coefficients.
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Affiliation(s)
- D Yordanova
- Hamburg University of Technology , Institute of Thermal Separation Processes, Eissendorfer Str. 38, 21073 Hamburg, Germany
| | - E Ritter
- Hamburg University of Technology , Institute of Thermal Separation Processes, Eissendorfer Str. 38, 21073 Hamburg, Germany
| | - I Smirnova
- Hamburg University of Technology , Institute of Thermal Separation Processes, Eissendorfer Str. 38, 21073 Hamburg, Germany
| | - S Jakobtorweihen
- Hamburg University of Technology , Institute of Thermal Separation Processes, Eissendorfer Str. 38, 21073 Hamburg, Germany
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Klamt A. The
COSMO
and
COSMO‐RS
solvation models. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2017. [DOI: 10.1002/wcms.1338] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Andreas Klamt
- COSMOlogic GmbH&CoKG Leverkusen Germany
- Institute of Physical and Theoretical ChemistryUniversity of Regensburg Regensburg Germany
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