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Giménez-Bañón MJ, Paladines-Quezada DF, Moreno-Olivares JD, Bleda-Sánchez JA, Fernández-Fernández JI, Parra-Torrejón B, Ramírez-Rodríguez GB, Delgado-López JM, Gil-Muñoz R. Methyl Jasmonate and Nanoparticles Doped with Methyl Jasmonate affect the Cell Wall Composition of Monastrell Grape Skins. Molecules 2023; 28:molecules28031478. [PMID: 36771144 PMCID: PMC9921610 DOI: 10.3390/molecules28031478] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 01/23/2023] [Accepted: 01/29/2023] [Indexed: 02/05/2023] Open
Abstract
The structural composition of the cell wall of grape skins is related to the cell wall integrity and subsequent extraction of the different compounds that are contained inside vacuoles and also the cell wall breakdown products. Different reports have established that methyl jasmonate (MeJ) produces changes in the composition of the grape skin cell wall. The use of elicitors to promote the production of secondary metabolites in grapes has been studied in several reports; however, its study linked to nanotechnology is less developed. These facts led us to study the effect of methyl jasmonate (MeJ) and nanoparticles doped with MeJ (nano-MeJ) on the cell walls of Monastrell grapes during three seasons. Both treatments tended to increase cell wall material (CWM) and caused changes in different components of the skin cell walls. In 2019 and 2021, proteins were enlarged in both MeJ and nano-MeJ-treated grapes. A general decrease in total phenolic compounds was detected with both treatments, in addition to an increment in uronic acids when the grapes were well ripened. MeJ and nano-MeJ produced a diminution in the amount of cellulose in contrast to an increase in hemicellulose. It should be noted that the effects with nano-MeJ treatment occurred at a dose 10 times lower than with MeJ treatment.
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Nelson C, Schmidt AB, Adelabu I, Nantogma S, Kiselev VG, Abdurraheem A, de Maissin H, Lehmkuhl S, Appelt S, Theis T, Chekmenev EY. Parahydrogen-Induced Carbon-13 Radiofrequency Amplification by Stimulated Emission of Radiation. Angew Chem Int Ed Engl 2023; 62:e202215678. [PMID: 36437237 PMCID: PMC9889133 DOI: 10.1002/anie.202215678] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 11/29/2022]
Abstract
The feasibility of Carbon-13 Radiofrequency (RF) Amplification by Stimulated Emission of Radiation (C-13 RASER) is demonstrated on a bolus of liquid hyperpolarized ethyl [1-13 C]acetate. Hyperpolarized ethyl [1-13 C]acetate was prepared via pairwise addition of parahydrogen to vinyl [1-13 C]acetate and polarization transfer from nascent parahydrogen-derived protons to the carbon-13 nucleus via magnetic field cycling yielding C-13 nuclear spin polarization of approximately 6 %. RASER signals were detected from samples with concentration ranging from 0.12 to 1 M concentration using a non-cryogenic 1.4T NMR spectrometer equipped with a radio-frequency detection coil with a quality factor (Q) of 32 without any modifications. C-13 RASER signals were observed for several minutes on a single bolus of hyperpolarized substrate to achieve 21 mHz NMR linewidths. The feasibility of creating long-lasting C-13 RASER on biomolecular carriers opens a wide range of new opportunities for the rapidly expanding field of C-13 magnetic resonance hyperpolarization.
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78
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Canchola A, Langmo S, Meletz R, Lum M, Lin YH. External Factors Modulating Vaping-Induced Thermal Degradation of Vitamin E Acetate. Chem Res Toxicol 2023; 36:83-93. [PMID: 36534744 PMCID: PMC9846828 DOI: 10.1021/acs.chemrestox.2c00298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Indexed: 12/23/2022]
Abstract
Despite previous studies indicating the thermal stability of vitamin E acetate (VEA) at low temperatures, VEA has been shown to readily decompose into various degradation products such as alkenes, long-chain alcohols, and carbonyls such as duroquinone (DQ) at vaping temperatures of <200 °C. While most models simulate the thermal decomposition of e-liquids under pyrolysis conditions, numerous factors, including vaping behavior, device construction, and the surrounding environment, may impact the thermal degradation process. In this study, we investigated the role of the presence of molecular oxygen (O2) and transition metals in promoting thermal oxidation of e-liquids, resulting in greater degradation than predicted by pure pyrolysis. Thermal degradation of VEA was performed in inert (N2) and oxidizing atmospheres (clean air) in the absence and presence of Ni-Cr and Cu-Ni alloy nanopowders, metals commonly found in the heating coil and body of e-cigarettes. VEA degradation was analyzed using thermogravimetric analysis (TGA) and gas chromatography/mass spectrometry (GC/MS). While the presence of O2 was found to significantly enhance the degradation of VEA at both high (356 °C) and low (176 °C) temperatures, the addition of Cu-Ni to oxidizing atmospheres was found to greatly enhance VEA degradation, resulting in the formation of numerous degradation products previously identified in VEA vaping emissions. O2 and Cu-Ni nanopowder together were also found to significantly increase the production of OH radicals, which has implications for e-liquid degradation pathways as well as the potential risk of oxidative damage to biological systems in real-world vaping scenarios. Ultimately, the results presented in this study highlight the importance of oxidation pathways in VEA thermal degradation and may aid in the prediction of thermal degradation products from e-liquids.
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79
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Wu Y, Li W, Wang L, Wu Y, Wang Y, Wang Y, Meng H. Enhancing the selective synthesis of butyrate in microbial electrosynthesis system by gas diffusion membrane composite biocathode. CHEMOSPHERE 2022; 308:136088. [PMID: 36029854 DOI: 10.1016/j.chemosphere.2022.136088] [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: 06/05/2022] [Revised: 08/09/2022] [Accepted: 08/14/2022] [Indexed: 06/15/2023]
Abstract
The reduction of carbon dioxide (CO2) to high value-added multi-carbon compounds at the cathode is an emerging application of microbial electrosynthesis system (MES). In this study, a composite cathode consisting of hollow fiber membrane (HFM) and the carbon felt is designed to enhance the CO2 mass transfer of the cathode. The result shows that the main products are acetate and butyrate without other substances. The electrochemical performance of the electrode is significantly improved after biofilm becomes matures. The composite cathode significantly reduces the "threshold" for the synthesis of butyrate. Moreover, CO2 is dissolved and protons are consumed by synthesizing volatile fatty acids (VFAs) to maintain a stable pH inside the composite electrode. The synthesis mechanism of butyrate is that CO2 is converted sequentially into acetate and butyrate. The microenvironment of the composite electrode enriches Firmicute. This composite electrode provides a novel strategy for regulating the microenvironment.
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Gao Y, Li Z, Cai J, Zhang L, Liang Q, Jiang Y, Zeng RJ. Metal nanoparticles increased the lag period and shaped the microbial community in slurry-electrode microbial electrosynthesis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 838:156008. [PMID: 35588810 DOI: 10.1016/j.scitotenv.2022.156008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 05/12/2022] [Accepted: 05/12/2022] [Indexed: 06/15/2023]
Abstract
Concerns about energy crisis and CO2 emission have motivated the development of microbial electrosynthesis (MES); recent studies have showed the potential of novel slurry-electrode MES. In this study, the effect of nonprecious metal nanoparticles (NPs) on the performance of slurry-electrode MES was systematically evaluated in terms of chemical production, physicochemical properties, electrochemical characterization, and microbial community. Ni and Cu NPs increased the lag period from 6 to 15 days for acetate production, while Mo NPs showed no apparent effect. However, these metal NPs slightly affected the final total acetate production (ca. 10 g L-1), Faradic efficiency (ca. 50%), net water flux across the anion exchange membrane (ca. 6 mL d-1), or electrochemical characterization of catholyte. BRH-c20a was enriched as the dominated microbe (>48%), and its relative abundance was largely affected by the addition of metal NPs. This study demonstrates that metal NPs affect the performance of biocathodes, mainly by shaping the microbial community.
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81
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Zhou M, Zeng C, Liu G, Luo H, Zhang R. Enhanced CO 2 reduction and acetate synthesis in autotrophic biocathode by N-Hexanoyl-L-homoserine lactone (C6HSL)-based quorum-sensing regulation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 836:155724. [PMID: 35523344 DOI: 10.1016/j.scitotenv.2022.155724] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/12/2022] [Accepted: 05/01/2022] [Indexed: 06/14/2023]
Abstract
The aim of this study was to investigate the ecological role of quorum-sensing signaling molecule on the autotrophic biocathode for CO2 reduction and acetate synthesis. As a typical quorum-sensing signaling molecule, N-Hexanoyl-L-homoserine lactone (C6HSL) was used to regulate the construction of cathode biofilm. Results showed that the maximum acetate production from CO2 reduction improved by 94.8%, and the maximum Faraday efficiency of the microbial electrosynthesis system enhanced by 71.7%, with the regulation of C6HSL. Electrochemical analyses indicated that higher electrochemical activity and lower charge resistance of biocathode were obtained with C6HSL than without C6HSL. Confocal laser scanning microscopy and electron inhibitor experiment suggested that exogenous C6HSL increased living biomass in the biofilm and facilitated the electron transfer pathway related to NADH dehydrogenase-CoQ and proton motive force. With the C6HSL regulation, the relative abundance of hydrogen producers (e.g., Desulfovibrio and Desulfomicrobium) increased, contributing to the improved performance of autotrophic biocathode.
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Matsumoto S, Traber MG, Leonard SW, Choi J, Fang X, Maishan M, Wick KD, Jones KD, Calfee CS, Gotts JE, Matthay MA. Aerosolized vitamin E acetate causes oxidative injury in mice and in alveolar macrophages. Am J Physiol Lung Cell Mol Physiol 2022; 322:L771-L783. [PMID: 35318859 PMCID: PMC9109788 DOI: 10.1152/ajplung.00482.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 03/07/2022] [Accepted: 03/17/2022] [Indexed: 12/14/2022] Open
Abstract
Although vitamin E acetate (VEA) is suspected to play a causal role in the development of electronic-cigarette, or vaping, product use-associated lung injury (EVALI), the underlying biological mechanisms of pulmonary injury are yet to be determined. In addition, no study has replicated the systemic inflammation observed in humans in a murine EVALI model, nor investigated potential additive toxicity of viral infection in the setting of exposure to vaping products. To identify the mechanisms driving VEA-related lung injury and test the hypothesis that viral infection causes additive lung injury in the presence of aerosolized VEA, we exposed mice to aerosolized VEA for extended times, followed by influenza infection in some experiments. We used mass spectrometry to evaluate the composition of aerosolized VEA condensate and the VEA deposition in murine or human alveolar macrophages. Extended vaping for 28 days versus 15 days did not worsen lung injury but caused systemic inflammation in the murine EVALI model. Vaping plus influenza increased lung water compared with virus alone. Murine alveolar macrophages exposed to vaped VEA hydrolyzed the VEA to vitamin E with evidence of oxidative stress in the alveolar space and systemic circulation. Aerosolized VEA also induced cell death and chemokine release and reduced efferocytotic function in human alveolar macrophages in vitro. These findings provide new insights into the biological mechanisms of VEA toxicity.
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Canchola A, Meletz R, Khandakar RA, Woods M, Lin YH. Temperature dependence of emission product distribution from vaping of vitamin E acetate. PLoS One 2022; 17:e0265365. [PMID: 35324938 PMCID: PMC8947410 DOI: 10.1371/journal.pone.0265365] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 02/26/2022] [Indexed: 01/01/2023] Open
Abstract
Nearly two years after vitamin E acetate (VEA) was identified as the potential cause of the 2019–2020 outbreak of e-cigarette, or vaping product-associated lung injuries (EVALI), the toxicity mechanisms of VEA vaping are still yet to be fully understood. Studies since the outbreak have found that e-liquids such as VEA undergo thermal degradation during the vaping process to produce various degradation products, which may pose a greater risk of toxicity than exposure to unvaped VEA. Additionally, a wide range of customizable parameters–including the model of e-cigarette used, puffing topography, or the applied power/temperature used to generate aerosols–have been found to influence the physical properties and chemical compositions of vaping emissions. However, the impact of heating coil temperature on the chemical composition of VEA vaping emissions has not been fully assessed. In this study, we investigated the emission product distribution of VEA vaping emissions produced at temperatures ranging from 176 to 356°C, corresponding to a variable voltage vape pen set at 3.3 to 4.8V. VEA degradation was found to be greatly enhanced with increasing temperature, resulting in a shift towards the production of lower molecular weight compounds, such as the redox active duroquinone (DQ) and short-chain alkenes. Low temperature vaping of VEA resulted in the production of long-chain molecules, such as phytol, exposure to which has been suggested to induce lung damage in previous studies. Furthermore, differential product distribution was observed in VEA degradation products generated from vaping and from pyrolysis using a tube furnace in the absence of the heating coil at equivalent temperatures, suggesting the presence of external factors such as metals or oxidation that may enhance VEA degradation during vaping. Overall, our findings indicate that vaping behavior may significantly impact the risk of exposure to toxic vaping products and potential for vaping-related health concerns.
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Liu Z, Zhang Z, Peng J, Wu J, Huo Y. Rapid removal of trace haloacetic acids from drinking water by a continuous adsorption process using graphene oxide. ENVIRONMENTAL TECHNOLOGY 2022; 43:1544-1550. [PMID: 33089761 DOI: 10.1080/09593330.2020.1841307] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/16/2020] [Indexed: 06/11/2023]
Abstract
Significant health risks are caused by trace levels of haloacetic acids (HAAs) in drinking water. We used graphene oxide (GO), a high-performance absorbent, to remove monochloroacetic acid (MCAA), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA). 31.6%, 27.1% and 30.2% of MCAA, DCAA and TCAA in drinking water could be rapidly removed within 2 min by the interaction of intermolecular hydrogen bonds between GO and HAAs. On the other hand, as a type of weak interaction, intermolecular hydrogen bonds are easy to fracture, which leads to the recovery of GO. The removal efficiency of MCAA, DCAA and TCAA monotonously decreased with increasing pH from 3 to 11. Temperature was not an important influence on the removal efficiency of HAAs, and only affected the interaction of intermolecular hydrogen bonds between GO and HAAs. A continuous adsorption process was used for further improving the removal efficiency of HAAs, and the concentration of total HAAs decreased from 436 to 52.5 μg L-1 after five adsorption processes. The total contact time was just 2.25 min, which was faster than other reported adsorbents, and total HAAs could be decreased by 88%. The innovative process in this study provides an effective method for application of GO to rapidly remove HAAs in drinking water.
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85
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Sulaiman S, Ahmad S, Naz SS, Qaisar S, Muhammad S, Alotaibi A, Ullah R. Synthesis of Copper Oxide-Based Nanoformulations of Etoricoxib and Montelukast and Their Evaluation through Analgesic, Anti-Inflammatory, Anti-Pyretic, and Acute Toxicity Activities. Molecules 2022; 27:1433. [PMID: 35209221 PMCID: PMC8875186 DOI: 10.3390/molecules27041433] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 02/13/2022] [Accepted: 02/14/2022] [Indexed: 02/06/2023] Open
Abstract
Copper oxide nanoparticles (CuO NPs) were synthesized through the coprecipitation method and used as nanocarriers for etoricoxib (selective COX-2 inhibitor drug) and montelukast (leukotriene product inhibitor drug) in combination therapy. The CuO NPs, free drugs, and nanoformulations were investigated through UV/Vis spectroscopy, FTIR spectroscopy, XRD, SEM, and DLS. SEM imaging showed agglomerated nanorods of CuO NPs of about 87 nm size. The CE1, CE2, and CE6 nanoformulations were investigated through DLS, and their particle sizes were 271, 258, and 254 nm, respectively. The nanoformulations were evaluated through in vitro anti-inflammatory activity, in vivo anti-inflammatory activity, in vivo analgesic activity, in vivo anti-pyretic activity, and in vivo acute toxicity activity. In vivo activities were performed on albino mice. BSA denaturation was highly inhibited by CE1, CE2, and CE6 as compared to other nanoformulations in the in vitro anti-inflammatory activity. The in vivo bioactivities showed that low doses (5 mg/kg) of nanoformulations were more potent than high doses (10 and 20 mg/kg) of free drugs in the inhibition of pain, fever, and inflammation. Lastly, CE2 was more potent than that of other nanoformulations.
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Zhou Z, Cai Z, Zhang C, Yang B, Chen L, He Y, Zhang L, Li Z. Design, synthesis, and biological evaluation of novel dual FFA1 and PPARδ agonists possessing phenoxyacetic acid scaffold. Bioorg Med Chem 2022; 56:116615. [PMID: 35051813 DOI: 10.1016/j.bmc.2022.116615] [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: 10/14/2021] [Revised: 12/24/2021] [Accepted: 01/06/2022] [Indexed: 11/11/2022]
Abstract
The free fatty acid receptor 1 (FFA1/GPR40) and peroxisome proliferator-activated receptor δ (PPARδ) have been widely considered as promising targets for type 2 diabetes mellitus (T2DM) due to their respective roles in promoting insulin secretion and improving insulin sensitivity. Hence, the dual FFA1/PPARδ agonists may exert synergistic effects by simultaneously activating FFA1 and PPARδ. The present study performed systematic exploration around previously reported FFA1 agonist 2-(2-fluoro-4-((2'-methyl-4'-(3-(methylsulfonyl)propoxy)-[1,1'-biphenyl]-3-yl)methoxy)phenoxy)acetic acid (lead compound), leading to the identification of a novel dual FFA1/PPARδ agonist 2-(2-fluoro-4-((3-(6-methoxynaphthalen-2-yl)benzyl)oxy)phenoxy)acetic acid (the optimal compound), which displayed high selectivity over PPARα and PPARγ. In addition, the docking study provided us with detailed binding modes of the optimal compound in FFA1 and PPARδ. Furthermore, the optimal compound exhibited greater glucose-lowering effects than lead compound, which might attribute to its synergistic effects by simultaneously modulating insulin secretion and resistance. Moreover, the optimal compound has an acceptable safety profile in the acute toxicity study at a high dose of 500 mg/kg Therefore, our results provided a novel dual FFA1/PPARδ agonist with excellent glucose-lowering effects in vivo.
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87
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Oza HH, Holmes EB, Bailey ES, Coleman CK, Sobsey MD. Microbial reductions and physical characterization of chitosan flocs when using chitosan acetate as a cloth filter aid in water treatment. PLoS One 2022; 17:e0262341. [PMID: 35061779 PMCID: PMC8782320 DOI: 10.1371/journal.pone.0262341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 12/22/2021] [Indexed: 11/19/2022] Open
Abstract
The World Health Organization (WHO) estimates 2.1 billion people lack access to safely managed water. Cloth filtration is often employed in rural and developing communities of South Asia for point-of-use water treatment, but bacteria and viruses are too small for efficient removal by this filtration method. Chitosan is a biodegradable, cationic, organic polymer derived from the chemical treatment of chitin that acts as a coagulant and flocculant of contaminant of microbes and other particles in water, thereby facilitating filtration of microbes. This research 1) evaluated the use of chitosan acetate as a pre-treatment coagulation-flocculation process followed by cloth filtration for microbial reductions and 2) assessed floc particle size under three stirring conditions. E. coli KO11 bacteria and MS2 coliphage virus removals were quantified using culture-based methods. Chitosan acetate coagulation-flocculation pre-treatment of water, followed by cloth filtration, met or exceeded the protective (2-star) WHO performance levels for bacteria (2 log10 reduction) and viruses (3 log10 reduction), and filtrate turbidity was consistently reduced to < 1 NTU, meeting United States Environmental Protection Agency (EPA) and WHO targets.
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88
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Migliari S, Sammartano A, Boss M, Gotthardt M, Scarlattei M, Baldari G, Silva C, Bonadonna RC, Ruffini L. Development and Validation of an Analytical HPLC Method to Assess Chemical and Radiochemical Purity of [ 68Ga]Ga-NODAGA-Exendin-4 Produced by a Fully Automated Method. Molecules 2022; 27:543. [PMID: 35056858 PMCID: PMC8778103 DOI: 10.3390/molecules27020543] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/03/2022] [Accepted: 01/12/2022] [Indexed: 11/19/2022] Open
Abstract
Background: Glucagon-like peptide 1 receptor (GLP-1R) is preferentially expressed in pancreatic islets, especially in β-cells, and highly expressed in human insulinomas and gastrinomas. In recent years several GLP-1R-avid radioligands have been developed to image insulin-secreting tumors or to provide a tentative quantitative in vivo biomarker of pancreatic β-cell mass. Exendin-4, a 39-amino acid peptide with high binding affinity to GLP-1R, has been labeled with Ga-68 for imaging with positron emission tomography (PET). Preparation conditions may influence the quality and in vivo behavior of tracers. Starting from a published synthesis and quality controls (QCs) procedure, we have developed and validated a new rapid and simple UV-Radio-HPLC method to test the chemical and radiochemical purity of [68Ga]Ga-NODAGA-exendin-4, to be used in the clinical routine. Methods: Ga-68 was obtained from a 68Ge/68Ga Generator (GalliaPharma®) and purified using a cationic-exchange cartridge on an automated synthesis module (Scintomics GRP®). NODAGA-exendin-4 contained in the reactor (10 µg) was reconstituted with HEPES and ascorbic acid. The reaction mixture was incubated at 100 °C. The product was purified through HLB cartridge, diluted, and sterilized. To validate the proposed UV-Radio-HPLC method, a stepwise approach was used, as defined in the guidance document released by the International Conference on Harmonization of Technical Requirements of Pharmaceuticals for Human Use (ICH), adopted by the European Medicines Agency (CMP/ICH/381/95 2014). The assessed parameters are specificity, linearity, precision (repeatability), accuracy, and limit of quantification. Therefore, a range of concentrations of Ga-NODAGA-exendin-4, NODAGA-exendin-4 (5, 4, 3.125, 1.25, 1, and 0.75 μg/mL) and [68Ga]Ga-NODAGA-exendin-4 were analyzed. To validate the entire production process, three consecutive batches of [68Ga]Ga-NODAGA-exendin-4 were tested. Results: Excellent linearity was found between 5-0.75 μg/mL for both the analytes (NODAGA-exendin-4 and 68Ga-NODAGA-exendin-4), with a correlation coefficient (R2) for calibration curves equal to 0.999, average coefficients of variation (CV%) < 2% (0.45% and 0.39%) and average per cent deviation value of bias from 100%, of 0.06% and 0.04%, respectively. The calibration curve for the determination of [68Ga]Ga-NODAGA-exendin-4 was linear with a R2 of 0.993 and CV% < 2% (1.97%), in accordance to acceptance criteria. The intra-day and inter-day precision of our method was statistically confirmed using 10 μg of peptide. The mean radiochemical yield was 45 ± 2.4% in all the three validation batches of [68Ga]Ga-NODAGA-exendin-4. The radiochemical purity of [68Ga]Ga-NODAGA-exendin-4 was >95% (97.05%, 95.75% and 96.15%) in all the three batches. Conclusions: The developed UV-Radio-HPLC method to assess the radiochemical and chemical purity of [68Ga]Ga-NODAGA-exendin-4 is rapid, accurate and reproducible like its fully automated production. It allows the routine use of this PET tracer as a diagnostic tool for PET imaging of GLP-1R expression in vivo, ensuring patient safety.
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Jung WO, Yoo M, Migliozzi MM, Zbieg JR, Stivala CE, Krische MJ. Regio- and Enantioselective Iridium-Catalyzed Amination of Alkyl-Substituted Allylic Acetates with Secondary Amines. Org Lett 2022; 24:441-445. [PMID: 34905364 PMCID: PMC8764998 DOI: 10.1021/acs.orglett.1c04135] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Robust air-stable cyclometalated π-allyliridium C,O-benzoates modified by (S)-tol-BINAP catalyze the reaction of secondary aliphatic amines with racemic alkyl-substituted allylic acetates to furnish products of allylic amination with high levels of enantioselectivity. Complete branched regioselectivities were observed despite the formation of more highly substituted C-N bonds.
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90
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Andrade GC, Brancini GTP, Abe FR, de Oliveira DP, Nicolella HD, Tavares DC, Micas AFD, Savazzi EA, Silva-Junior GJ, Wainwright M, Braga GÚL. Phenothiazinium dyes for photodynamic treatment present lower environmental risk compared to a formulation of trifloxystrobin and tebuconazole. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2022; 226:112365. [PMID: 34823208 DOI: 10.1016/j.jphotobiol.2021.112365] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 11/06/2021] [Accepted: 11/11/2021] [Indexed: 06/13/2023]
Abstract
The widespread use of conventional chemical antifungal agents has led to worldwide concern regarding the selection of resistant isolates. In this scenario, antimicrobial photodynamic treatment (APDT) has emerged as a promising alternative to overcome this issue. The technique is based on the use of a photosensitizer (PS) and light in the presence of molecular oxygen. Under these conditions, the PS generates reactive oxygen species which damage the biomolecules of the target organism leading to cell death. The great potential of APDT against plant-pathogenic fungi has already been reported both in vitro and in planta, indicating this control measure has the potential to be widely used in crop plants. However, there is a lack of studies on environmental risk with ecotoxicological assessment of PSs used in APDT. Therefore, this study aimed to evaluate the environmental toxicity of four phenothiazinium PSs: i) methylene blue (MB), ii) new methylene blue N (NMBN), iii) toluidine blue O (TBO), and iv) dimethylmethylene blue (DMMB) and also of the commercial antifungal NATIVO®, a mixture of trifloxystrobin and tebuconazole. The experiments were performed with Daphnia similis neonates and zebrafish embryos. Our results showed that the PSs tested had different levels of toxicity, with MB being the less toxic and DMMB being the most. Nonetheless, the environmental toxicity of these PSs were lower when compared to that of NATIVO®. Furthermore, estimates of bioconcentration and of biotransformation half-life indicated that the PSs are environmentally safer than NATIVO®. Taken together, our results show that the toxicity associated with phenothiazinium PSs would not constitute an impediment to their use in APDT. Therefore, APDT is a promising approach to control plant-pathogenic fungi with reduced risk for selecting resistant isolates and lower environmental impacts when compared to commonly used antifungal agents.
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Tinco-Jayo JA, Aguilar-Felices EJ, Enciso-Roca EC, Arroyo-Acevedo JL, Herrera-Calderon O. Phytochemical Screening by LC-ESI-MS/MS and Effect of the Ethyl Acetate Fraction from Leaves and Stems of Jatropha macrantha Müll Arg. on Ketamine-Induced Erectile Dysfunction in Rats. Molecules 2021; 27:molecules27010115. [PMID: 35011347 PMCID: PMC8746923 DOI: 10.3390/molecules27010115] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 12/21/2021] [Accepted: 12/21/2021] [Indexed: 11/16/2022] Open
Abstract
Jatropha macrantha Müll Arg. L is also known as “huanarpo macho” and used in the Peruvian traditional medicine as an aphrodisiac and erectile dysfunction (ED). The aim of this study was to determine the phytochemical constituents in leaves and stems ethyl acetate fraction (LEAF and SEAF) of J. macrantha and to compare the antioxidant activity and the ameliorative effect on ketamine-induced erectile dysfunction in rats. The phytochemical constituents were determined by LC-ESI-MS/MS, the total phenolic compounds and total flavonoids (TPC and TF) by Folin-Ciocalteu and aluminum chloride, respectively. The antioxidant activity was determined by DPPH, ABTS, and FRAP assays. Experimental groups were divided as follows: I: negative control; II: positive control (ketamine at 50 mg/ kg/d); III: sildenafil 5 mg/kg; IV, V, VI: LEAF at 25, 50 and 100 mg/kg, respectively, and VII, VIII, IX: SEAF at 25, 50, and 100 mg/kg, respectively. The phytochemical analysis revealed the presence mainly of coumarins, flavonoids, phenolic acids, and terpenes. TPC of LEAF and SEAF were 359 ± 5.21 mg GAE/g and 306 ± 1.93 mg GAE/g, respectively; TF in LEAF and SEAF were 23.7 ± 0.80 mg EQ/g, and 101 ± 1.42 mg EQ/g, respectively. The DPPH, ABTS, FRAP in SEAF were 647 ± 3.27; 668 ± 2.30; and 575 ± 2.86 μmol TE/g, respectively, whilst LEAF showed 796 ± 3.15; 679 ± 0.85; and 806 ± 3.42 μmol TE/g, respectively. Regarding sexual behavior, LEAF showed a better effect in mount frequency, intromission frequency, ejaculation frequency, mount latency, intromission latency, ejaculatory latency, and post ejaculatory latency than SEAF. As conclusion, LEAF of J. macrantha at 50 mg/kg showed a better effect on sexual behavior in male rats with erectile dysfunction than SEAF but not higher than sildenafil.
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92
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Elzupir AO. Molecular Docking and Dynamics Investigations for Identifying Potential Inhibitors of the 3-Chymotrypsin-like Protease of SARS-CoV-2: Repurposing of Approved Pyrimidonic Pharmaceuticals for COVID-19 Treatment. Molecules 2021; 26:molecules26247458. [PMID: 34946540 PMCID: PMC8707611 DOI: 10.3390/molecules26247458] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/28/2021] [Accepted: 11/29/2021] [Indexed: 02/07/2023] Open
Abstract
This study demonstrates the inhibitory effect of 42 pyrimidonic pharmaceuticals (PPs) on the 3-chymotrypsin-like protease of SARS-CoV-2 (3CLpro) through molecular docking, molecular dynamics simulations, and free binding energies by means of molecular mechanics-Poisson Boltzmann surface area (MM-PBSA) and molecular mechanics-generalized Born surface area (MM-GBSA). Of these tested PPs, 11 drugs approved by the US Food and Drug Administration showed an excellent binding affinity to the catalytic residues of 3CLpro of His41 and Cys145: uracil mustard, cytarabine, floxuridine, trifluridine, stavudine, lamivudine, zalcitabine, telbivudine, tipiracil, citicoline, and uridine triacetate. Their percentage of residues involved in binding at the active sites ranged from 56 to 100, and their binding affinities were in the range from -4.6 ± 0.14 to -7.0 ± 0.19 kcal/mol. The molecular dynamics as determined by a 200 ns simulation run of solvated docked complexes confirmed the stability of PP conformations that bound to the catalytic dyad and the active sites of 3CLpro. The free energy of binding also demonstrates the stability of the PP-3CLpro complexes. Citicoline and uridine triacetate showed free binding energies of -25.53 and -7.07 kcal/mol, respectively. Therefore, I recommend that they be repurposed for the fight against COVID-19, following proper experimental and clinical validation.
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93
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Urumbil SK, Anilkumar MN. Anti-inflammatory activity of endophytic bacterial isolates from Emilia sonchifolia (Linn.) DC. JOURNAL OF ETHNOPHARMACOLOGY 2021; 281:114517. [PMID: 34389445 DOI: 10.1016/j.jep.2021.114517] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 08/08/2021] [Accepted: 08/09/2021] [Indexed: 06/13/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE In the traditional medicine system, plants have been utilized as a rich source of anti-microbial, anti-inflammatory, anti-cancer, anti-viral and anti-oxidant compounds. The biological properties of plant-based drugs depend on their interaction with endophytes which persist as an important provider of bioactive secondary metabolites. Bacterial endophytes secrete anti-inflammatory molecules whose activity can be the base for the anti-inflammatory property of the plant. AIM OF THE STUDY During the screening of endophytes from Emilia sonchifolia, we isolated six different bacteria whose potential as the sources of anti-inflamamtory compounds have been aimed at in this study. MATERIALS AND METHODS Anti-inflammatory activity of the ethyl acetate extract of endophytes was studied by both in vitro and in vivo analyses. In vitro study was done using protein denaturation, COX, LOX, iNOS, myeloperoxidase and nitric oxide assays and in vivo analysis was carried out by carrageenan-induced and formalin-induced paw oedema tests. The expression level of anti-inflammatory genes such as COX-2 and NfKb was confirmed by real time PCR. RESULTS We confirmed anti-inflammatory activity of the ethyl acetate extract of bacterial endophytes of E sonchifolia by both in vitro and in vivo experiments. Carrageenan- and formalin-induced inflammations in mice were effectively reduced by the administration of the bacterial extract. Among the isolates, strain ES1effectively reduced inflammation. Gene expression studies confirmed reduction in the expression of COX-2 and NfKb genes in the presence of ES1 extract. CONCLUSION The present investigation demonstrated the anti-inflammatory property of the isolated bacterial endophyte ES1 (Bacillus subtilis strain-MG 692780) and thus justifies the possible role of endophytes in contributing anti-inflammatory property to E sonchifolia which is ethno-botanically important as a source of anti-inflammatory drug.
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94
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Safrygin A, Zhmurov P, Dar’in D, Silonov S, Kasatkina M, Zonis Y, Gureev M, Krasavin M. Three-component Castagnoli-Cushman reaction with ammonium acetate delivers 2-unsubstituted isoquinol-1-ones as potent inhibitors of poly(ADP-ribose) polymerase (PARP). J Enzyme Inhib Med Chem 2021; 36:1916-1921. [PMID: 34461785 PMCID: PMC8409965 DOI: 10.1080/14756366.2021.1969386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/08/2021] [Accepted: 08/11/2021] [Indexed: 10/25/2022] Open
Abstract
An earlier described three-component variant of the Castagnoli-Cushman reaction employing homophthalic anhydrides, carbonyl compound and ammonium acetate was applied towards the preparation of 1-oxo-3,4-dihydroisoquinoline-4-carboxamides with variable substituent in position 3. These compounds displayed inhibitory activity towards poly(ADP-ribose) polymerase (PARP), a clinically validated cancer target. The most potent compound (PARP1/2 IC50 = 22/4.0 nM) displayed the highest selectivity towards PARP2 in the series (selectivity index = 5.5), more advantageous ADME prameters compared to the clinically used PARP inhibitor Olaparib.
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95
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Bretti C, Di Pietro R, Cardiano P, Gomez-Laserna O, Irto A, Lando G, De Stefano C. Thermodynamic Solution Properties of a Biodegradable Chelant (L-glutamic-N,N-diacetic Acid, L-GLDA) and Its Sequestering Ability toward Cd 2. Molecules 2021; 26:7087. [PMID: 34885669 PMCID: PMC8659045 DOI: 10.3390/molecules26237087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 11/16/2021] [Accepted: 11/18/2021] [Indexed: 11/16/2022] Open
Abstract
The thermodynamics of the interaction of L-glutamic-N,N-diacetic acid (GLDA) with protons was studied potentiometrically at different temperatures, ionic strengths and ionic media. Four protonation constants and corresponding enthalpy changes occurred at infinite dilution together with temperature and ionic strength coefficients. The medium effect was also interpreted in terms of the formation of weak complexes between the ligand and the cations of supporting electrolytes, resulting in a greater tendency of GLDA to chemically interact with Na+ rather than K+ and, in turn, (CH3)4N+. Formation constants of GLDA with Cd2+ were determined in NaCl(aq) at different ionic strength values. Five complex species were found, namely CdL2-, CdHL-, CdH2L0(aq), Cd2L0(aq), and Cd(OH)L3-, whose formation constant values at infinite dilution were log β = 12.68, 17.61, 20.76, 17.52, and 1.77, respectively. All the species results were relevant in the pH range of natural waters, although the Cd2L0(aq) was observed only for CCd ≥ CGLDA and concentrations of >0.1 mmol dm-3. The sequestering ability of GLDA toward Cd2+, evaluated by means of pL0.5, was maximum at pH~10, whereas the presence of a chloride containing a supporting electrolyte exerted a negative effect. Among new generation biodegradable ligands, GLDA was the most efficient in Cd2+ sequestration.
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Li Y, Liang J, Gao JN, Shen Y, Kuang HX, Xia YG. A novel LC-MS/MS method for complete composition analysis of polysaccharides by aldononitrile acetate and multiple reaction monitoring. Carbohydr Polym 2021; 272:118478. [PMID: 34420737 DOI: 10.1016/j.carbpol.2021.118478] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 07/18/2021] [Accepted: 07/20/2021] [Indexed: 12/11/2022]
Abstract
Carbohydrate analysis has always been a challenging task due to the occurrence of high polarity and multiple isomers. Aldoses are commonly analyzed by gas liquid chromatography (GLC) following aldononitrile acetate derivatization (AND). However, the GLC technique cannot be applied for the simultaneous determination of aldoses, ketoses, and uronic acids. In this study, a new method based on the combination of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and AND is developed for the complete characterization of monosaccharide composition (i.e., aldoses, ketoses, alditols, amino sugars, and uronic acids) in plant-derived polysaccharides. In addition to discussing the possible byproducts, the study optimizes the multiple reaction monitoring (MRM) parameters and LC conditions. The final separation of 17 carbohydrates is performed on a BEH Shield RP18 column (150 mm × 2.1 mm, 1.7 μm) within 25 min, without using any buffer salt. Notably, the complex polysaccharides extracted from Ligusticum chuanxiong, Platycodon grandiflorum, Cyathula officinalis Kuan, Juglans mandshurica Maxim, and Aralia elata (Miq.). Seem bud can be successfully characterized using the developed method. Overall, the results demonstrated that the newly established LC-MS/MS MRM method is more effective and powerful than the GLC-based methods reported previously, and it is more suitable for the analysis of highly complex natural polysaccharides, including complex pectins, fructosans, and glycoproteins.
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Alvarez AF, Rodríguez C, González-Chávez R, Georgellis D. The Escherichia coli two-component signal sensor BarA binds protonated acetate via a conserved hydrophobic-binding pocket. J Biol Chem 2021; 297:101383. [PMID: 34743001 PMCID: PMC8639471 DOI: 10.1016/j.jbc.2021.101383] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 10/27/2021] [Accepted: 11/02/2021] [Indexed: 11/11/2022] Open
Abstract
The BarA/UvrY two-component signal transduction system is widely conserved in γ-proteobacteria and provides a link between the metabolic state of the cells and the Csr posttranscriptional regulatory system. In Escherichia coli, the BarA/UvrY system responds to the presence of acetate and other short-chain carboxylic acids by activating transcription of the noncoding RNAs, CsrB and CsrC, which sequester the RNA-binding protein CsrA, a global regulator of gene expression. However, the state of the carboxyl group in the acetate molecule, which serves as the BarA stimulus, and the signal reception site of BarA remain unknown. In this study, we show that the deletion or replacement of the periplasmic domain of BarA and also the substitution of certain hydroxylated and hydrophobic amino acid residues in this region, result in a sensor kinase that remains unresponsive to its physiological stimulus, demonstrating that the periplasmic region of BarA constitutes a functional detector domain. Moreover, we provide evidence that the protonated state of acetate or formate serves as the physiological stimulus of BarA. In addition, modeling of the BarA sensor domain and prediction of the signal-binding site, by blind molecular docking, revealed a calcium channels and chemotaxis receptors domain with a conserved binding pocket, which comprised uncharged polar and hydrophobic amino acid residues. Based on the comparative sequence and phylogenetic analyses, we propose that, at least, two types of BarA orthologues diverged and evolved separately to acquire distinct signal-binding properties, illustrating the wide adaptability of the bacterial sensor kinase proteins.
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Osborne BE, Yue TTC, Waters ECT, Baark F, Southworth R, Long NJ. Synthesis and ex vivo biological evaluation of gallium-68 labelled NODAGA chelates assessing cardiac uptake and retention. Dalton Trans 2021; 50:14695-14705. [PMID: 34585706 DOI: 10.1039/d1dt02224e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Radiolabelled lipophilic cations can be used to non-invasively report on mitochondrial dysfunction in diseases such as cardiovascular disease, cardiotoxicity and cancer. Several such lipophilic cations are currently used clinically to map myocardial perfusion using SPECT imaging. Since PET offers significant advantages over SPECT in terms of sensitivity, resolution and the capacity for dynamic imaging to allow pharmacokinetic modelling, we have synthesised and radiolabelled a series of NODAGA-based radiotracers, with triarylphosphonium-functionalisation, with gallium-68 to develop PET-compatible cationic complexes. To evaluate their capacity to report upon mitochondrial membrane potential, we assessed their pharmacokinetic profiles in isolated perfused rat hearts before and after mitochondrial depolarisation with the ionophore CCCP. All three tracers radiolabel with over 96% RCY, with log D7.4 values above -0.4 observed for the most lipophilic example of this family of radiotracers. The candidate tracer [68Ga]Ga4c exhibited non-preferential uptake in healthy cardiac tissue over CCCP-infused cardiac tissue. While this approach does show promise, the lipophilicity of this family of probes needs improving in order for them to be effective cardiac imaging agents.
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Cascaval D, Galaction AI, Tucaliuc A, Kloetzer L. Direct Extraction of Fumaric Acid from Rhizopus oryzae Suspensions-Interfacial Mass Transfer. Biomolecules 2021; 11:1563. [PMID: 34827561 PMCID: PMC8615409 DOI: 10.3390/biom11111563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 10/18/2021] [Accepted: 10/19/2021] [Indexed: 11/16/2022] Open
Abstract
Experimental studies on the reactive extraction of fumaric acid with Amberlite LA-2 from Rhizopus oryzae suspensions using three solvents with different dielectric constants varying from 9.08 to 1.90 (dichloromethane, n-butyl acetate, and n-heptane, respectively) underlined the particular behavior of the extraction system in the presence of fungal biomass. The interfacial mass flow of the reaction product was found to be significantly affected by the biomass, due mainly to its adsorption onto the phase separation interface, this leading to the appearance of a physical barrier against the solute's transfer. However, the magnitude of the adsorption phenomenon was found to depend on Rhizopus oryzae's affinity for the solvent phase, which increased significantly from dichloromethane to n-heptane. The negative influence of the biomass on the interfacial mass transfer can be partially counteracted by adding 1-octanol into the organic phase, improving the solvent's ability to solve the fumaric acid-Amberlite LA-2 complex and simplifying the reactive extraction mechanism, effects that were found to be more important for low-polar solvents. Consequently, for the same mixing intensity, the maximum amplification factor was reached for n-heptane, its value being almost 5-6 times higher than that obtained for dichloromethane and over 2 times higher than that obtained with n-butyl acetate.
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Stamoulis AG, Geng P, Schmidt MA, Eastgate MD, Borovika A, Fraunhoffer KJ, Stahl SS. Sustainable Pd(OAc) 2 /Hydroquinone Cocatalyst System for Cis-Selective Dibenzoyloxylation of 1,3-Cyclohexadiene. Angew Chem Int Ed Engl 2021; 60:23182-23186. [PMID: 34399005 PMCID: PMC8511170 DOI: 10.1002/anie.202108499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Indexed: 11/08/2022]
Abstract
The 1,4-diacyloxylation of 1,3-cyclohexadiene (CHD) affords valuable stereochemically defined scaffolds for natural product and pharmaceutical synthesis. Existing cis-selective diacyloxylation protocols require superstoichiometric quantities of benzoquinone (BQ) or MnO2 , which limit process sustainability and large-scale application. In this report, reaction development and mechanistic studies are described that overcome these limitations by pairing catalytic BQ with tert-butyl hydroperoxide as the stoichiometric oxidant. Catalytic quantities of bromide enable a switch from trans to cis diastereoselectivity. A catalyst with a 1:2 Pd:Br ratio supports high cis selectivity while retaining good rate and product yield. Further studies enable replacement of BQ with hydroquinone (HQ) as a source of cocatalyst, avoiding the handling of volatile and toxic BQ in large-scale applications.
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