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Rahn HP, Liu X, Chosy MB, Sun J, Cegelski L, Wender PA. Biguanide-Vancomycin Conjugates are Effective Broad-Spectrum Antibiotics against Actively Growing and Biofilm-Associated Gram-Positive and Gram-Negative ESKAPE Pathogens and Mycobacteria. J Am Chem Soc 2024; 146:22541-22552. [PMID: 39088791 DOI: 10.1021/jacs.4c06520] [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: 08/03/2024]
Abstract
Strategies to increase the efficacy and/or expand the spectrum of activity of existing antibiotics provide a potentially fast path to clinically address the growing crisis of antibiotic-resistant infections. Here, we report the synthesis, antibacterial efficacy, and mechanistic activity of an unprecedented class of biguanide-antibiotic conjugates. Our lead biguanide-vancomycin conjugate, V-C6-Bg-PhCl (5e), induces highly effective cell killing with up to a 2 orders-of-magnitude improvement over its parent compound, vancomycin (V), against vancomycin-resistant enterococcus. V-C6-Bg-PhCl (5e) also exhibits improved activity against mycobacteria and each of the ESKAPE pathogens, including the Gram-negative organisms. Furthermore, we uncover broad-spectrum killing activity against biofilm-associated Gram-positive and Gram-negative bacteria as well as mycobacteria not observed for clinically used antibiotics such as oritavancin. Mode-of-action studies reveal that vancomycin-like cell wall synthesis inhibition with improved efficacy attributed to enhanced engagement at vancomycin binding sites through biguanide association with relevant cell-surface anions for Gram-positive and Gram-negative bacteria. Due to its potency, remarkably broad activity, and lack of acute mammalian cell toxicity, V-C6-Bg-PhCl (5e) is a promising candidate for treating antibiotic-resistant infections and notoriously difficult-to-treat slowly growing and antibiotic-tolerant bacteria associated with chronic and often incurable infections. More generally, this study offers a new strategy (biguanidinylation) to enhance antibiotic activity and facilitate clinical entry.
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Affiliation(s)
- Harrison P Rahn
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Xinyu Liu
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Madeline B Chosy
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Jiuzhi Sun
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Lynette Cegelski
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Paul A Wender
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Department of Chemical and Systems Biology, Stanford University, Stanford, California 94305, United States
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2
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Rzycki M, Drabik D. Multifaceted Activity of Fabimycin: Insights from Molecular Dynamics Studies on Bacterial Membrane Models. J Chem Inf Model 2024; 64:4204-4217. [PMID: 38733348 PMCID: PMC11134499 DOI: 10.1021/acs.jcim.4c00228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 04/29/2024] [Accepted: 04/30/2024] [Indexed: 05/13/2024]
Abstract
Membranes─cells' essential scaffolds─are valid molecular targets for substances with an antimicrobial effect. While certain substances, such as octenidine, have been developed to target membranes for antimicrobial purposes, the recently reported molecule, fabimycin (F2B)─a novel agent targeting drug-resistant Gram-negative bacteria─has not received adequate attention regarding its activity on membranes in the literature. The following study aims to investigate the effects of F2B on different bacterial membrane models, including simple planar bilayers and more complex bilayer systems that mimic the Escherichia coli shell equipped with double inner and outer bilayers. Our results show that F2B exhibited more pronounced interactions with bacterial membrane systems compared to the control PC system. Furthermore, we observed significant changes in local membrane property homeostasis in both the inner and outer membrane models, specifically in the case of lateral diffusion, membrane thickness, and membrane resilience (compressibility, tilt). Finally, our results showed that the effect of F2B differed in a complex system and a single membrane system. Our study provides new insights into the multifaceted activity of F2B, demonstrating its potential to disrupt bacterial membrane homeostasis, indicating that its activity extends the currently known mechanism of FabI enzyme inhibition. This disruption, coupled with the ability of F2B to penetrate the outer membrane layers, sheds new light on the behavior of this antimicrobial molecule. This highlights the importance of the interaction with the membrane, crucial in combating bacterial infections, particularly those caused by drug-resistant strains.
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Affiliation(s)
- Mateusz Rzycki
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw 50-370, Poland
| | - Dominik Drabik
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw 50-370, Poland
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3
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Herráiz Soria E, Alou L, Martin-Villa C, Becerro-de-Bengoa-Vallejo R, Losa-Iglesias M, Sevillano D. Alcohol-Based Chlorhexidine and Potassium Sorbate Rub Strengthens the Effectiveness of Traditional Hand Scrubbing and Improves Long-Lasting Effectiveness-Evaluation of Hand Preparation Protocols According to EN 12791. Antibiotics (Basel) 2024; 13:470. [PMID: 38786198 PMCID: PMC11117658 DOI: 10.3390/antibiotics13050470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 05/17/2024] [Accepted: 05/17/2024] [Indexed: 05/25/2024] Open
Abstract
Despite the advantages of surgical handrub in terms of the ease of application and effectiveness, chlorhexidine (CHG)-based hand scrubbing remains the preferred method for surgical hand preparation. However, it does not systematically meet the non-inferiority requirement of the European norm (EN) 12791 with respect to n-propanol (the reference product) and does not provide the sustained efficacy expected for these long-lasting agents. Commercially available alcohol-based products have also failed to demonstrate sustained efficacy according to EN 12791. Multi-step protocols enhance the efficacy of hand scrubbing, yet their extended disinfection duration might diminish their allure for healthcare professionals. In this study, we show that hand scrubbing with CHG 4% followed by a 1 min rubbing with the novel formulation of ethanol (Et) 70%/CHG 3% plus 0.3% potassium sorbate food additive (PS) meets the non-inferiority requirement and demonstrates sustained efficacy when tested according to EN 12791. The immediate and 3 h effect of this protocol was significantly higher than that of n-propanol and the homologous disinfection protocol without PS (CHG 4% hand scrub plus Et 70%/CHG 3% rub), demonstrating that the inclusion of PS confers a notable residual effect. We speculate that this non-volatile ingredient acts synergistically with CHG. This promising combination represents an alternative method for the development of new disinfection strategies.
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Affiliation(s)
- Elena Herráiz Soria
- Faculty of Health Sciences, Universidad Rey Juan Carlos, 28933 Madrid, Spain; (E.H.S.); (M.L.-I.)
| | - Luis Alou
- Microbiology Area-Medicine Department, School of Medicine, Universidad Complutense de Madrid, 28040 Madrid, Spain;
| | - Carlos Martin-Villa
- Faculty of Nursing, Physiotherapy and Podiatry, Universidad Complutense de Madrid, 28040 Madrid, Spain; (C.M.-V.); (R.B.-d.-B.-V.)
| | | | - Marta Losa-Iglesias
- Faculty of Health Sciences, Universidad Rey Juan Carlos, 28933 Madrid, Spain; (E.H.S.); (M.L.-I.)
| | - David Sevillano
- Microbiology Area-Medicine Department, School of Medicine, Universidad Complutense de Madrid, 28040 Madrid, Spain;
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4
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Paschenko VZ, Lukashev EP, Mamedov MD, Gvozdev DA, Knox PP. Effect of cationic antiseptics on fluorescent characteristics and electron transfer in cyanobacterial photosystem I complexes. PHOTOSYNTHESIS RESEARCH 2024; 159:241-251. [PMID: 37480468 DOI: 10.1007/s11120-023-01039-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 07/09/2023] [Indexed: 07/24/2023]
Abstract
In this study, the effects of cationic antiseptics such as chlorhexidine, picloxidine, miramistin, and octenidine at concentrations up to 150 µM on fluorescence spectra and its lifetimes, as well as on light-induced electron transfer in protein-pigment complexes of photosystem I (PSI) isolated from cyanobacterium Synechocystis sp. PCC 6803 have been studied. In doing so, octenidine turned out to be the most "effective" in terms of its influence on the spectral and functional characteristics of PSI complexes. It has been shown that the rate of energy migration from short-wavelength forms of light-harvesting chlorophyll to long-wavelength ones slows down upon addition of octenidine to the PSI suspension. After photo-separation of charges between the primary electron donor P700 and the terminal iron-sulfur center(s) FA/FB, the rate of forward electron transfer from (FA/FB)- to the external medium slows down while the rate of charge recombination between reduced FA/FB- and photooxidized P700+ increases. The paper considers the possible causes of the observed action of the antiseptic.
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Affiliation(s)
- Vladimir Z Paschenko
- Biophysical Department, Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskye Gory 1, Build. 12, Moscow, Russia, 119234
| | - Eugene P Lukashev
- Biophysical Department, Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskye Gory 1, Build. 12, Moscow, Russia, 119234
| | - Mahir D Mamedov
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Leninskye Gory 1, Build. 40, Moscow, Russia, 119992
| | - Daniil A Gvozdev
- Biophysical Department, Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskye Gory 1, Build. 12, Moscow, Russia, 119234.
| | - Peter P Knox
- Biophysical Department, Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskye Gory 1, Build. 12, Moscow, Russia, 119234
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5
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Rzycki M, Gładysiewicz-Kudrawiec M, Kraszewski S. Molecular guidelines for promising antimicrobial agents. Sci Rep 2024; 14:4641. [PMID: 38409391 DOI: 10.1038/s41598-024-55418-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 02/23/2024] [Indexed: 02/28/2024] Open
Abstract
Antimicrobial resistance presents a pressing challenge to public health, which requires the search for novel antimicrobial agents. Various experimental and theoretical methods are employed to understand drug-target interactions and propose multistep solutions. Nonetheless, efficient screening of drug databases requires rapid and precise numerical analysis to validate antimicrobial efficacy. Diptool addresses this need by predicting free energy barriers and local minima for drug translocation across lipid membranes. In the current study employing Diptool free energy predictions, the thermodynamic commonalities between selected antimicrobial molecules were characterized and investigated. To this end, various clustering methods were used to identify promising groups with antimicrobial activity. Furthermore, the molecular fingerprinting and machine learning approach (ML) revealed common structural elements and physicochemical parameters in these clusters, such as long carbon chains, charged ammonium groups, and low dipole moments. This led to the establishment of guidelines for the selection of effective antimicrobial candidates based on partition coefficients (logP) and molecular mass ranges. These guidelines were implemented within the Reinforcement Learning for Structural Evolution (ReLeaSE) framework, generating new chemicals with desired properties. Interestingly, ReLeaSE produced molecules with structural profiles similar to the antimicrobial agents tested, confirming the importance of the identified features. In conclusion, this study demonstrates the ability of molecular fingerprinting and AI-driven methods to identify promising antimicrobial agents with a broad range of properties. These findings deliver substantial implications for the development of antimicrobial drugs and the ongoing battle against antibiotic-resistant bacteria.
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Affiliation(s)
- Mateusz Rzycki
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, 50-370, Wroclaw, Poland.
| | | | - Sebastian Kraszewski
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, 50-370, Wroclaw, Poland
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6
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Wainwright M. Photosensitised versus conventional infection control: the local fight continues. Photochem Photobiol Sci 2024; 23:23-29. [PMID: 38095821 DOI: 10.1007/s43630-023-00503-4] [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: 08/23/2023] [Accepted: 11/04/2023] [Indexed: 02/02/2024]
Abstract
The worsening problem of antimicrobial drug resistance requires a nuanced approach. Since the conventional drug pipeline is unlikely to be sufficient to avoid massive increases in mortality by the mid-twenty-first century, other methods of antisepsis will be required. These might be used either in place of (allowing conservation) or together with conventional agents. Of such approaches, locally applied protocols involving photo-antimicrobials suggest themselves, particularly as early intervention, e.g. in bacterial tonsillitis, would be curative without recourse to conventional drugs, and would thus prevent the development of more serious diseases such as pneumonia or meningitis. However, given the pharmaceutical industry's lack of investment in such approaches, support would be required from other areas of bioscience, such as the biomed or biotech sectors.
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7
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Fang T, Xiong J, Wang L, Feng Z, Hang S, Yu J, Li W, Feng Y, Lu H, Jiang Y. Unexpected Inhibitory Effect of Octenidine Dihydrochloride on Candida albicans Filamentation by Impairing Ergosterol Biosynthesis and Disrupting Cell Membrane Integrity. Antibiotics (Basel) 2023; 12:1675. [PMID: 38136708 PMCID: PMC10741164 DOI: 10.3390/antibiotics12121675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 11/20/2023] [Accepted: 11/25/2023] [Indexed: 12/24/2023] Open
Abstract
Candida albicans filamentation plays a significant role in developing both mucosal and invasive candidiasis, making it a crucial virulence factor. Consequently, exploring and identifying inhibitors that impede fungal hyphal formation presents an intriguing approach toward antifungal strategies. In line with this anti-filamentation strategy, we conducted a comprehensive screening of a library of FDA-approved drugs to identify compounds that possess inhibitory properties against hyphal growth. The compound octenidine dihydrochloride (OCT) exhibits potent inhibition of hyphal growth in C. albicans across different hyphae-inducing media at concentrations below or equal to 3.125 μM. This remarkable inhibitory effect extends to biofilm formation and the disruption of mature biofilm. The mechanism underlying OCT's inhibition of hyphal growth is likely attributed to its capacity to impede ergosterol biosynthesis and induce the generation of reactive oxygen species (ROS), compromising the integrity of the cell membrane. Furthermore, it has been observed that OCT demonstrates protective attributes against invasive candidiasis in Galleria mellonella larvae through its proficient eradication of C. albicans colonization in infected G. mellonella larvae by impeding hyphal formation. Although additional investigation is required to mitigate the toxicity of OCT in mammals, it possesses considerable promise as a potent filamentation inhibitor against invasive candidiasis.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Hui Lu
- Department of Pharmacy, Shanghai Tenth People’s Hospital, School of Medicine, Tongji University, Shanghai 200072, China
| | - Yuanying Jiang
- Department of Pharmacy, Shanghai Tenth People’s Hospital, School of Medicine, Tongji University, Shanghai 200072, China
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8
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Singer L, Karacic S, Szekat C, Bierbaum G, Bourauel C. Biological properties of experimental dental alginate modified for self-disinfection using green nanotechnology. Clin Oral Investig 2023; 27:6677-6688. [PMID: 37775587 PMCID: PMC10630233 DOI: 10.1007/s00784-023-05277-8] [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: 07/06/2023] [Accepted: 09/23/2023] [Indexed: 10/01/2023]
Abstract
OBJECTIVES Disinfection of alginate impression materials is a mandatory step to prevent cross-infection in dental clinics. However, alginate disinfection methods are time-consuming and exert a negative impact on accuracy and mechanical properties. Thus, this study aimed to prepare disinfecting agents (CHX and AgNO3) and silver nanoparticles reduced by a natural plant extract to produce a self-disinfecting dental alginate. METHODS Conventional alginate impression material was used in this study. Silver nitrate (0.2% AgNO3 group) and chlorohexidine (0.2% CHX group) solutions were prepared using distilled water, and these solutions were later employed for alginate preparation. Moreover, a 90% aqueous plant extract was prepared from Boswellia sacra (BS) oleoresin and used to reduce silver nitrate to form silver nanoparticles that were incorporated in the dental alginate preparation (BS+AgNPs group). The plant extract was characterized by gas chromatography/mass spectrometry (GC/MS) analysis while green-synthesized silver nanoparticles (AgNPs) were characterized by UV-visible (UV-vis) spectroscopy and scanning electron microscopy (SEM). An agar disc diffusion assay was used to test the antimicrobial activity against Candida albicans, Streptococcus mutans, Escherichia coli, methicillin-resistant and susceptible Staphylococcus aureus strains, and Micrococcus luteus. Agar plates were incubated at 37 ± 1 °C for 24 h to allow microbial growth. Diameters of the circular inhibition zones formed around each specimen were measured digitally by using ImageJ software. RESULTS Chemical analysis of the plant extract revealed the presence of 41 volatile and semi-volatile active compounds. UV-Vis spectrophotometry, SEM, and EDX confirmed the formation of spherical silver nanoparticles using the BS extract. CHX, AgNO3, and the BS+AgNPs modified groups showed significantly larger inhibition zones than the control group against all tested strains. BS+AgNPs and CHX groups showed comparable efficacy against all tested strains except for Staphylococcus aureus, where the CHX-modified alginate had a significantly higher effect. CONCLUSIONS AND CLINICAL RELEVANCE CHX, silver nitrate, and biosynthesized silver nanoparticles could be promising inexpensive potential candidates for the preparation of a self-disinfecting alginate impression material without affecting its performance. Green synthesis of metal nanoparticles using Boswellia sacra extract could be a very safe, efficient, and nontoxic way with the additional advantage of a synergistic action between metal ions and the phytotherapeutic agents of the plant extract.
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Affiliation(s)
- Lamia Singer
- Oral Technology, Medical Faculty, University Hospital Bonn, Bonn, Germany.
- Department of Orthodontics, Medical Faculty, University Hospital Bonn, Bonn, Germany.
| | - Sabina Karacic
- Institute of Medical Microbiology, Immunology, and Parasitology, Medical Faculty, University Hospital Bonn, 53127, Bonn, North Rhine-Westphalia, Germany
| | - Christiane Szekat
- Institute of Medical Microbiology, Immunology, and Parasitology, Medical Faculty, University Hospital Bonn, 53127, Bonn, North Rhine-Westphalia, Germany
| | - Gabriele Bierbaum
- Institute of Medical Microbiology, Immunology, and Parasitology, Medical Faculty, University Hospital Bonn, 53127, Bonn, North Rhine-Westphalia, Germany
| | - Christoph Bourauel
- Oral Technology, Medical Faculty, University Hospital Bonn, Bonn, Germany
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9
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Garrido L, Lyra P, Rodrigues J, Viana J, Mendes JJ, Barroso H. Revisiting Oral Antiseptics, Microorganism Targets and Effectiveness. J Pers Med 2023; 13:1332. [PMID: 37763100 PMCID: PMC10532628 DOI: 10.3390/jpm13091332] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 08/24/2023] [Accepted: 08/27/2023] [Indexed: 09/29/2023] Open
Abstract
A good oral health status is mostly dependent on good oral hygiene habits, which knowingly impacts systemic health. Although controversial, chemical oral antiseptics can be useful in adjunct use to mechanical dental plaque control techniques in the prevention and management of local and overall health and well-being. This review aims to revisit, gather and update evidence-based clinical indications for the use of the most popular oral antiseptics, considering different types, microorganism targets and effectiveness in order to establish updated clinical recommendations.
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Affiliation(s)
| | | | | | | | | | - Helena Barroso
- Egas Moniz Center for Interdisciplinary Research (CiiEM), Egas Moniz School of Health & Science, Caparica, 2829-511 Almada, Portugal (P.L.); (J.V.); (J.J.M.)
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10
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Waller C, Marzinek JK, McBurnie E, Bond PJ, Williamson PTF, Khalid S. Impact on S. aureus and E. coli Membranes of Treatment with Chlorhexidine and Alcohol Solutions: Insights from Molecular Simulations and Nuclear Magnetic Resonance. J Mol Biol 2023; 435:167953. [PMID: 37330283 DOI: 10.1016/j.jmb.2023.167953] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Revised: 12/16/2022] [Accepted: 01/04/2023] [Indexed: 06/19/2023]
Abstract
Membranes form the first line of defence of bacteria against potentially harmful molecules in the surrounding environment. Understanding the protective properties of these membranes represents an important step towards development of targeted anti-bacterial agents such as sanitizers. Use of propanol, isopropanol and chlorhexidine can significantly decrease the threat imposed by bacteria in the face of growing anti-bacterial resistance via mechanisms that include membrane disruption. Here we have employed molecular dynamics simulations and nuclear magnetic resonance to explore the impact of chlorhexidine and alcohol on the S. aureus cell membrane, as well as the E. coli inner and outer membranes. We identify how sanitizer components partition into these bacterial membranes, and show that chlorhexidine is instrumental in this process.
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Affiliation(s)
- Callum Waller
- School of Chemistry, University of Southampton, SO17 1BJ, UK; Bioinformatics Institute, 30 Biopolis Street, Singapore 138671, Singapore
| | - Jan K Marzinek
- Bioinformatics Institute, 30 Biopolis Street, Singapore 138671, Singapore
| | - Eilish McBurnie
- School of Chemistry, University of Southampton, SO17 1BJ, UK; Bioinformatics Institute, 30 Biopolis Street, Singapore 138671, Singapore
| | - Peter J Bond
- Bioinformatics Institute, 30 Biopolis Street, Singapore 138671, Singapore; National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | | | - Syma Khalid
- School of Chemistry, University of Southampton, SO17 1BJ, UK; Department of Biochemistry, University of Oxford, OX1 3QU, UK.
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11
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Paschenko VZ, Lukashev EP, Mamedov MD, Korvatovskiy BN, Knox PP. Influence of the antiseptic octenidine on spectral characteristics and energy migration processes in photosystem II core complexes. PHOTOSYNTHESIS RESEARCH 2023; 155:93-105. [PMID: 36335236 PMCID: PMC9638271 DOI: 10.1007/s11120-022-00972-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Accepted: 09/29/2022] [Indexed: 06/16/2023]
Abstract
Herein, the effect of cationic antiseptics (chlorhexidine, picloxidine, miramistin, octenidine) on the initial processes of the delivery of light energy and its efficient use by the reaction centers in intact spinach photosystem II core complexes has been investigated. The characteristic effects-an increase in the fluorescence yield of light-harvesting pigments and a slowdown in the rate of energy migration in bacterial photosynthetic chromatophores has been recently demonstrated mainly in the presence of octenidine (Strakhovskaya et al., in Photosynth Res 147:197-209, 2021; Knox et al., in Photosynth Res, https://doi.org/10.1007/s11120-022-00909-8 , 2022). In this study, we also observed that in the presence of octenidine, the fluorescence intensity of photosystem II core complexes increases by 5-10 times, and the rate of energy migration from antennae to the reaction centers decreases by 3 times. In addition, with an increase in the concentration of this antiseptic, a new effect related to a shift of the spectrum, absorption and fluorescence to the short-wavelength region has been found. Similar effects were observed when detergent Triton X-100 was added to photosystem II samples. We concluded that the antiseptic primarily affects the structure of the internal light-harvesting antenna (CP43 and CP47), through which the excitation energy is delivered to the reaction center. As a result of such an impact, the chlorophyll molecules in this structure are destabilized and their optical and functional characteristics change.
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Affiliation(s)
- Vladimir Z Paschenko
- Biophysical Department, Faculty of Biology, M.V.Lomonosov Moscow State University, Leninskye Gory 1, Build. 12, Moscow, Russia, 119234
| | - Eugene P Lukashev
- Biophysical Department, Faculty of Biology, M.V.Lomonosov Moscow State University, Leninskye Gory 1, Build. 12, Moscow, Russia, 119234
| | - Mahir D Mamedov
- A.N.Belozersky Institute of Physico-Chemical Biology, Moscow State University, Leninskye Gory 1, Build. 40, Moscow, Russia, 119992
| | - Boris N Korvatovskiy
- Biophysical Department, Faculty of Biology, M.V.Lomonosov Moscow State University, Leninskye Gory 1, Build. 12, Moscow, Russia, 119234
| | - Peter P Knox
- Biophysical Department, Faculty of Biology, M.V.Lomonosov Moscow State University, Leninskye Gory 1, Build. 12, Moscow, Russia, 119234.
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12
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Vejzovic D, Iftic A, Ön A, Semeraro EF, Malanovic N. Octenidine's Efficacy: A Matter of Interpretation or the Influence of Experimental Setups? Antibiotics (Basel) 2022; 11:1665. [PMID: 36421309 PMCID: PMC9686575 DOI: 10.3390/antibiotics11111665] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/14/2022] [Accepted: 11/15/2022] [Indexed: 07/30/2023] Open
Abstract
With its broad antimicrobial spectrum and non-specific mode of action via membrane disruption, any resistance to octenidine (OCT) seems unlikely and has not been observed in clinical settings so far. In this study, we aimed to investigate the efficacy of OCT against Escherichia coli and mutants lacking specific lipid head groups which, due to altered membrane properties, might be the root cause for resistance development of membrane-active compounds. Furthermore, we aimed to test its efficacy under different experimental conditions including different solvents for OCT, bacterial concentration and methods for analysis. Our primary goal was to estimate how many OCT molecules are needed to kill one bacterium. We performed susceptibility assays by observing bacterial growth behavior, using a Bioscreen in an analogous manner for every condition. The growth curves were recorded for 20 h at 420-580 nm in presence of different OCT concentrations and were used to assess the inhibitory concentrations (IC100%) for OCT. Bacterial concentrations given in cell numbers were determined, followed by Bioscreen measurement by manual colony counting on agar plates and QUANTOMTM cell staining. This indicated a significant variance between both methods, which influenced IC100% of OCT, especially when used at low doses. The binding capacity of OCT to E. coli was investigated by measuring UV-absorbance of OCT exposed to bacteria and a common thermodynamic framework based on Bioscreen measurements. Results showed that OCT's antimicrobial activity in E. coli is not affected by changes at the membrane level but strongly dependent on experimental settings in respect to solvents and applied bacterial counts. More OCT was required when the active was dissolved in phosphate or Hepes buffers instead of water and when higher bacterial concentration was used. Furthermore, binding studies revealed that 107-108 OCT molecules bind to bacteria, which is necessary for the saturation of the bacterial surface to initiate the killing cascade. Our results clearly demonstrate that in vitro data, depending on the applied materials and the methods for determination of IC100%, can easily be misinterpreted as reduced bacterial susceptibility towards OCT.
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Affiliation(s)
- Djenana Vejzovic
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Azra Iftic
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Ayse Ön
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Enrico F. Semeraro
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
- Field of Excellence BioHealth, University of Graz, 8010 Graz, Austria
- Bio TechMed Graz, 8010 Graz, Austria
| | - Nermina Malanovic
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria
- Field of Excellence BioHealth, University of Graz, 8010 Graz, Austria
- Bio TechMed Graz, 8010 Graz, Austria
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13
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Gray BH, Green KJ, Haines RR, Hammer KA. Antibacterial interactions between two monofloral honeys and several topical antiseptics, including essential oils. BMC Complement Med Ther 2022; 22:228. [PMID: 36028831 PMCID: PMC9419324 DOI: 10.1186/s12906-022-03695-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Accepted: 08/03/2022] [Indexed: 11/13/2022] Open
Abstract
Background Honey has broad spectrum antibacterial activity against clinically important organisms and may be suitable for treating superficial bacterial infections. However, very little data are available describing potential interactions between honey and other topically applied agents such as antiseptics or essential oils. Methods Interactions between pairs of antibacterial agents were investigated by performing checkerboard assays and determining the fractional inhibitory concentration indices (FICIs). Interactions between the two monofloral honeys marri (from Corymbia calophylla) and manuka, and the antiseptic agents benzalkonium chloride, chlorhexidine digluconate, silver (I) nitrate, tea tree oil, and Eucalyptus polybractea oil were investigated against Staphylococcus aureus ATCC® 43300 and Pseudomonas aeruginosa ATCC® 27853. Results Additive or indifferent interactions (FICI 0.5—2) were observed for all combinations against both organisms tested, with the exception of chlorhexidine and honey. Chlorhexidine and marri honey showed an antagonistic relationship against S. aureus (median FICI 2.00, range 1.25—4.83). Similarly, chlorhexidine and manuka honey showed antagonism against S. aureus (median FICI 2.33, range 2.00—2.67). Conclusions With the exception of chlorhexidine, these data indicate that honey does not interfere with the antimicrobial activity of the tested agents, and that honey may be suitable for combination therapy with other topically applied antibacterial agents for treating superficial bacterial infections. Supplementary Information The online version contains supplementary material available at 10.1186/s12906-022-03695-x.
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Farthing K, Wares KD, Siani H. When 2% Chlorhexidine isn't 2%! Implications on MRSA Decolonisation Guidelines. J Hosp Infect 2022; 127:133-134. [PMID: 35724952 DOI: 10.1016/j.jhin.2022.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 06/13/2022] [Indexed: 11/28/2022]
Affiliation(s)
| | - Karen D Wares
- GAMA Healthcare Ltd, UK; School of Nursing and Midwifery, University of Newcastle, Ourimbah, New South Wales, 2258, Australia
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15
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Disruption of the Cytoplasmic Membrane Structure and Barrier Function Underlies the Potent Antiseptic Activity of Octenidine in Gram-Positive Bacteria. Appl Environ Microbiol 2022; 88:e0018022. [PMID: 35481757 PMCID: PMC9128513 DOI: 10.1128/aem.00180-22] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The antimicrobial killing mechanism of octenidine (OCT), a well-known antiseptic is poorly understood. We recently reported its interaction with Gram-negative bacteria by insertion of OCT into the outer and cytoplasmic membrane of Escherichia coli, resulting in a chaotic lipid rearrangement and rapid disruption of the cell envelope. Its action primarily disturbs the packing order of the hydrophobic moiety of a lipid, which consequently might result in a cascade of multiple effects at a cellular level. Here, we investigated OCT's impact on two different Gram-positive bacteria, Enterococcus hirae and Bacillus subtilis, and their respective model membranes. In accordance with our previous results, OCT induced membrane disorder in all investigated model systems. Electron and fluorescence microscopy clearly demonstrated changes in cellular structure and membrane integrity. These changes were accompanied by neutralization of the surface charge in both E. hirae and B. subtilis and membrane disturbances associated with permeabilization. Similar permeabilization and disordering of the lipid bilayer was also observed in model membranes. Furthermore, experiments performed on strongly versus partly anionic membranes showed that the lipid disordering effect induced by OCT is a result of maximized hydrophobic over electrostatic forces without distinct neutralization of the surface charge or discrimination between the lipid head groups. Indeed, mutants lacking specific lipid head groups were also susceptible to OCT to a similar extent as the wild type. The observed unspecific mode of action of OCT underlines its broad antimicrobial profile and renders the development of bacterial resistance to this molecule less likely. IMPORTANCE OCT is a well-established antiseptic molecule routinely used in a large field of clinical applications. Since the spread of antimicrobial resistance has restricted the use of antibiotics worldwide, topically applied antiseptics like OCT, with a broad spectrum of antimicrobial activity and high safety profile, gain increasing importance for effective infection prevention and therapy. To eliminate a wide spectrum of disease-causing microorganisms, a compound's antiseptic activity should be unspecific or multitarget. Our results demonstrate an unspecific mechanism of action for OCT, which remained largely unknown for years. OCT disturbs the barrier function of a bacterial cell, a function that is absolutely fundamental for survival. Because OCT does not distinguish between lipids, the building blocks of bacterial membranes, its mode of action might be attributed to all bacteria, including (multi)drug-resistant isolates. Our results underpin OCT's potent antiseptic activity for successful patient outcome.
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Fox LJ, Kelly PP, Humphreys GJ, Waigh T, Lu JR, McBain AJ. Assessing the Risk of Resistance to Cationic Biocides incorporating Realism-based and Biophysical Approaches. J Ind Microbiol Biotechnol 2021; 49:6414534. [PMID: 34718634 PMCID: PMC9113109 DOI: 10.1093/jimb/kuab074] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 09/27/2021] [Indexed: 12/30/2022]
Abstract
The control of microorganisms is a key objective in disease prevention and in medical, industrial, domestic, and food-production environments. Whilst the effectiveness of biocides in these contexts is well-evidenced, debate continues about the resistance risks associated with their use. This has driven an increased regulatory burden, which in turn could result in a reduction of both the deployment of current biocides and the development of new compounds and formulas. Efforts to balance risk and benefit are therefore of critical importance and should be underpinned by realistic methods and a multi-disciplinary approach, and through objective and critical analyses of the literature. The current literature on this topic can be difficult to navigate. Much of the evidence for potential issues of resistance generation by biocides is based on either correlation analysis of isolated bacteria, where reports of treatment failure are generally uncommon, or laboratory studies that do not necessarily represent real biocide applications. This is complicated by inconsistencies in the definition of the term resistance. Similar uncertainties also apply to cross-resistance between biocides and antibiotics. Risk assessment studies that can better inform practice are required. The resulting knowledge can be utilised by multiple stakeholders including those tasked with new product development, regulatory authorities, clinical practitioners, and the public. This review considers current evidence for resistance and cross-resistance and outlines efforts to increase realism in risk assessment. This is done in the background of the discussion of the mode of application of biocides and the demonstrable benefits as well as the potential risks.
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Affiliation(s)
- Laura J Fox
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, United Kingdom
| | - Paul P Kelly
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, United Kingdom
| | - Gavin J Humphreys
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, United Kingdom
| | - Thomas Waigh
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, United Kingdom
| | - Jian R Lu
- Biological Physics Laboratory, Department of Physics and Astronomy, Faculty of Science and Engineering, The University of Manchester, United Kingdom
| | - Andrew J McBain
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, United Kingdom
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Rzycki M, Kraszewski S, Gładysiewicz-Kudrawiec M. Diptool-A Novel Numerical Tool for Membrane Interactions Analysis, Applying to Antimicrobial Detergents and Drug Delivery Aids. MATERIALS (BASEL, SWITZERLAND) 2021; 14:6455. [PMID: 34771982 PMCID: PMC8585202 DOI: 10.3390/ma14216455] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 10/23/2021] [Accepted: 10/25/2021] [Indexed: 11/17/2022]
Abstract
The widespread problem of resistance development in bacteria has become a critical issue for modern medicine. To limit that phenomenon, many compounds have been extensively studied. Among them were derivatives of available drugs, but also alternative novel detergents such as Gemini surfactants. Over the last decade, they have been massively synthesized and studied to obtain the most effective antimicrobial agents, as well as the most selective aids for nanoparticles drug delivery. Various protocols and distinct bacterial strains used in Minimal Inhibitory Concentration experimental studies prevented performance benchmarking of different surfactant classes over these last years. Motivated by this limitation, we designed a theoretical methodology implemented in custom fast screening software to assess the surfactant activity on model lipid membranes. Experimentally based QSAR (quantitative structure-activity relationship) prediction delivered a set of parameters underlying the Diptool software engine for high-throughput agent-membrane interactions analysis. We validated our software by comparing score energy profiles with Gibbs free energy from the Adaptive Biasing Force approach on octenidine and chlorhexidine, popular antimicrobials. Results from Diptool can reflect the molecule behavior in the lipid membrane and correctly predict free energy of translocation much faster than classic molecular dynamics. This opens a new venue for searching novel classes of detergents with sharp biologic activity.
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Affiliation(s)
- Mateusz Rzycki
- Department of Experimental Physics, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland;
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland;
| | - Sebastian Kraszewski
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland;
| | - Marta Gładysiewicz-Kudrawiec
- Department of Experimental Physics, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland;
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Róg T, Girych M, Bunker A. Mechanistic Understanding from Molecular Dynamics in Pharmaceutical Research 2: Lipid Membrane in Drug Design. Pharmaceuticals (Basel) 2021; 14:1062. [PMID: 34681286 PMCID: PMC8537670 DOI: 10.3390/ph14101062] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/14/2021] [Accepted: 10/15/2021] [Indexed: 11/17/2022] Open
Abstract
We review the use of molecular dynamics (MD) simulation as a drug design tool in the context of the role that the lipid membrane can play in drug action, i.e., the interaction between candidate drug molecules and lipid membranes. In the standard "lock and key" paradigm, only the interaction between the drug and a specific active site of a specific protein is considered; the environment in which the drug acts is, from a biophysical perspective, far more complex than this. The possible mechanisms though which a drug can be designed to tinker with physiological processes are significantly broader than merely fitting to a single active site of a single protein. In this paper, we focus on the role of the lipid membrane, arguably the most important element outside the proteins themselves, as a case study. We discuss work that has been carried out, using MD simulation, concerning the transfection of drugs through membranes that act as biological barriers in the path of the drugs, the behavior of drug molecules within membranes, how their collective behavior can affect the structure and properties of the membrane and, finally, the role lipid membranes, to which the vast majority of drug target proteins are associated, can play in mediating the interaction between drug and target protein. This review paper is the second in a two-part series covering MD simulation as a tool in pharmaceutical research; both are designed as pedagogical review papers aimed at both pharmaceutical scientists interested in exploring how the tool of MD simulation can be applied to their research and computational scientists interested in exploring the possibility of a pharmaceutical context for their research.
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Affiliation(s)
- Tomasz Róg
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland;
| | - Mykhailo Girych
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland;
| | - Alex Bunker
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, 00014 Helsinki, Finland;
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Rzycki M, Kaczorowska A, Kraszewski S, Drabik D. A Systematic Approach: Molecular Dynamics Study and Parametrisation of Gemini Type Cationic Surfactants. Int J Mol Sci 2021; 22:ijms222010939. [PMID: 34681599 PMCID: PMC8536075 DOI: 10.3390/ijms222010939] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/04/2021] [Accepted: 10/08/2021] [Indexed: 01/07/2023] Open
Abstract
The spreading of antibiotic-resistant bacteria strains is one of the most serious problem in medicine to struggle nowadays. This triggered the development of alternative antimicrobial agents in recent years. One of such group is Gemini surfactants which are massively synthesised in various structural configurations to obtain the most effective antibacterial properties. Unfortunately, the comparison of antimicrobial effectiveness among different types of Gemini agents is unfeasible since various protocols for the determination of Minimum Inhibitory Concentration are used. In this work, we proposed alternative, computational, approach for such comparison. We designed a comprehensive database of 250 Gemini surfactants. Description of structure parameters, for instance spacer type and length, are included in the database. We parametrised modelled molecules to obtain force fields for the entire Gemini database. This was used to conduct in silico studies using the molecular dynamics to investigate the incorporation of these agents into model E. coli inner membrane system. We evaluated the effect of Gemini surfactants on structural, stress and mechanical parameters of the membrane after the agent incorporation. This enabled us to select four most likely membrane properties that could correspond to Gemini’s antimicrobial effect. Based on our results we selected several types of Gemini spacers which could demonstrate a particularly strong effect on the bacterial membranes.
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Affiliation(s)
- Mateusz Rzycki
- Department of Experimental Physics, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland; (A.K.); (S.K.); (D.D.)
- Correspondence:
| | - Aleksandra Kaczorowska
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland; (A.K.); (S.K.); (D.D.)
| | - Sebastian Kraszewski
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland; (A.K.); (S.K.); (D.D.)
| | - Dominik Drabik
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, 50-370 Wroclaw, Poland; (A.K.); (S.K.); (D.D.)
- Laboratory of Cytobiochemistry, Faculty of Biotechnology, University of Wroclaw, 50-383 Wroclaw, Poland
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