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Shafique I, Rafiq M, Rana NF, Menaa F, Almalki F, Aljuaid A, Alnasser SM, Alotaibi AS, Masood MBE, Tanweer T. Computational evaluation of efflux pump homologues and lignans as potent inhibitors against multidrug-resistant Salmonella typhi. PLoS One 2024; 19:e0303285. [PMID: 38917154 PMCID: PMC11198855 DOI: 10.1371/journal.pone.0303285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 04/22/2024] [Indexed: 06/27/2024] Open
Abstract
Typhoid fever, caused by Salmonella enterica serovar typhi, presents a substantial global health threat, particularly in regions with limited healthcare infrastructure. The rise of multidrug-resistant strains of S. typhi exacerbates this challenge, severely compromising conventional treatment efficacy due to over activity of efflux pumps. In our study, a comprehensive exploration of two fundamental aspects to combat MDR in S. typhi is carried out; i.e. employing advanced bioinformatics analyses and AlphaFold AI, We successfully identified and characterised a putative homologue, ABC-TPA, reminiscent of the P-glycoprotein (P-gp) known for its role in multidrug resistance in diverse pathogens. This discovery provides a critical foundation for understanding the potential mechanisms driving antibiotic resistance in S. typhi. Furthermore, employing computational methodologies, We meticulously assessed the potential of lignans, specifically Schisandrin A, B, and C, as promising Efflux Pump Inhibitors (EPIs) against the identified P-gp homologue in S. typhi. Noteworthy findings revealed robust binding interactions of Schisandrin A and B with the target protein, indicating substantial inhibitory capabilities. In contrast, Schisandrin C exhibited instability, showing varied effectiveness among the evaluated lignans. Pharmacokinetics and toxicity predictions underscored the favourable attributes of Schisandrin A, including prolonged action duration. Furthermore, high systemic stability and demanished toxicity profile of SA and SB present their therapeutic efficacy against MDR. This comprehensive investigation not only elucidates potential therapeutic strategies against MDR strains of S. typhi but also highlights the relevance of computational approaches in identifying and evaluating promising candidates. These findings lay a robust foundation for future empirical studies to address the formidable challenges antibiotic resistance poses in this clinically significant infectious diseases.
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Affiliation(s)
- Iqra Shafique
- Department of Biomedical Engineering and Sciences, School of Mechanical & Manufacturing Engineering, National University of Science & Technology, Islamabad, Pakistan
| | - Mehak Rafiq
- School of Interdisciplinary Engineering & Sciences (SINES), National University of Science & Technology, Islamabad, Pakistan
| | - Nosheen Fatima Rana
- Department of Biomedical Engineering and Sciences, School of Mechanical & Manufacturing Engineering, National University of Science & Technology, Islamabad, Pakistan
| | - Farid Menaa
- Department of Medicine and Nanomedicine, California Innovations Corporation, San Diego, CA, United States of America
| | - Fatemah Almalki
- Department of Biology, College of Science and Humanities, Shaqra University, Al Quwaiiyah, Saudi Arabia
| | - Alya Aljuaid
- Department of Biology, College of Science and Humanities, Shaqra University, Al Quwaiiyah, Saudi Arabia
| | | | - Amenah S. Alotaibi
- Department of Biology, Genomic & Biotechnology Unit, Faculty of Science, University of Tabuk, Tabuk, Saudi Arabia
| | - Madahiah Bint E. Masood
- School of Interdisciplinary Engineering & Sciences (SINES), National University of Science & Technology, Islamabad, Pakistan
| | - Tahreem Tanweer
- Department of Biomedical Engineering and Sciences, School of Mechanical & Manufacturing Engineering, National University of Science & Technology, Islamabad, Pakistan
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Singh CK, Sodhi KK, Shree P, Nitin V. Heavy Metals as Catalysts in the Evolution of Antimicrobial Resistance and the Mechanisms Underpinning Co-selection. Curr Microbiol 2024; 81:148. [PMID: 38642082 DOI: 10.1007/s00284-024-03648-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 02/22/2024] [Indexed: 04/22/2024]
Abstract
The menace caused by antibiotic resistance in bacteria is acknowledged on a global scale. Concerns over the same are increasing because of the selection pressure exerted by a huge number of different antimicrobial agents, including heavy metals. Heavy metals are non-metabolizable and recalcitrant to degradation, therefore the bacteria can expel the pollutants out of the system and make it less harmful via different mechanisms. The selection of antibiotic-resistant bacteria may be influenced by heavy metals present in environmental reservoirs. Through co-resistance and cross-resistance processes, the presence of heavy metals in the environment can act as co-selecting agents, hence increasing resistance to both heavy metals and antibiotics. The horizontal gene transfer or mutation assists in the selection of mutant bacteria resistant to the polluted environment. Hence, bioremediation and biodegradation are sustainable methods for the natural clean-up of pollutants. This review sheds light on the occurrence of metal and antibiotic resistance in the environment via the co-resistance and cross-resistance mechanisms underpinning co-selection emphasizing the dearth of studies that specifically examine the method of co-selection in clinical settings. Furthermore, it is advised that future research incorporate both culture- and molecular-based methodologies to further our comprehension of the mechanisms underlying bacterial co- and cross-resistance to antibiotics and heavy metals.
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Affiliation(s)
| | - Kushneet Kaur Sodhi
- Department of Zoology, Sri Guru Tegh Bahadur Khalsa College, University of Delhi, Delhi, 110007, India.
| | - Pallee Shree
- Department of Zoology, Lady Irwin College, University of Delhi, Delhi, 110001, India
| | - V Nitin
- Bhaskaracharya College of Applied Sciences, University of Delhi, Delhi, 110075, India
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Rzymski P, Gwenzi W, Poniedziałek B, Mangul S, Fal A. Climate warming, environmental degradation and pollution as drivers of antibiotic resistance. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 346:123649. [PMID: 38402936 DOI: 10.1016/j.envpol.2024.123649] [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: 10/17/2023] [Revised: 02/17/2024] [Accepted: 02/22/2024] [Indexed: 02/27/2024]
Abstract
Antibiotic resistance is a major challenge to public health, but human-caused environmental changes have not been widely recognized as its drivers. Here, we provide a comprehensive overview of the relationships between environmental degradation and antibiotic resistance, demonstrating that the former can potentially fuel the latter with significant public health outcomes. We describe that (i) global warming favors horizontal gene transfer, bacterial infections, the spread of drug-resistant pathogens due to water scarcity, and the release of resistance genes with wastewater; (ii) pesticide and metal pollution act as co-selectors of antibiotic resistance mechanisms; (iii) microplastics create conditions promoting and spreading antibiotic resistance and resistant bacteria; (iv) changes in land use, deforestation, and environmental pollution reduce microbial diversity, a natural barrier to antibiotic resistance spread. We argue that management of antibiotic resistance must integrate environmental goals, including mitigation of further increases in the Earth's surface temperature, better qualitative and quantitative protection of water resources, strengthening of sewage infrastructure and improving wastewater treatment, counteracting the microbial diversity loss, reduction of pesticide and metal emissions, and plastic use, and improving waste recycling. These actions should be accompanied by restricting antibiotic use only to clinically justified situations, developing novel treatments, and promoting prophylaxis. It is pivotal for health authorities and the medical community to adopt the protection of environmental quality as a part of public health measures, also in the context of antibiotic resistance management.
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Affiliation(s)
- Piotr Rzymski
- Department of Environmental Medicine, Poznan University of Medical Sciences, Poznań, Poland.
| | - Willis Gwenzi
- Biosystems and Environmental Engineering Research Group, 380 New Adylin, Marlborough, Harare, Zimbabwe; Alexander von Humboldt Fellow and Guest Professor, Grassland Science and Renewable Plant Resources, Faculty of Organic Agricultural Sciences, Universität Kassel, Witzenhausen, Germany; Alexander von Humboldt Fellow and Guest Professor, Leibniz Institute for Agricultural Engineering and Bioeconomy, Potsdam, Germany
| | - Barbara Poniedziałek
- Department of Environmental Medicine, Poznan University of Medical Sciences, Poznań, Poland
| | - Serghei Mangul
- Titus Family Department of Clinical Pharmacy, USC Alfred E. Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA, USA
| | - Andrzej Fal
- Department of Allergy, Lung Diseases and Internal Medicine Central Clinical Hospital, Ministry of Interior, Warsaw, Poland; Collegium Medicum, Warsaw Faculty of Medicine, Cardinal Stefan Wyszyński University, Warsaw, Poland
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Pun M, Khazanov N, Galsurker O, Kerem Z, Senderowitz H, Yedidia I. Inhibition of AcrAB-TolC enhances antimicrobial activity of phytochemicals in Pectobacterium brasiliense. FRONTIERS IN PLANT SCIENCE 2023; 14:1161702. [PMID: 37229130 PMCID: PMC10203483 DOI: 10.3389/fpls.2023.1161702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 04/19/2023] [Indexed: 05/27/2023]
Abstract
Introduction The eons-long co-evolvement of plants and bacteria led to a plethora of interactions between the two kingdoms, in which bacterial pathogenicity is counteracted by plant-derived antimicrobial defense molecules. In return, efflux pumps (EP) form part of the resistance mechanism employed by bacteria to permit their survival in this hostile chemical environment. In this work we study the effect of combinations of efflux pump inhibitors (EPIs) and plant-derived phytochemicals on bacterial activity using Pectobacteriun brasiliense 1692 (Pb1692) as a model system. Methods We measured the minimal inhibitory concentration (MIC) of two phytochemicals, phloretin (Pht) and naringenin (Nar), and of one common antibiotic ciprofloxacin (Cip), either alone or in combinations with two known inhibitors of the AcrB EP of Escherichia coli, a close homolog of the AcrAB-TolC EP of Pb1692. In addition, we also measured the expression of genes encoding for the EP, under similar conditions. Results Using the FICI equation, we observed synergism between the EPIs and the phytochemicals, but not between the EPIs and the antibiotic, suggesting that EP inhibition potentiated the antimicrobial activity of the plant derived compounds, but not of Cip. Docking simulations were successfully used to rationalize these experimental results. Discussion Our findings suggest that AcrAB-TolC plays an important role in survival and fitness of Pb1692 in the plant environment and that its inhibition is a viable strategy for controlling bacterial pathogenicity.
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Affiliation(s)
- Manoj Pun
- The Institute of Plant Sciences, Volcani Center, Agricultural Research Organization (ARO), Rishon Lezion, Israel
- The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Netaly Khazanov
- Department of Chemistry, Bar-Ilan University, Ramat Gan, Israel
| | - Ortal Galsurker
- The Institute of Plant Sciences, Volcani Center, Agricultural Research Organization (ARO), Rishon Lezion, Israel
| | - Zohar Kerem
- The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | | | - Iris Yedidia
- The Institute of Plant Sciences, Volcani Center, Agricultural Research Organization (ARO), Rishon Lezion, Israel
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Vij S, Thakur R, Rishi P. Reverse engineering approach: a step towards a new era of vaccinology with special reference to Salmonella. Expert Rev Vaccines 2022; 21:1763-1785. [PMID: 36408592 DOI: 10.1080/14760584.2022.2148661] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
INTRODUCTION Salmonella is responsible for causing enteric fever, septicemia, and gastroenteritis in humans. Due to high disease burden and emergence of multi- and extensively drug-resistant Salmonella strains, it is becoming difficult to treat the infection with existing battery of antibiotics as we are not able to discover newer antibiotics at the same pace at which the pathogens are acquiring resistance. Though vaccines against Salmonella are available commercially, they have limited efficacy. Advancements in genome sequencing technologies and immunoinformatics approaches have solved the problem significantly by giving rise to a new era of vaccine designing, i.e. 'Reverse engineering.' Reverse engineering/vaccinology has expedited the vaccine identification process. Using this approach, multiple potential proteins/epitopes can be identified and constructed as a single entity to tackle enteric fever. AREAS COVERED This review provides details of reverse engineering approach and discusses various protein and epitope-based vaccine candidates identified using this approach against typhoidal Salmonella. EXPERT OPINION Reverse engineering approach holds great promise for developing strategies to tackle the pathogen(s) by overcoming the limitations posed by existing vaccines. Progressive advancements in the arena of reverse vaccinology, structural biology, and systems biology combined with an improved understanding of host-pathogen interactions are essential components to design new-generation vaccines.
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Affiliation(s)
- Shania Vij
- Department of Microbiology, Panjab University, Chandigarh, India
| | - Reena Thakur
- Department of Microbiology, Panjab University, Chandigarh, India
| | - Praveen Rishi
- Department of Microbiology, Panjab University, Chandigarh, India
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Ramamurthy T, Ghosh A, Chowdhury G, Mukhopadhyay AK, Dutta S, Miyoshi SI. Deciphering the genetic network and programmed regulation of antimicrobial resistance in bacterial pathogens. Front Cell Infect Microbiol 2022; 12:952491. [PMID: 36506027 PMCID: PMC9727169 DOI: 10.3389/fcimb.2022.952491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 10/25/2022] [Indexed: 11/24/2022] Open
Abstract
Antimicrobial resistance (AMR) in bacteria is an important global health problem affecting humans, animals, and the environment. AMR is considered as one of the major components in the "global one health". Misuse/overuse of antibiotics in any one of the segments can impact the integrity of the others. In the presence of antibiotic selective pressure, bacteria tend to develop several defense mechanisms, which include structural changes of the bacterial outer membrane, enzymatic processes, gene upregulation, mutations, adaptive resistance, and biofilm formation. Several components of mobile genetic elements (MGEs) play an important role in the dissemination of AMR. Each one of these components has a specific function that lasts long, irrespective of any antibiotic pressure. Integrative and conjugative elements (ICEs), insertion sequence elements (ISs), and transposons carry the antimicrobial resistance genes (ARGs) on different genetic backbones. Successful transfer of ARGs depends on the class of plasmids, regulons, ISs proximity, and type of recombination systems. Additionally, phage-bacterial networks play a major role in the transmission of ARGs, especially in bacteria from the environment and foods of animal origin. Several other functional attributes of bacteria also get successfully modified to acquire ARGs. These include efflux pumps, toxin-antitoxin systems, regulatory small RNAs, guanosine pentaphosphate signaling, quorum sensing, two-component system, and clustered regularly interspaced short palindromic repeats (CRISPR) systems. The metabolic and virulence state of bacteria is also associated with a range of genetic and phenotypic resistance mechanisms. In spite of the availability of a considerable information on AMR, the network associations between selection pressures and several of the components mentioned above are poorly understood. Understanding how a pathogen resists and regulates the ARGs in response to antimicrobials can help in controlling the development of resistance. Here, we provide an overview of the importance of genetic network and regulation of AMR in bacterial pathogens.
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Affiliation(s)
- Thandavarayan Ramamurthy
- Division of Bacteriology, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, India,*Correspondence: Thandavarayan Ramamurthy,
| | - Amit Ghosh
- Division of Bacteriology, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Goutam Chowdhury
- Division of Bacteriology, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Asish K. Mukhopadhyay
- Division of Bacteriology, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Shanta Dutta
- Division of Bacteriology, ICMR-National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Shin-inchi Miyoshi
- Collaborative Research Centre of Okayama University for Infectious Diseases at ICMR- National Institute of Cholera and Enteric Diseases, Kolkata, India,Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
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Shi X, Xia Y, Wei W, Ni BJ. Accelerated spread of antibiotic resistance genes (ARGs) induced by non-antibiotic conditions: Roles and mechanisms. WATER RESEARCH 2022; 224:119060. [PMID: 36096030 DOI: 10.1016/j.watres.2022.119060] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 08/28/2022] [Accepted: 09/04/2022] [Indexed: 05/28/2023]
Abstract
The global spread of antibiotic resistance genes (ARGs) has wreaked havoc with the treatment efficiency of antibiotics and, ultimately, anti-microbial chemotherapy, and has been conventionally attributed to the abuse and misuse of antibiotics. However, the ancient ARGs have alterative functions in bacterial physiology and thus they could be co-regulated by non-antibiotic conditions. Recent research has demonstrated that many non-antibiotic chemicals such as microplastics, metallic nanoparticles and non-antibiotic drugs, as well as some non-antibiotic conditions, can accelerate the dissemination of ARGs. These results suggested that the role of antibiotics might have been previously overestimated whereas the effects of non-antibiotic conditions were possibly ignored. Thus, in an attempt to fully understand the fate and behavior of ARGs in the eco-system, it is urgent to critically highlight the role and mechanisms of non-antibiotic chemicals and related environmental factors in the spread of ARGs. To this end, this timely review assessed the evolution of ARGs, especially its function alteration, summarized the non-antibiotic chemicals promoting the spread of ARGs, evaluated the non-antibiotic conditions related to ARG dissemination and analyzed the molecular mechanisms related to spread of ARGs induced by the non-antibiotic factors. Finally, this review then provided several critical perspectives for future research.
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Affiliation(s)
- Xingdong Shi
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Yu Xia
- School of Environmental Science and Engineering, College of Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Wei Wei
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Bing-Jie Ni
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW 2007, Australia.
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Wesseling CJ, Martin NI. Synergy by Perturbing the Gram-Negative Outer Membrane: Opening the Door for Gram-Positive Specific Antibiotics. ACS Infect Dis 2022; 8:1731-1757. [PMID: 35946799 PMCID: PMC9469101 DOI: 10.1021/acsinfecdis.2c00193] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
New approaches to target antibacterial agents toward Gram-negative bacteria are key, given the rise of antibiotic resistance. Since the discovery of polymyxin B nonapeptide as a potent Gram-negative outer membrane (OM)-permeabilizing synergist in the early 1980s, a vast amount of literature on such synergists has been published. This Review addresses a range of peptide-based and small organic compounds that disrupt the OM to elicit a synergistic effect with antibiotics that are otherwise inactive toward Gram-negative bacteria, with synergy defined as a fractional inhibitory concentration index (FICI) of <0.5. Another requirement for the inclusion of the synergists here covered is their potentiation of a specific set of clinically used antibiotics: erythromycin, rifampicin, novobiocin, or vancomycin. In addition, we have focused on those synergists with reported activity against Gram-negative members of the ESKAPE family of pathogens namely, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and/or Acinetobacter baumannii. In cases where the FICI values were not directly reported in the primary literature but could be calculated from the published data, we have done so, allowing for more direct comparison of potency with other synergists. We also address the hemolytic activity of the various OM-disrupting synergists reported in the literature, an effect that is often downplayed but is of key importance in assessing the selectivity of such compounds for Gram-negative bacteria.
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Vats P, Kaur UJ, Rishi P. Heavy metal-induced selection and proliferation of antibiotic resistance: A review. J Appl Microbiol 2022; 132:4058-4076. [PMID: 35170159 DOI: 10.1111/jam.15492] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 12/28/2021] [Accepted: 02/11/2022] [Indexed: 11/28/2022]
Abstract
Antibiotic resistance is recognized as a global threat to public health. The selection and evolution of antibiotic resistance in clinical pathogens was believed to be majorly driven by the imprudent use of antibiotics. However, concerns regarding the same, through selection pressure by a multitude of other antimicrobial agents, such as heavy metals, are also growing. Heavy metal contamination co-selects antibiotic and metal resistance through numerous mechanisms, such as co-resistance and cross-resistance. Here, we have reviewed the role of heavy metals as antimicrobial resistance driving agents and the underlying concept and mechanisms of co-selection, while also highlighting the scarcity in studies explicitly inspecting the process of co-selection in clinical settings. Prospective strategies to manage heavy metal-induced antibiotic resistance have also been deliberated, underlining the need to find specific inhibitors so that alternate medicinal combinations can be added to the existing therapeutic armamentarium.
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Affiliation(s)
- Prakriti Vats
- Department of Microbiology, Panjab University, Chandigarh, India
| | - Ujjwal Jit Kaur
- Department of Microbiology, Panjab University, Chandigarh, India
| | - Praveen Rishi
- Department of Microbiology, Panjab University, Chandigarh, India
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Mehta J, Rolta R, Dev K. Role of medicinal plants from North Western Himalayas as an efflux pump inhibitor against MDR AcrAB-TolC Salmonella enterica serovar typhimurium: In vitro and In silico studies. JOURNAL OF ETHNOPHARMACOLOGY 2022; 282:114589. [PMID: 34492321 DOI: 10.1016/j.jep.2021.114589] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 08/20/2021] [Accepted: 08/29/2021] [Indexed: 06/13/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Zingiber officinale Roscoe has been utilized traditionally to cure various diseases like cold, cough, diarrhoea, nausea, asthma, vomiting, toothache, stomach upset, respiratory disorders, joint pain, and throat infection. It is also consumed as spices and ginger tea. AIM OF THE STUDY The current study was aimed to identify the phytocompounds of traditional medicinal plants of North-Western Himalaya that could inhibit the AcrAB-TolC efflux pump activity of Salmonella typhimurium and become sensitive to antibiotic killing at reduced dosage. MATERIAL AND METHODS Medicinal plant extracts were prepared using methanol, aqueous, and ethyl acetate and tested for efflux pump inhibitory activity of Salmonella typhimurium NKS70, NKS174, and NKS773 strains using Ethidium Bromide (EtBr)-agar cartwheel assay. Synergism was assessed by the agar well diffusion method and EPI activity by berberine uptake and EtBr efflux inhibition assays. Microdilution method and checkerboard assays were done to determine the minimum inhibitory concentration (MIC) and fractional inhibitory concentration index (FICI) respectively for a bioactive compound. To validate the phytocompound and efflux pump interaction, molecular docking with 6IE8 (RamA) and 6IE9 (RamR) targets was done using autoDock vina software. Toxicity prediction and drug-likeness were predicted by using ProTox-II and Molinspiration respectively. RESULTS Methanolic and ethyl acetate extracts of P. integerrima, O. sanctum, C. asiatica, M. charantia, Z. officinale, and W. somnifera in combination with ciprofloxacin and tetracycline showed synergistic antimicrobial activity with GIIs of 0.61-1.32 and GIIs 0.56-1.35 respectively. Methanolic extract of Z. officinal enhanced the antimicrobial potency of berberine (2 to 4-folds) and increased the EtBr accumulation. Furthermore, bioassay-guided fractionation leads to the identification of lariciresinol in ethyl acetate fraction, which decreased the MIC by 2-to 4-folds. The ΣFIC values varied from 0.30 to 0.55 with tetracycline, that indicated synergistic/additive effects. Lariciresinol also showed a good binding affinity with 6IE8 (-7.4 kcal mol-1) and 6IE9 (-8.2 kcal mol-1), which is comparable to tetracycline and chenodeoxycholic acid. Lariciresinol followed Lipinski's rule of five. CONCLUSION The data suggest that lariciresinol from Z. officinale could be a potential efflux pump inhibitor that could lead to effective killing of drug resistant Salmonella typhimurium at lower MIC. Molecular docking confirmed the antibacterial EPI mechanism of lariciresinol in Salmonella typhimurium and confirmed to be safe for future use.
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Affiliation(s)
- Jyoti Mehta
- Faculty of Applied Sciences and Biotechnology, Shoolini University of Biotechnology and Management Sciences, Bajhol, PO Sultanpur, District Solan, 173229, Himachal Pradesh, India.
| | - Rajan Rolta
- Faculty of Applied Sciences and Biotechnology, Shoolini University of Biotechnology and Management Sciences, Bajhol, PO Sultanpur, District Solan, 173229, Himachal Pradesh, India
| | - Kamal Dev
- Faculty of Applied Sciences and Biotechnology, Shoolini University of Biotechnology and Management Sciences, Bajhol, PO Sultanpur, District Solan, 173229, Himachal Pradesh, India.
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