Identification of potential inhibitor against CTX-M-3 and CTX-M-15 proteins: an in silico and in vitro study.

Extended-spectrum beta-lactamase (ESBL) producing Enterobacteriaceae infection is a serious global threat. ESBLs target 3rd generation cephalosporin antibiotics, the most commonly prescribed medicine for gram-negative bacterial infections. As bacteria are prone to develop resistance against market-available ESBL inhibitors, finding a novel and effective inhibitor has become mandatory. Among ESBL, the worldwide reported two enzymes, CTX-M-15 and CTX-M-3, are selected for the present study. CTX-M-3 protein was modeled, and two thousand phyto-compounds were virtually screened against both proteins. After filtering through docking and pharmacokinetic properties, four phyto-compounds (catechin gallate, silibinin, luteolin, uvaol) were further selected for intermolecular contact analysis and molecular dynamics (MD) simulation. MD trajectory analysis results were compared, revealing that both catechin gallate and silibinin had a stabilizing effect against both proteins. Silibinin having the lowest docking score, also displayed the lowest MIC (128 µg/mL) against the bacterial strains. Silibinin was also reported to have synergistic activity with cefotaxime and proved to have bactericidal effect. Nitrocefin assay confirmed that silibinin could inhibit beta-lactamase enzyme only in living cells, unlike clavulanic acid. Thus the present study validated the CTX-M inhibitory activity of silibinin both in silico and in vitro and suggested its promotion for further studies as a potential lead. The present study adopted a protocol through the culmination of bioinformatics and microbiological analyses, which will help future researchers identify more potential leads and design new effective drugs.Communicated by Ramaswamy H. Sarma.

Discovery of phyto-compounds as novel inhibitors against NDM-1 and VIM-1 protein through virtual screening and molecular modelling.

Amid the rise of multi-drug resistance among bacterial pathogens, the drying of the development pipeline of new antibiotics is worrisome. In search of new effective alternatives, phytocompounds can be considered a good one because of their immense antimicrobial property, low toxicity and huge structural diversity. In the present study, 200 phytocompounds were targeted against two Metallo ß-lactamase (MBL) enzymes (NDM-1 and VIM-1) through molecular docking and meropenem was used as a reference drug. The phytocompounds with docking score ≤-8.0 kcal/mol were screened for their pharmacokinetic properties. The three best selected phytocompounds are Coriandrinonediol, Oleanderolide and Uzarigenin. Molecular docking helps to understand binding affinity. The selected phytocompounds showed better result than meropenem. Molecular interaction study reveals their competitive mechanism of inhibition against the target proteins. Coriandrinonediol has docking score -8.3 kcal/mol (NDM-1) and -8.9 kcal/mol (VIM-1), and oleanderolide has docking score -8.2 kcal/mol (NDM-1) and -9.3 kcal/mol (VIM-1). Uzarigenin has the highest binding affinity (-10.4 kcal/mol) among the three against VIM-1 and the lowest binding affinity (-8.1 kcal/mol) against NDM-1. Molecular dynamic (MD) simulation study also supports the stability and flexibility of the above phytocompounds during the MD run. Among the abovementioned three phytocompounds, oleanderolide has given the best result against both target proteins. These phytocompounds are first time reported as MBL inhibitors and their promising in silico results encourage to promote them for further investigation for in vitro and in vivo clinical trials.Communicated by Ramaswamy H. Sarma.

Identification of phytocompounds as newer antiviral drugs against COVID-19 through molecular docking and simulation based study.

COVID-19 pandemic has emerged as a global threat with its highly contagious and mutating nature. Several existing antiviral drugs has been worked on, without proper results and meanwhile the virus is mutating rapidly to create more infectious variant. In order to find some alternatives, phytocompounds can be opted as good one. In this study, three hundred phytocompounds were screened virtually against two viral proteins namely main protease and spike protein. Molecular docking and dynamic simulation study was used to find binding affinity, structural stability and flexibility of the complex. Pharmacokinetic properties were studied through ADMET analysis. To understand energy variation of the complex structure free energy landscape analysis was performed. Among three hundred phytocompounds virtual screening, three phytocompounds were selected for detailed molecular interaction analysis. Oleanderolide, Proceragenin A and Balsaminone A, showed strong binding affinity against both the target proteins and reflected conformational stability throughout the MD run. Oleanderolide, proceragenin A and balsaminone A has docking score -9.4 kcal/mol, -8.6 kcal/mol, and -8.1 kcal/mol respectively against main protease and same -8.3 kcal/mol docking score against spike protein. These three phytocompounds has high gastrointestinal absorption capacity. They were unexplored till now for their antiviral activity. Their promising in silico results suggests that they can be promoted in the long run for development of new antiviral drugs.

Prevalence and molecular characterization of ß-lactamase producers and fluoroquinolone resistant clinical isolates from North East India.

INTRODUCTION: The rapid emergence and variations of antibiotic resistance among common gram negative bacteria cause a significant concern specially in India and all over the world because of high mortality and morbidity rates. METHODS: In our study, we screened 189 bacterial isolates from Assam Medical College & Hospital, Dibrugarh for antibiotic resistance pattern and tried to identify the resistant genes causing responsible for ß-lactam and fluoroquinolones resistance. RESULTS: More than 80% and 45% strains were resistant to all the 3rd generation cephalosporins, fluoroquinolones respectively. Among the 3rd generation cephalosporin resistant strains, 38% and 24% isolates were only ESBL and MBL producers respectively and 11% were reported to have both ESBL and MBL genes. The ESBL positive isolates have shown the dominance of CTX-M3 gene. VIM-1 gene was mostly reported in MBL producers. Our study probably for the first time reporting SIM-1 and SPM-1 MBL gene from India. Mutations in QRDR is found to be the primary cause of fluoroquinolone resistance along with efflux pump and PMQR presence. CONCLUSION: The study represents the first detailed study on antibiotic resistance from NE India this could help to take control measures for the emerging antibiotic resistance in hospital and community based infections in North East India.