Vivek Kumar Gupta

The dormant phenotype of Mycobacterium tuberculosis that develops during infection poses a major challenge in disease treatment, since these bacilli show tolerance to front-line drugs. An in vitro hypoxia dormancy model was established, which produced phenotypically dormant Mycobacterium smegmatis after prolonged incubation under conditions of low oxygen, low pH, and nutrient limitation. Bacilli in this model displayed the classical dormancy characters, including loss of acid fastness, altered morphology, and, most importantly, tolerance to front-line drugs. The dormant form of M. smegmatis was treated with drugs and phytomolecules. Three phytomolecules exhibited activity against dormant bacilli, as shown by lack of regrowth in solid and liquid media. Further investigation of dormancy-active hits was carried out using in silico approaches to understand the druggable targets of these phytomolecules in dormant bacilli. For this study, molecular docking, molecular dynamics simulations (MDS), and molecular mechanics-generalized born solvent accessibility (MM-GBSA)-based binding energy (ΔG_bind) calculations were performed. Five different targets, namely, isocitrate lyase (ICL), GMP synthase, LuxR, DosR, and serine/threonine protein kinase (STPK), from M. smegmatis and M. tuberculosis were studied in details. DosR and STPK were found to be the common targets in both the species that were more prone to the phytomolecules. The standard DosR inhibitor, HC104A, showed a lower dock score and binding energy of −4.27 and −34.50 kcal/mol, respectively, compared to the natural products under study. The phytomolecule, icariin, showed better docking score (dock score = −5.92 kcal/mol with and binding energy ΔG_bind= −52.96 kcal/mol) with DosR compared to known DosR inhibitor, HC104A (dock score = −4.27 kcal/mol and binding energy ΔG_bind = −34.50 kcal/mol). Similarly, the known STPK inhibitor MRCT67127 showed a lower dock score and binding energy of −4.25 and −29.43 kcal/mol, respectively, compared to the phytomolecule, icariin (dock score = −5.74 kcal/mol and ΔG_bind= −43.41 kcal/mol). These compounds might ultimately lead to new therapeutics or may be useful as adjuvants to the first-line drugs to reduce the lengthy anti-TB therapy in the future.

Genome evolution of Mycobacterium tuberculosis (Mtb) produces new strains resistant to various pre-existing anti-tubercular drugs. Hence, there is an urgent need to explore potent compounds with the most negligible side effects and effective Mtb inhibition. Mtb PyrG (CTP synthase) is a crucial enzyme for the conversion of the uridine triphosphate (UTP) into cytidine triphosphate (CTP) and is essential for the growth of Mtb. Thus, in this study, phytochemicals of Withania somnifera (W. somnifera) were screened to find the potential inhibitors against Mtb PyrG. Molecular docking resulted in the identification of quercetin 3-rutinoside-7-glucoside, rutin, chlorogenic acid and isochlorogenic acid C with a substantial docking score (from −12.6 to −10.8 kcal/mol) contributed by significant intermolecular interactions. Furthermore, 100 ns molecular dynamics simulation, ADME analysis and free binding energy calculations support the stability of docked complexes and drug-likeness for selected compounds, respectively. Collectively, these findings suggest that phytochemicals present in W. somnifera can be considered for further evaluation against Mtb in a series of in vitro and in vivo models. Communicated by Ramaswamy H. Sarma

Background: The widespread hazardous issue of antibiotics resistance can be overcome by the development of target based potent antibacterial agents. Filamentous temperature-sensitive mutant Z (FtsZ), a simpler structural prokaryotic homolog of eukaryotic cytoskeletal tubulin, was considered as a competent target in antibacterial drug discovery. Objective: The purpose of present work is to evaluate the antitubercular activity of virtual hits by funnel-shaped filtering with glide docking followed by MM-GBSA binding energy and molecular dynamics simulation. Pharmacokinetics and biochemical activity of the computationally screened virtual hits have been studied to focus their potential to inhibit the bacterial cell division. Method: The docking study was performed against the crystal structure of Staphylococcus aureus and Mycobacterium tuberculosis FtsZ protein with the hits obtained from High Throughput Virtual Screening using Glide module in Schrodinger. ADME profile and 50 ns molecular dynamics simulationstudies were performed using the Schrödinger suite. The minimal inhibitory concentration of the test compounds were determined bythe colorimetric method by Resazurin Microtiter plate Assay. Results: The binding of hit molecules T5427054 and 6M356S were mainly supported by van der Waals interaction and an electrostatic component of solvation energycomputed by MM-GBSA method. 50 ns MD simulation built stability and dynamic property of the best-docked complex T5427054/2Q1Y. Both the hit molecules displayed antimycobacterial activity with minimal inhibitory concentration 500 μg/mL. Conclusion: In this study, it is found that new screened hit molecules with better theoretical results could be preferred to use as antimycobacterial agents and further their structural modification might be improved antimycobacterial properties of hit molecules.

A novel betacoronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which caused a large disease outbreak in Wuhan, China in December 2019, is currently spreading across world’s many of the countries. Along with binding of the virus spike with the host cell receptor, fusion of the viral envelope with host cell membranes is a critical step in establishing successful infection of SARS-CoV-2. In this entry process, a diversity of host cell proteases and andro-gen receptor play a very important role directly or indirectly. These features of SARS-CoV-2 entry contribute to its rapid spread and severe symptoms, high fatality rates among infected patients. This review is based on latest published literature including review articles, research articles, hypothetical manuscript, pre-print articles and official documents. The literature search was made from various published papers on physiological aspects relevant to SARS-CoV and SARS-CoV-2. In this report, we focus on the role of host cell proteases (ACE2, ADAM17, TMPRSS2) and androgen receptor (AR) in SARS-CoV-2 infection. The hypotheses put forth by us are based on the role played by the proteases ACE2, ADAM17, TMPRSS2 and AR in SARS-CoV-2 infection which were deduced based on various studies. We have also summarized how these host proteins increase the pathology and the infective ability of SARS-CoV-2 and we posit that their inhibition may be a therapeutic option for preventing SARS-CoV-2 infection.

Introduction: This review aimed at providing an update on the application of proteomics-based approaches to gain recent insights of Mycobacterium tuberculosis (M.tb) and its relevance to clinic. Proteomics and bioinformatics approaches helped in the identification and characterization of novel proteins. Studying M.tb, causative agent of tuberculosis (TB), at the proteomic level can contribute to the identification of proteins which can be considered as potential targets for developed drugs and can help us in better understanding the pathogen physiology. Areas covered: In this review we have presented a comprehensive literature pertaining to role of proteomics in understanding M.tb. We have also focused on how the development and advancement in technology in the field of proteomics has augmented the research and played a pivotal role in answering many unexplored questions. Lastly, the application of proteomics to clinic has also been discussed. Expert commentary: We envisage that proteomics has gained remarkable momentum over the years. Proteomics can play an important role in the discovery of biomarkers for TB and other diseases. Also, it can aid in development of effective vaccines and simple, rapid and cost-effective test for the diagnosis of TB which is crucial for the management and control of the disease.