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Item Copper-mediated cyclization of thiosemicarbazones leading to 1,3,4-thiadiazoles: Structural elucidation, DFT calculations, in vitro biological evaluation and in silico evaluation studies(Elsevier, 2024-05) Garg, MohitCancer's global impact necessitates innovative and less toxic treatments. Thiosemicarbazones (TSCs), adaptable metal chelators, offer such potential. In this study, we have synthesized N (4)-substituted heterocyclic TSCs from syringaldehyde (TSL1, TSL2), and also report the unexpected copper-mediated cyclization of the TSCs to form thiadiazoles (TSL3, TSL4), expanding research avenues. This work includes extensive characterization and studies such as DNA/protein binding, molecular docking, and theoretical analyses to demonstrate the potential of the as-prepared TSCs and thiadiazoles against different cancer cells. The DFT results depict that the thiadiazoles exhibit greater structural stability and reduced reactivity compared to the corresponding TSCs. The docking results suggest superior EGFR inhibition for TSL3 with a binding constant value of − 6.99 Kcal/mol. According to molecular dynamics studies, the TSL3-EGFR complex exhibits a lower average RMSD (1.39 nm) as compared to the TSL1-EGFR complex (3.29 nm) suggesting that both the thiadiazole and thiosemicarbazone examined here can be good inhibitors of EGFR protein, also that TSL3 can inhibit EGFR better than TSL1. ADME analysis indicates drug-likeness and oral availability of the thiadiazole-based drugs. The DNA binding experiment through absorption and emission spectroscopy discovered that TSL3 is more active towards DNA which is quantitatively calculated with a Kb value of 4.74 × 106 M−1, Kq value of 4.04 × 104 M−1and Kapp value of 5 × 106 M−1. Furthermore, the BSA binding studies carried out with fluorescence spectroscopy showed that TSL3 shows better binding capacity (1.64 × 105 M−1) with BSA protein. All the compounds show significant cytotoxicity against A459-lung, MCF-7-breast, and HepG2-liver cancer cell lines; TSL3 exhibits the best cytotoxicity, albeit less effective than cisplatin. Thiadiazoles demonstrate greater cytotoxicity than the TSCs. Overall, the promise of TSCs and thiadiazoles in cancer research is highlighted by this study. Furthermore, it unveils unexpected copper-mediated cyclization of the TSCs to thiadiazoles.Item In silico evaluation of bisphosphonates identifies leading candidates for SARS-CoV-2 RdRp inhibition(Elsevier, 2025-05) Garg, Mohit; Murugesan, SankaranarayananThe novel coronavirus disease (COVID-19) pandemic has resulted in 777 million confirmed cases and over 7 million deaths worldwide, with insufficient treatment options. Innumerable efforts are being made around the world for faster identification of therapeutic agents to treat the deadly disease. Post Acute Sequelae of SARS-CoV-2 infection or COVID-19 (PASC), also called Long COVID, is still being understood and lacks treatment options as well. A growing list of drugs are being suggested by various in silico, in vitro and ex vivo models, however currently only two treatment options are widely used: the RNA-dependent RNA polymerase (RdRp) inhibitor remdesivir, and the main protease inhibitor nirmatrelvir in combination with ritonavir. Computational drug development tools and in silico studies involving molecular docking, molecular dynamics, entropy calculations and pharmacokinetics can be useful to identify new targets to treat COVID-19 and PASC, as shown in this work and our recent paper that identified alendronate as a promising candidate. In this study, we have investigated all bisphosphonates (BPs) on the ChEMBL database which can bind competitively to nidovirus RdRp-associated nucleotidyl (NiRAN) transferase domain, and systematically down selected seven candidates (CHEMBL608526, CHEMBL196676, CHEMBL164344, CHEMBL4291724, CHEMBL4569308, CHEMBL387132, CHEMBL98211), two of which closely resemble the approved drugs minodronate and zoledronate. This work and our recent paper together provide an in silico mechanistic explanation for alendronate and zoledronate users having dramatically reduced odds of SARS-CoV-2 testing, COVID-19 diagnosis, and COVID-19-related hospitalizations, and indicate that similar observational studies in Japan with minodronate could be valuable.Item Comprehensive analysis of hydrazone Schiff bases: synthesis, structural characterization, DFT studies, molecular docking insights and bioactivity assessment(Elsevier, 2025-07) Garg, MohitThe four new hydrazone Schiff bases have been synthesized in absolute ethanol at the reflux of 78 °C. These hydrazones are named as: (E)-1-(2,4-dinitrophenyl)-2-(2-ethoxy benzylidene) hydrazine(2-EDNPH) (L1), (E)-1-(2,4-dinitrophenyl)-2-(4-ethoxy benzylidene) hydrazine(4-EDNPH) (L2), (E)-3-chloro-2-((2-(2,4-dinitrophenyl) hydrazinylidene) methyl) phenol(3-Cl-2-OH-DNPH) (L3) and (E)-1-(2,4-dinitrophenyl)-2-(thiophen-3-ylmethylene) hydrazine (3-Thiophene Carbaldehyde-DNPH) (L4). Spectroscopic and physicochemical techniques were employed to validate these compound's structure, including 1H NMR, 13C NMR spectra, UV–Vis, IR, and melting point. A solubility test is also carried out on all the Schiff bases, indicating that all four ligands are soluble in THF and DMF. The thermal breakdown behavior of all ligands is being examined by thermogravimetric analysis (TGA/DTG) at a heating rate of 10 °C min−1 under a nitrogen environment. The crystalline structure of L1 was also investigated in an XtaLAB AFC12 (RINC): Kappa single diffractometer, which included unit cell computation and data collecting. The radioactive photon was created with MoKα (λ = 0.7107Å). In addition, density functional theory (DFT) is utilized to compute the optimized molecular structures, stability, reactivity, and numerous chemical characteristics of the synthesized ligands. The in-silico prediction of ADME features revealed that synthesized compounds gain notable drug-like characteristics. Also, molecular docking was enforced to predict the inhibitory action of the β-ketoacyl acyl carrier (KAS1) protein of E. Coli (PDB Id: 6TZF) on the examined hydrazones. Finally, all ligands were to assess the anti-bacterial properties against gram-positive (B. subtilis and MRSA) and gram-negative (P. mirabilis and E. coli) infections; only L1 and L2 showed activity against these pathogens.Item In silico anti-viral assessment of phytoconstituents in a traditional (Siddha Medicine) polyherbal formulation – Targeting Mpro and pan-coronavirus post-fusion Spike protein(Elsevier, 2023-07) Murugesan, Sankaranarayanan; Deepa, P. R.; Garg, MohitNovel nature of the viral pathogen SARS-CoV-2 and the absence of standard drugs for treatment, have been a major challenge to combat this deadly infection. Natural products offer safe and effective remedy, for which traditional ethnic medicine can provide leads. An indigenous poly-herbal formulation, Kabasura Kudineer from Siddha system of medicine was evaluated here using a combination of computational approaches, to identify potential inhibitors against two anti-SARS-CoV-2 targets – post-fusion Spike protein (structural protein) and main protease (Mpro, non-structural protein).