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Novel Schiff bases (SBs) were synthesized by condensation of 2-(1-Amino benzyl) benzimidazole with heterocyclic and aromatic carbonyl compounds. The structural characterization was done using 1H, 13C NMR, FTIR and ES-MS spectroscopic techniques. The in silico pharmacokinetics showed that nearly all compounds obeyed Lipinski rule of 5 with low toxicity and metabolic stability. The global reactivity descriptors were calculated using DFT approach. The molecular docking result of SBs with ct-DNA suggested interaction via groove binding mode. The antibacterial activity was tested against S. aureus and E. coli, indicated significant inhibition than reference drug. The compound 4d gave best results at 50 μg ml−1 concentrations. UV/Vis and Fluorescence spectroscopy tools were used to evaluate ct-DNA binding ability of compounds 4a–e through hypochromic shift. The steady state fluorescence predicted a moderate binding constant of 1.12 × 104 for 4d, indicative of non-intercalative mode.

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Synthesis of Various S-S Linked Symmetric Bisazaheterocycles: a Review -(KHANNA, L.; KHANNA, P.; PANDA, C. S.; PANDA, S. S.; Mini-Rev. Org. Chem. 10 (2013) 3, 268-280, http://dx.

In this study, synthesis of 15 novel bis indole‐based Schiff bases (SBs) 4a–4o was conducted by condensation of 2‐(1‐aminobenzyl)benzimidazole with symmetrical bis‐isatins linked via five alkyl chains (n = 2–6). These were subjected to ADME (absorption, distribution, metabolism and excretion), physiochemical properties, molecular docking, in vitro antibacterial and antioxidant studies. The in silico studies indicated lower toxicity with metabolic stability for nearly all the derivatives proving reliability as drug candidates. The comparative antibacterial study against Staphylococcus aureus and Escherichia coli, also showed a superior inhibition than reference drug and their mono counterparts. The increase in linker alkyl chain length and variation of substituents in indole, further predicted increased inhibition, with maximum value for compound 4o at 50 μg/ml. The in vitro calf thymus DNA (ct‐DNA) binding ability of compounds 4c, 4f, 4i, 4l, 4 m, 4n, and 4o was evaluated via ultraviolet‐visible and fluorescence spectroscopy techniques. A hyperchromic effect was observed with no apparent wavelength shift which predicted for the groove binding mode. A moderate binding constant for 4o, in fluorescence results, confirms groove binding. The molecular docking of 4o with ct‐DNA (PDBID:1BNA) and SARS‐CoV‐2 Mpro (3CL protease, PDBID:6LU7) prove its efficacy as potential DNA binder and antiviral agent.

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Benzimidazole is a heterocyclic moiety of immense importance as it acts as a primary “biolinker” in diverse synthetic routes to obtain bioactive compounds. Substituted benzimidazoles are known to possess a varied range of pharmacological applications, namely, anti‐cancer, anti‐diabetic, anti‐inflammatory, and antiviral like anti‐HIV and anti‐fungal. A number of reviews covering the important aspects of benzimidazoles such as pharmacological activities, SAR studies, and well‐known methods of synthesis have appeared in the literature. However, green synthetic methods particularly using transition metal (TM) catalysts and their nanoparticles, although being more viable and extensively applied by researchers in the present scenario, have not been exclusively and expansively reviewed. Besides this, the vital precursors required for knitting the skeleton of benzimidazole are mainly o‐aryldiamines. The conventional synthesis generally involved the condensation of these diamines with carbonyl/carboxylic acid derivatives either via high temperature heating or via adding strong acids, mostly resulting in poor yields or mixtures. However, recent trends are replacing these conditions by mild and green conditions through TM catalysts. Therefore, the current review emphasizes on the recent trends adopted in the synthesis of benzimidazoles using condensation reaction of o‐phenylenediamines and various aldehydes/ester/amide/alcohols with TM in a catalytic role in nanoform and under environmentally benign green conditions.