Schiff base clubbed benzothiazole: synthesis, potent antimicrobial and MCF-7 anticancer activity, DNA cleavage and computational study

Abstract

Schiff bases containing benzothiazole unit are synthesized and characterized by 1H NMR, 13C NMR, LC–MS, UV–visible and fluorescence spectroscopy methods. Synthesized compounds were evaluated for in vitro antibacterial activities on four different strains (Staphylococcus aureus, Bacillus sps, Escherichia. coli and Klebsiella pneumoniae) and antifungal activity on one strain (Candida albicans) by using ‘micro-broth dilution method’ (MIC in µg/mL). All compounds showed excellent antibacterial activity for S. aureus, E. coli and K. pneumoniae strains, as well as an antifungal activity for C. albicans, compared to standard Ciprofloxacin and Fluconazole, respectively. Molecular docking studies were carried out to get more insight into the binding mechanism. Reactivity of molecules was assessed using molecular electrostatic potential (MEP). HOMO–LUMO gap, chemical hardness and global softness were calculated and correlated with antimicrobial activity. VS5-e exhibits excellent antimicrobial activities and also shows more chemical reactivity and less toxicity which were confirmed by smaller HOMO–LUMO gap, lesser chemical hardness, higher global softness and lesser electrophilicity index. Henceforth, it was further assessed for DNA cleavage and against MCF-7 breast cancer cell. VS5-e reveals 85.82% inhibition of cancer cells at a concentration of 200 µg/mL. The compound VS5-e showed less toxicity to normal cells at the concentration required to produce an anticancer effect (with high IC50 = 973 µg/mL).Communicated by Ramaswamy H. Sarma