Schiff bases based on thio/carbohydrazide: Synthesis, spectroscopic characterization, DFT, antimicrobial, DNA interactions and cytotoxicity studies

Abstract

New Schiff bases (1–8) have been prepared from numerous aldehydes and thio/carbohydrazide. The chemical structures of these compounds were characterized using IR, 1H NMR, 13C NMR spectroscopic methods, and elemental analysis. Electronic and spectroscopic properties of the compounds were determined by DFT calculations performed at the B3LYP/6–311++G(2d,2p) level of theory and were analyzed comparatively with experimental findings. The relationship between some global reactivity parameters and the nucleophilic-electrophilic attack abilities of the compounds and their antimicrobial and cytotoxic activities was also investigated. The antimicrobial effects of the synthesized compounds on microorganisms were screened using disc diffusion methods. According to the disc diffusion results, compound 8 in particular exhibits a high antibacterial potential against Bacillus cereus (15.66 ± 0.57 mm). The interaction of synthesized compounds with pUC18 plasmid DNA was analyzed by the agarose gel electrophoresis method. The results showed that compounds 6, 7, and 8 interact with plasmid DNA and cause fragmentation of the Form I structure. In addition, in vitro, the cytotoxic activity of compounds on HT-29 (human adenocarcinoma colon) cell lines was investigated by the MTT method. Our study showed that compounds 7 and 8 have cytotoxic effects on HT-29 cell lines. The IC50 value was determined to be 96.93 µM for compound 7 and 91.55 µM for compound 8.