Synthesis, spectral characterization, DNA/BSA binding, antimicrobial and in vitro cytotoxicity of cobalt(III) complexes containing 7-hydroxy-4-oxo-4H-chromene Schiff bases

Abstract

The present work deals with the synthesis and characterization of four Co(III) complexes derived from 7-hydroxy-4-oxo-4H-chromene-3-carbaldehyde-4(N)-substituted thiosemicarbazones. Structural confirmation of the complexes 2 and 3 were aided by X-ray crystallographic analysis, which revealed the coordination of azomethine nitrogen, ring carbonyl oxygen and thiol sulfur atoms of the ligands. DNA and Bovine serum albumin (BSA) binding studies brought about the binding ability of the complexes to biomolecules. The binding constant values calculated for the complexes were in the range (0.30–1.19) × 106 M−1 and the mode of interaction was found to be partially intercalative. The mechanism of quenching with BSA was static with quenching constants in the order 1012 M−1s−1. Their antimicrobial profile has been established by testing against four pathogenic bacterial and fungal species. The cytotoxic potential of the complexes were examined against MCF-7 and A549 cells by MTT assay. The IC50 values of the complexes were less than cisplatin, which indicated their greater activity over the standard drug. In addition, testing on human normal keratinocyte cells HaCaT indicated their non toxic nature. Lactate dehydrogenase (LDH) and Nitric oxide (NO) release assays supported the cytotoxic ability and suggested apoptotic mode of cell death induced by the complexes.