Synthesis, spectral characterization, antimicrobial, DNA interactions and molecular modeling studies of metal complexes of 1, 3-benzothiazole carbohydrazone

Abstract

The compound N $$^\prime $$ -[(Z)-furan-2-ylmethylidene]-1,3-benzothiazole-2-carbohydrazone (FMBC) and its Cu (II), Ni (II) and Zn (II) complexes were synthesized and characterized by Mass, FT-IR, NMR, elemental analysis, TGA, ESR and SEM-EDX. Based on spectro-analytical data, geometries have been assigned to the metal complexes in which the FMBC acted as bidentate chelate in its mono dissociated form (pKa = 10.56). HyperChem 7.5 software was used for quantum chemical calculations using semi-empirical method. The eigenvalues of frontier orbitals and their corresponding contour maps of HOMO and LUMO for the title compound were computed by means of single point PM3 method. DNA binding of the synthesized complexes with calf thymus DNA was studied by spectrophotometry, fluorescence and viscosity techniques. From the experimental results, it is found that the complexes bind effectively to CT-DNA through an intercalative mode. Molecular docking studies with host DNA moiety inferred corroborative results for binding affinity of the compounds in accordance with experimental data. $$\hbox {IC}_{50}$$ values calculated from the cytotoxicity studies carried out on HeLa cell line by MTT assay inferred obviously enhanced activity of the metal complexes over unbound free ligand. The candidate compounds screened for antimicrobial activity against bacterial species Bacillus, Escherichia coli, Staphylococcus, Pseudomonas and fungal species Sclerotium rolfsii and Macrophomina phaseolina signified greater potency of metal complexes over free carbohydrazone ligand. SYNOPSIS N $$^\prime $$ -[(Z)-furan-2-ylmethylidene]-1,3-benzothiazole-2-carbohydrazone (FMBC) and its Cu(II), Ni(II) and Zn(II) complexes were synthesized and characterized by various spectro-analytical techniques. From the DNA binding studies, it is found that the complexes bind effectively to CT-DNA through an intercalative mode.