Synthesis, spectral characterization, molecular docking studies, biological activity of (E)-2-((E)-3-(3,4,5-trimethoxyphenyl)allylidene) and (E)-N-phenyl 2-((E)-3-(3,4,5-trimethoxyphenyl)allylidene)hydrazinecarbothioamides and their Cu(II) complexes

Abstract

Two slightly distorted octahedral complexes of copper(II) with (E)-2-((E)-3-(3,4,5-trimethoxyphenyl)allylidene)hydrazinecarbothioamide (L1) common name 3,4,5-trimethoxy-cinnamaldehydethiosemicarbazone and (E)-N-phenyl-2-((E)-3-(3,4,5-trimethoxyphenyl)-allylidene)hydrazinecarbothioamide (L2) common name 3,4,5-trimethoxycinnamaldehyde-4-phenylthiosemicarbazone have been synthesized. The two free ligands and their copper(II) complexes were characterized by spectroscopic techniques like FT-IR, FT-Raman, UV, EPR, Powder X-ray diffraction and cyclic voltammetry. The EPR spectra evidenced a rhombically distorted octahedron geometry for both the copper(II) complexes. The band gap calculations for the ligands L1, L2 and their complexes Cu(L1)2Cl2 and Cu(L2)2Cl2 were found to be 2.98, 2.61, 2.66 and 2.50 eV respectively. Cu(L1)2Cl2 and Cu(L2)2Cl2 have shown 50% of viability at 80 μg/ml and 60 μg/ml. The anti-oxidant activity study revealed that the compounds are good reductants of DPPH radical. Moderate to good anti-bacterial activity is shown by the compounds against the Gram-positive and Gram-negative bacteria. Molecular docking studies have been carried out to predict the orientation and binding mode of analysis in the active site. The synthesized ligand and complex well occupy (catalytic triad and adenine-binding site) in the active site of β-ketoacyl-acyl carrier protein synthase III enzyme, and also well occupy in helix 11 (in the DCS complex) of human estrogen receptor. Moreover they form water mediated hydrogen bond and hydrogen bond with Cys530 residue. Keywords: EPR spectra, HOMO-LUMO calculations, MDA-MB231 cell lines, Anti-oxidant activity, Molecular docking studies