Synthesis, characterization and antitubercular activities of novel pyrrolyl hydrazones and their Cu-complexes

Abstract

Novel pyrrolyl hydrazones and their copper complexes have been synthesized and characterized using analytical and spectral techniques to show the tetrahedral geometry for Cu(II) complexes. Biological activities of hydrazones have been assessed to understand the role of metal ion on their biological activity and the effect of pyrrolyl hydrazones. In vitro antitubercular activity against Mycobacterium tuberculosis of the metal complexes (13b and 13r) exhibited the highest antitubercular activity that are quite close to rifampicin (0.4 μg/mL), giving a MIC of 0.8 μg/mL. All other compounds showed good activity with the MIC values ranging from 1.6 to 100 μg/mL. A comparative study of inhibition values of the ligands and their complexes showed higher antimicrobial activity of the complexes than the ligands. Some compounds have a good activity against InhA and in particular, compounds 12r, 13b and 13r exhibited more than 60% binding with the enzyme even at 5 μM (exhibited good IC50 upto 2.4 μM). Most of the active molecules have a very less cytotoxicity against the human lung cancer cell-line A549. The docking and 3D-QSAR studies have been carried out to provide some insights into the mechanism of action for this class of compounds.

Keywords: Anti-tubercular activity; Cytotoxicity activity; Enzyme inhibition studies; Pyrrolyl Cu-complexes; Pyrrolyl Schiff bases; Surflex docking.