Novel bioinspired acetato-bridged dinuclear nickel(II)-Schiff-base complex: Catechol oxidase and in vitro biological activity studies

A versatile bioinspired metallocatalyst [Ni2L2(NCS)(Ac)(H2O)(0.5)(MeOH)(0.5)].1.25H(2)O (HL = 2-((E)-(2-(pyridin-2-yl)ethylimino)methyl)-4-chlorophenol) has been synthesized from a Schiff-base ligand and characterized as reported earlier (Sanyal et al., 2016). It portrays catecholase activity as an oxygen dependent enzymatic radical catalysis under completely aerobic conditions (lambda(max) = 375 nm, epsilon = 1900 M-1 cm(-1)) against the model substrate 3,5-di-tert-butylcatechol (3,5-DTBC). Interestingly, Michaelis-Menten analysis of pseudo first-order reaction kinetics establishes that DMF medium provides a better catalytic pathway for catecholase activity (k(cat) = 2.8 x 10(-3) s(-1)) than acetonitrile (9.11 x 10(-4) s(-1)) under excess substrate conditions. Cell viability study, drug uptake assay, reactive oxygen species (ROS) formation, alteration of mitochondrial membrane potential (MMP), apoptosis study and DNA fragmentation demonstrates a significant dose dependent anti-leukemic activity on KG-IA (AML) and K562 (CML) cell lines. Notably, outstanding anti-bacterial property was also observed on multi-drug resistant E. coli and S. aureus bacteria. (C) 2016 Elsevier B.V. All rights reserved.