Crystal structures and in vitro anticancer studies on new unsymmetrical copper(II) Schiff base complexes derived from meso-1,2-diphenyl-1,2-ethylenediamine: a comparison with related symmetrical ones

Abstract

Two new unsymmetrical copper(II) Schiff base complexes, CuLn(py)ClO4 (n = 1, 2) in which Ln represents a tridentate N2O type Schiff base ligand, were synthesized. Lns were derived from monocondensation of meso-1,2-diphenyl-1,2-ethylenediamine with salicylaldehyde or 3-methoxysalicylaldehyde. The reaction between CuLn(py)ClO4 and other salicylaldehyde derivatives resulted in new N2O2 unsymmetrical tetradentate CuII complexes, CuL3�6. Crystal structures of CuL1(py)ClO4, CuL4, and CuL5 were obtained. These new complexes as well as a series of related symmetrical ones (i.e. CuL7�12) were tested for their in vitro anticancer activity against human liver cancer cell line (Hep-G2) by MTT and apoptosis assay. All of the complexes showed considerable cytotoxic activity against tumor cell lines (IC50 = 5.13�16.24 μg mL�1). The symmetrical CuL7 was the most potent anticancer derivative (IC50 = 5.13 μg mL�1) compared to the control drug 5-FU (IC50 = 5.4 μg mL-1, p < 0.05). Flow cytometry experiments showed that the copper derivatives especially CuL2(py)ClO4 and CuL7 induced more apoptosis on Hep-G2 tumor cell lines compared to 5-FU. © 2016 Informa UK Limited, trading as Taylor & Francis Group