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.
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