A Comparative Study of In Vitro Cytotoxic,Antioxidant, and Antimicrobial Activity of Pt(II), Zn(II), Cu(II), and Co(III) Complexes with N‐heteroaromatic Schiff Base (E)‐2‐[N′‐(1‐pyridin‐2‐yl‐ethylidene)hydrazino]acetate

In search for novel biologically active metal based compounds, an evaluation of in vitro cytotoxic, antioxidant, and antimicrobial activity of new Pt(II) complex and its Zn(II), Cu(II), and Co(III) analogues, with NNO tridentately coordinated N‐heteroaromatic Schiff base ligand (E)‐2‐[N′‐(1‐pyridin‐2‐yl‐ethylidene)hydrazino]acetate, was performed. Investigation of antioxidative properties showed that all of the compounds have strong radical scavenging potencies. The Zn(II) complex showed potent inhibition of DNA cleavage by hydroxyl radical. A cytotoxic action of investigated compounds was evaluated on cultures of human promyelocitic leukaemia (HL‐60), human glioma (U251), rat glioma (C6), and mouse melanoma (B16) cell lines. It was shown that binuclear pentacoordinated Zn(II) complex possesses a strong dose‐dependent cytotoxic activity, of the same order of magnitude as cisplatin on B16, C6, and U251 cells. Furthermore, Zn(II) complex causes oxidative stress‐induced apoptotic death of HL‐60 leukemic cells, associated with caspase activation, phosphatidylserine externalization, and DNA fragmentation.