A novel platinum( ii ) anticancer complex of danysl bis(2-benzothiazolylmethyl)amine with dimethyl sulfoxide as a leaving group: synthesis, cytotoxicity, interaction with DNA and human serum albumin

A novel mononuclear platinum( ii ) complex, [Pt L (DMSO)Cl]Cl ( 1 , here L = danysl bis(2-benzothiazolylmethyl)amine), has been synthesized and characterized by ESI-MS, IR spectrum, 1 H NMR, 13 C NMR, molar conductivity, and elemental analysis. The results suggest that in the structure of complex 1 , a platinum( ii ) ion is coordinated by a tertiary amine nitrogen, a benzothiazole nitrogen, a DMSO sulfur, and an exogenous chlorine ion to form one square mononuclear structure. Complex 1 exhibits a cytotoxicity comparable to that of cisplatin against HeLa cell line and more potent activities against A-549 and MCF-7 cell lines. Compared to those of L , the potent cytotoxicity of 1 should result from the coordination of Pt( ii ). DNA binding experiments demonstrate that 1 could strongly bind to calf thymus DNA (CT-DNA) by a groove binding mode accompanied with a moderate intercalation and induce a visible conformational variation of DNA. Investigation of the reaction of 1 with 5′-GMP by ESI-MS shows that complex 1 could first form a 1 : 1 adduct [Pt L (DMSO)(GMP) − 2Na + H] + with 5′-GMP and react further with a second equivalent of 5′-GMP to form a 1 : 2 adduct [Pt L (DMSO)(GMP) 2 − 4Na + 3H] + , which is similar to those of [Pt(en)(DMSO)Cl]Cl and cisplatin. Therefore, the anticancer mechanism of these compounds might well be related to each other. The evalution of the protein binding ability shows that complex 1 could bind to human serum albumin (HSA) with a moderate binding affinity, quench the intrinsic fluorescence of HSA, and destroy the tertiary structure of HSA.