Pt(II) pyridinium amidate (PYA) complexes: Preparation and in vitro anticancer activity studies

N-[1-Alkylpyridin-4(1H)-ylidene] amides (PYAs), also known as pyridinium amidates, are a class of recently introduced ligands for transition metal ions. Herein we report the synthesis of the Pt(PYA) complexes [PtCl(DMSO)(HL)]Cl-2 (1), [Pt(CH3)(DMSO)(L)]Cl (2) and [Pt(CH3)(PPh3)(L)]Cl (3) (L= N-(1-benzylpyridin- 4(1H)-ylidene) picolinamide). L and [HL](+) act as bidentate ligands coordinating through the pendant pyridine and either the amidate oxygen or nitrogen atoms to give the corresponding N, O or N, N linkage isomers. DFT calculations were carried out to determine the most energetically favorable isomeric forms of these compounds. For 1 the N, O coordination mode was lower in energy, while for 2 and 3 hardly any difference was found. In vitro cytotoxicity studies of [HL] Cl and 1 in human colorectal carcinoma HCT116, non-small cell lung carcinoma NCI-H460, and cervical carcinoma SiHa cells showed that both compounds are cytotoxic in the low mu M range. (C) 2016 Elsevier B.V. All rights reserved.