DINUCLEAR PALLADIUM(II) COMPLEXES CONTAINING 2 MONOFUNCTIONAL [PD(EN)(PYRIDINE)CL](- SYNTHESIS, CHARACTERIZATION, CYTOTOXICITY AND KINETIC-STUDIES OF DNA-BINDING() UNITS BRIDGED BY SE OR S )

Two novel dinuclear palladium(II) complexes, ([Pd(en)Cl](2)(bpse)}(NO3 )(2) (1) and {[Pd(en)Cl](2) (bpsu)}(NO3)(2) (2), (where an is ethylene diamine; bpse is bis(3-methyl-4-pyridyl) selenide; bpsu is bis(3-methy l-4-pyridyl) sulfide) have been synthesized. The complexes have been c haracterized by elemental analysis, IR, H-1 NMR, and C-13 NMR. They ha ve been assayed for antitumor activity in vitro against the mice leuke mia L1210 and the human coloadenocarcinoma HCT8 cell lines. The result s show that compound 1 has a lower I.D.(50) value against the two canc er cell lines as compared to compound 2; the compounds also shows a lo wer I.D.(50) value than cisplatin against the HCT8 cell line, but a hi gher I.D.(50) value than cisplatin against the L1210 cell line. Bindin g studies indicate that compound 1 possibly interacts with DNA bg a no nintercalative mode. Kinetics oi binding of the two compounds to DNA a re firstly studied using ethidium bromide as a fluorescence probe with stopped-flow spectrophotometer under pseudo-first-order condition. Th e stronger binding of two steps in the process of the compounds intera cting with DNA are observed, and the k(obs) and E-a of binding of the two steps (where k(obs) is the observed pseudo-first-order rate consta nt, E-a is the observed energy of activation) are obtained. (C) 1998 E lsevier Science Inc. All rights reserved.