Impact of the carbon chain length of novel palladium(II) complexes on interaction with DNA and cytotoxic activity.

A series of Pd(II) complexes with a benzenealkyl dicarboxlate chain, with the formulas [Pd(L(n))(bipy)].mH(2)O (bipy = 2,2'-bipyridine, complex 1: L(1) = phenylmalonate, m = 2.5; complex 2: L(2) = benzylmalonate, m = 1; complex 3: L(3) = phenethylmalonate, m = 2; complex 4: L(4) = phenylpropylmalonate, m = 5), have been prepared in an attempt to correlate factors about the carbon chain of the compounds with DNA binding and cytotoxic activity. The binding of complexes with fish sperm DNA (FS-DNA) was carried out by UV absorption and fluorescence spectra. A gel electrophoresis assay demonstrated the ability of the complexes to cleave the pBR322 plasmid DNA. The cytotoxic effects of these complexes were examined on four cancer cell lines, HeLa, Hep-G2, KB, and AGZY-83a. The four complexes exhibited cytotoxic specificity and a significant cancer cell inhibitory rate. An apparent dependence of DNA-binding properties and cytotoxicity on the carbon chain length was obtained: the longer the carbon chain length, the higher the efficiency of DNA-binding and the greater the cytotoxicity.