Synthesis, Cytotoxicity Of N-sulfonyl-L-amino Acid Dianion And Diamine/Diimine Palladium(â…¡)/ Platinum(â…¡) Mixed-ligand Complexes In Vitro

To overcome the drawbacks of platinum-based anticancer drugs, we have synthesized forty-six palladium(II)/platinum(II) mixed-ligand complexes with N-sulfonyl-L-amino acid dianion and diamine. The complexes have been characterized by elemental analysis,IR,MS and 1H NMR spectra techniques. Crystal and molecular structures of five complexes were determined by X-ray diffraction. In all complexes, palladium(II) and platinum(II) ion coordinated to the deprotonated amide nitrogen and one carboxylic oxygen of the amino acid molecule, N atoms of the diamine or diimine molecule in a square-planar geometry as a five-membered chelate ring. The complexes have been assayed for cytotoxicity in vitro against four cell lines : human immature granulocyte leukemia (HL-60), humanliver carcinoma (Bel-7402), human gastrocarcinoma (BGC-823) and human nasopharyngeal carcinoma (KB) by SRB (Sulfonylrhodamine B) and MTT (Methylthiazolyl tetrazolium) methods. The results indicated that the complexes have selectively inhibited the growth of cancer cells. Cytotoxicities were different based on species of metals, diamine/diimine and amino acids. Pd complexes obtained better cytotoxicityes compared with Pt complexes. Complexes with phen as ligands have better activities than en, bipy or bqu. And N-sulfonyl-L-leucine and N-sulfonyl-L-phenylalanine exhibit optimistic activities. Among en, bipy, phen and bqu, phen has lowest IC50 which might because that phen have the most efficient conjugate ring to insert into DNA to inhibit the duplication of DNA. Also as the R group of the amino acids part became longer, the activities of the complexes have been gradually improved.