Monofunctional platinum complexes showing potent cytotoxicity against human liver carcinoma cell line BEL-7402

Three novel Pt(II) complexes [PtL1'Cl] I (L-1' = glycine-N'-8-quinolylamide), [PtL2'CIl]II(L-2' = L-alanine-N'-8-quinolylamide), and [PtL3Cl] III [L-3 = N-(tert-butoxycarbonyl)-L-methionine-wN'-8-quinolylamide] have been synthesized and characterized. The crystal structure of complexes II and III showed that the ligands are three-coordinated with only one Cl- as the leaving group. Complex II crystallized in the monoclinic system with space group P2(1), a = 9.502(2) Angstrom, b = 4.724(1) Angstrom, c = 14.800(3) Angstrom, while complex III crystallized in the orthorhombic system with space group P2(1)2(1)2(1), a = 5.441(1) Angstrom, b = 12.978(3) Angstrom, c = 29.438(6) Angstrom. These complexes have been tested against a wide range of tumor cell lines including BEL-7402, HCT-116, SPC-A4, MOLT-4, P388, HL-60, A-549, SGC-7901, MKN-28, and HO-8910. Complex III is highly cytotoxic against the HCT-116 (IC50 = 0.38 muM), SPC-A4 (IC50 = 0.43 muM), BEL-7402 (IC50 = 0.43 muM), and MOLT-4 (IC50 = 0.61 muM) cell lines. The cell line most sensitive to III is human liver carcinoma cell line BEL-7402, which has a response rate of 75.1% at 6.6 x 10(-7) M, nearly 6 times higher than that of cisplatin.