Potential new inorganic antitumour agents from combining the anticancer traditional Chinese medicine (TCM) liriodenine with metal ions, and DNA binding studies

Liriodenine (L), an active component of the anticancer traditional Chinese medicine (TCM), was isolated from Zanthoxylum nitidum. Its reactions with Pt(II) and Ru(II) afforded three metal complexes: cis-[PtCl2(L)] (1), cis-[PtCl2(L)(DMSO)] (2), and cis-[RuCl2(L)(DMSO)(2)]center dot 1.5H(2)O (3), the crystal structures of L, 2 and 3 were determined by single-crystal X-ray diffraction methods. These complexes were fully characterized by elemental analysis, IR spectrophotometry, H-1 and C-13 NMR spectroscopies, and ES mass spectrometry. The in vitro cytotoxicity of L and complexes 1-3 against 11 human tumour cell lines was assayed. The metal-based compounds exhibit enhanced cytotoxicity vs. free L, suggesting that these compounds display synergy in the combination of metal ions and liriodenine. The binding properties of L and its complexes 1-3 to ct-DNA were investigated through UV-vis, fluorescence, CD spectra, viscosity and agarose gels electrophoretic measurements.