Ruthenium(II)/triphenylphosphine complexes : an effective way to improve the cytotoxicity of lapachol.

Abstract

This study reports on the synthesis of a new ruthenium(II) complex, cis-[Ru(PPh3)2(lap)2] (1) with two molecules of the natural product known as lapachol [lap = (2-hydroxy-3-(3-methyl-2-buthenyl)-1,4- naphthoquinone)] coordinated as bidentated by oxygen atoms and two monodentate PPh3 (triphenylphosphine) in a cis configuration. This neutral complex was characterized by spectroscopic analysis, single-crystal X-ray diffraction, elemental analysis, molar conductivity and cyclic voltammetry. In this study, ruthenium complex trans-[Ru(lap)(PPh3)2(phen)]PF6 (2) was used for comparison purposes. The interaction of ruthenium complexes (1) and (2) with CT-DNA was evaluated by UV–Vis and circular dichroism and it was observed that the complexes interact weakly with the CT-DNA. The fluorescence measurements suggest that complex (1) shows stronger interaction with HSA and BSA proteins compared to complex (2). Cytotoxicity assays against A549 (lung cancer), MDA-MB-231 (breast cancer) and V79 (non-tumoral lung) revealed that complex (2) is more active (lower IC50 values) than complex (1) and the cisplatin, used as a reference.