Influence of carboxylic acid functionalities in ruthenium (II) polypyridyl complexes on DNA binding, cytotoxicity and antioxidant activity: Synthesis, structure and in vitro anticancer activity

Four new Ru(II) complexes [RuHCl(bpy)(PPh3)(CO)] (1), [RuHCl(bpy)(AsPh3)(CO)] (2) (bpy = 2,2′-bipyridine), [RuCl(HL)(PPh3)2(CO)] (3) and [RuCl(HL)(AsPh3)2(CO)] (4) (HL = 2,2′-bipyridine-4,4′-dicarboxylic acid) were synthesized and characterized. X-ray diffraction was used to characterize 3 in solid state. The interactions of these complexes with DNA were explored by different techniques which revealed that the complexes could bind to CT-DNA through non-intercalation. The in vitro cytotoxic and antioxidant activities of the complexes validated against a panel of cancer cell lines and free radicals showed that 3 and 4 possess quite high anticancer and antioxidant activities over 1, 2 and standard drugs. An apparent dependence of biological activities on incorporation of COOH in bipyridine moiety was noticed: Inclusion of COOH caused significant differences in DNA binding, cytotoxicity and antioxidant activity.

Graphical abstractThe impact of COOH on various biological activities revealed that complexes which do not contain COOH showed good DNA binding and complexes which contain COOH behaved as excellent antitumor agents/antioxidants.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Four new ruthenium(II) complexes have been synthesized and characterized. ► The impact of COOH on various biological activities have been investigated. ► The DNA interactions of these complexes were studied by a variety of techniques. ► The cytotoxic activity was evaluated against a panel of cancer cell lines. ► The antioxidant activity against various radicals have also been examined.