Antioxidant Activity of Ruthenium(Ii) Complexes Containing Tridentate Triamines and Their Capability to Inhibit Xanthine Oxidase

Biological activities of organoruthenium complexes [chloro [N,N '-[(2,6-pyridinediyl-kappa N) diethylidyne] bis-[benzenamine-kappa N]] [N-[(2-pyridinyl-kappa N) methylene] benzenesulfonamide-kappa N] ruthenium(II)] chloride (Cmplx 1), [chloro [2,2 '-(2,6-pyridinediyl-kappa N) bis [1H-benzimidazole-kappa N-3]][N-[(2-pyridinyl-kappa N) methylene] benzenesulfonamide-kappa N] ruthenium(II)] chloride (Cmplx 2), and [chloro[2,6-di(1H-pyrazol-3-yl-kappa N-2) pyridine-kappa N] [N-[(2-pyridinyl-kappa N) methylene] [benzenesulfonamide-kappa N] ruthenium(II)] chloride (Cmplx 3) have been studies. The compounds were tested for in vitro biological activity on test models including 2,2-diphenyl-1-picryl-hydrazyl (DPPH) reducing power, superoxide anion radical-scavenging activity, and lipid peroxidation activity by ferric thiocyanate. It is established that Cmplx 2 with benzimidazole ligand displays significant xanthine oxidase inhibitory activity (IC50 = 53.80 +/- 2.69 mu M), DPPH free radical scavenging activity (79.49 +/- 1.59), and superoxide anion radical scavenging activity (75.73 +/- 2.85%). The coordination of benzenamine and benzenesulfanoamine ligands reduces lipid peroxidation as observed in the case of Cmplx 1 (87.17 +/- 3.88%) and the higher reducing power of Cmplx 1 obtained at all concentrations. It was concluded from the test results that organoruthenium complexes showed much better antioxidant activity than expected.