Interaction of organoruthenium(II)-polypyridyl complexes with DNA and BSA.

The interaction of four arene ruthenium complexes [(η6-p-cymene)Ru(Me2dppz)Cl]PF6 (1) with Me2dppz = 11,12-dimethyldipyrido[3,2-a:2',3'-c]phenazine, [(η6-p-cymene)Ru(aip)Cl]PF6 (2) with aip = 2-(9-anthryl)-1H-imidazo[4,5-f][1,10] phenanthroline), ([(ƞ6-toluene)Ru(ppf)Cl]PF6) (3) and ([(ƞ6-p-cymene)Ru(ppf)Cl]PF6) (4) with ppf = pyrido[2',3':5,6] pyrazino[2,3-f][1,10]phenanthroline with calf thymus DNA were investigated. All of four complexes exhibit DNA-binding activity. UV-Vis spectroscopic studies revealed the intrinsic binding constants of the order 104 M-1 of magnitude, indicating non-intercalative mode. Fluorescence quenching analysis showed that all complexes interfere with intercalator ethidium bromide and minor groove binder Hoechst 33258 by a singular non-intercalative mode with extent that differs by two orders of magnitude. Gel electrophoresis results on DNA cleavage assay demonstrated that all complexes produced conformational changes of supercoiled circular plasmid pUC19 in concentration dependent way. The results of fluorescence titration bovine serum albumin by 1, 2, 3 and 4 showed that all complexes significantly quench tryptophan residues fluorescence through a static quenching mechanism. The antimicrobial activity against both Gram-positive and Gram-negative bacteria analyzed. Complex 1 was most active, even on Escherichia coli was more active than positive control compound.