DNA binding and topoisomerase II inhibitory activity of water-soluble ruthenium(II) and rhodium(III) complexes

Water-soluble piano-stool arene ruthenium complexes based on 1-(4-cyanophenyl)imidazole (CPI) and 4-cyanopyridine (CNPy) with the formulas [(eta(6)-arene)RuCl2(L)] (L = CPl, eta(6)-arene = benzene (1), p-cymene (2), hexamethyl benzene (3); L = CNPy, eta(6)-arene = benzene (4), p-cymene (5), h examethylbenzene (6)) have been prepared by our earlier methods. The molecular structure of [(eta(6) -C6Me6)RuCl2(CNPy)] (6) has been determined crystallographically. Analogous rhodium(III) complex [(eta(5)-C5Me5)RhCl2(CPI)] (7) has also been prepared and characterized. DNA interaction with the arene ruthenium complexes and the rhodiurn complex has been examined by spectroscopic and gel mobility shift assay; condensation of DNA and B -> Z transition have also been described. Arene ruthenium(II) and EPh3 (E = P, As)-containing arene ruthenium(II) complexes exhibited strong binding behavior, however, rhodium(111) complexes were found to be Topo 11 inhibitors with an inhibition percentage of 70% (7) and 30% (7a). Furthermore, arene ruthenium complexes containing polypyridyl ligands also act as mild Topo 11 inhibitors (10%, 3c and 40%, 3d) in contrast to their precursor complexes. Complexes 4-6 also show significant inhibition of beta-hematin/hemozoin formation activity.