Quercetin-phenylalanine 3d-transition metal-based {Co(II), Ni(II) & Cu(II)} intercalative therapeutic agents: DNA & BSA interaction studies in vitro and cleavage activity.

New Quercetin-phenylalanine metal-based therapeutic agents of the formulation [Qu(Phe)M(II).(H2O)2].NO3 where M(II) = Co(II) and Ni(II) and [Qu(Phe)Cu(II).(H2O)2] were synthesized and their structure was predicted by IR, UV-vis, EPR and ESI-MS spectroscopic techniques. The bio-molecular interaction studies of the Quercetin-phenylalanine complexes, 1-3 with ct-DNA and BSA were performed using a battery of complimentary biophysical techniques. The corroborative results of these experiments revealed strong binding propensity via electrostatic interactions probably through minor grove binding towards ct-DNA, therapeutic target. The binding affinity of Quercetin-phenylalanine complexes 1-3 was quantified by determining binding constants values, Kb, Ksv, and the magnitude of binding propensity followed the order 3 > 1 > 2, implicating the preferential binding of Cu(II) complex 3 with ct-DNA. The cleavage studies were performed with complexes using gel electrophoretic mobility assay. The complexes 1-3 demonstrated efficient cleaving ability by the hydrolytic cleavage pathway involving hydroxyl (OH) radicals. BSA binding profile of Quercetin-phenylalanine metal therapeutics 1-3 was studied in order to understand the drug carrier potential of these compounds and found that complex 3 was capable of binding preferentially with BSA as compared to other complexes.