DNA/BSA interaction of platinum(II) complexes with phenothiazine and N-methylphenothiazine

Abstract

In the present study, the interactions of two platinum(II) complexes of the general formula cis-[PtCl2(L)(CH3CN)], L is phenothiazine (phtz, Pt1) and N-methylphenothiazine (NMephtz, Pt2) with calf thymus DNA (ct-DNA) and bovine serum albumin (BSA) were studied by fluorescence emission spectroscopy to check their binding affinity towards these biomolecules for possible insights into the mode of their biological activity. A remarkable decrease in BSA fluorescence intensity after the addition of the complexes Pt1 and Pt2 and high values of the binding constants are in accordance with their high affinity toward this protein. On the other hand, the low binding affinity of the studied platinum(II) complexes to ct-DNA-EthBr system (EthBr is ethidium bromide, a well-known DNA intercalator) was observed. This has indicated that proteins could be more favorable binding sites for these platinum(II) complexes in comparison to the nucleic acids. Interestingly, Pt1 complex has shown a higher binding affinity toward DNA than Pt2, while the latter complex is a more efficient BSA binder.