Interactions of a Ruthenium‐Ketoprofen Compound with Human Serum Albumin and DNA: Insights from Spectrophotometric Titrations and Molecular Docking Calculations

The compound [Ru 2 O(keto) 2 (py) 6 ](PF 6 ) 2 , keto=ketoprofen and py=pyridine, interacts with calf thymus‐DNA with K b =1.08×10 4 M −1 . It efficiently quenches HSA fluorescence in different temperatures, with Ksv values in the 10 4 –10 5 M −1 range, both by dynamic and static mechanisms. The data provided by the double logarithmic and van't Hoff approximations indicated a moderate (K b ≈10 4 M −1 ) and spontaneous (ΔG<0) interaction, being enthalpically driven (ΔH=−27.1 kJ mol −1 and ΔS=−5.3 J mol −1 K −1 ). Molecular docking calculations confirmed that the binuclear compound interacts with HSA more strongly than with DNA. The occurrence of a high contribution from electrostatic forces was observed, fully consistent with the bicationic nature of [Ru 2 O(keto) 2 (py) 6 ](PF 6 ) 2 . The molecular docking results also revealed that the interaction occurs in an external subdomain, explaining the lack of significant conformational changes in the protein, as probed by circular dichroism spectra.