Interactive Profile between 1,4-Naphthoquinone Derivatives and Human Serum Albumin

The interactive profile between four 1,4-naphthoquinone derivatives (1-4) and human serum albumin (HSA) was studied by spectroscopic techniques and in silico calculations. The bimolecular quenching rate constant (kq ca. 1012 L mol-1 s-1) and the time-resolved fluorescence decays indicated a static fluorescence quenching mechanism. Thus, there is a spontaneous ground-state association, and based on both Stern-Volmer, modified Stern-Volmer, and van’t Hoff approaches, the association is moderate mainly driven by hydrophobic forces. The circular dichroism (CD) analysis indicated that until the proportion albumin:compound of 1:8 there is a weak perturbation on the structural content of albumin, while molecular docking results suggested subdomain IIA (site I), a positive electrostatic pocket, as the main binding site. Overall, even though the hydrogen atom replacement by methyl, fluorine, or chlorine atoms in the para position of the aromatic ring in the benzo[g]chromene-5,10-dione moiety changes the lipophilicity, it does not change the binding profile to HSA.