Biophysical characterization of interactions between falcarinol-type polyacetylenes and human serum albumin via multispectroscopy and molecular docking techniques.

Aliphatic polyacetylenes are nutraceuticals. Interactions of the polyacetylenes falcarinol, panaxydol and falcarindiol with human serum albumin (HSA) were studied via steady-state and time-resolved fluorescence, UV–Vis, circular dichroism and Fourier transform infrared (FT-IR) spectroscopies and molecular docking. The value of Stern-Volmer quenching constant ( K SV ) decreased with temperature increase in fluorescence quenching experiments, and the average fluorescence lifetime ( τ ) was calculated between 5.25 and 5.40 ns according to time-resolved fluorescence. The results indicated that the quenching mechanism of HSA by the three falcarinol-type polyacetylenes (FTPs) is a static process. FTPs most probably bind HSA at site II alone, located in domain IIIA, as evidenced by competitive ligand displacement and molecular docking studies. The FTPs could induce slight conformational and microenvironmental changes of HSA as determined by three-dimensional fluorescence, circular dichroism and FT-IR measurements, and energy transfer observed. The findings can offer important insights for the further design of potential biologically active FTPs. [ABSTRACT FROM AUTHOR]