Resveratrol induces thermal stabilization of human serum albumin and modulates the early aggregation stage

Several phenolic compounds bind to proteins and show the ability to interfere with their aggregation process. The impact of the natural polyphenol resveratrol on the stability and heat induced aggregation of human serum albumin (HSA) was investigated by differential scanning calorimetry (DSC), attenuated total reflectance Fourier transform infrared (ATR-FTIR), UV-vis absorbance, ThT fluorescence, atomic force microscopy (AFM) and molecular modeling. The binding of resveratrol to HSA improves the stability of the protein to thermal unfolding, particularly for the energetic domain containing the ligand binding site, as modeled by computational techniques. The thermal unfolding is irreversible and after the melting the protein aggregates, either with or without the ligand. The kinetics of HSA aggregation between 70 and 80 degrees C shows an exponential growth of the absorbance change and it slows down when resveratrol is added. The aggregates have fibril-like morphology and resveratrol attenuates the formation of beta-structured species. The overall results suggest that resveratrol stabilizes the protein structure and modulates the formation of fibrils along the initial stage of the HSA aggregation pathway.