Enhanced solubility, thermal stability and antioxidant activity of resveratrol by complexation with ovalbumin amyloid-like fibrils: Effect of pH

Abstract

Resveratrol (RES) has attracted much attention because of its many potential health benefits. However, its poor aqueous solubility and chemical instability hinder its application. In this study, ovalbumin (OVA) fibrils (OVAF) were used as nanocarriers to improve the aqueous solubility, thermal stability and antioxidant activity of hydrophobic RES, and the effects of pH were also investigated. The results showed that after complexation with OVAF at pH 2.0, the aqueous solubility of RES was 12.3 times higher than that of free RES. Transmission electron microscope images revealed that after incorporating with RES, the OVAF assembled into entangled aggregates due to the interaction. Intrinsic fluorescence spectra, Fourier transform infrared spectra and zeta potential measurements showed that the hydrophobic interactions, hydrogen bonds and electrostatic interactions were mainly contributed to the formation of OVAF/RES complex. Moreover, X-ray diffraction results proved that RES was encapsulated in fibrils with an amorphous form. It was noteworthy that OVAF at pH 2.0 had the highest binding constant with RES, and thus it exhibited the best protective effect on thermal degradation of RES. In addition, the antioxidant capacity of RES was drastically improved through the complexation with OVAF. Hence, these results suggested that OVA amyloid-like fibrils may be a suitable nanocarriers for hydrophobic nutrients.