Determining role of structure in the stability increase of purple sweet potato anthocyanins bound to proteins

Abstract

Abstract The stability of anthocyanins is poor, seriously affecting their biological activity. The effect of bovine serum albumin (BSA) on the stability of purple sweet potato anthocyanins (PSPA) and its mechanism of action was investigated. Eleven anthocyanins in purple sweet potato were identified, and the stability of PSPAs with different structures combined with BSA was analyzed separately. The results showed an interaction between BSA and PSPA by UV absorption and fluorescence spectra, in which PSPA could cause a fluorescence burst of BSA, and the binding of PSPA to BSA was in the form of 1:1. In addition, the interactions are spontaneous, and hydrophobic interactions dominate. The binding amount study showed that 1 mol/L of BSA binds 3 mol/L of PSPA. The results of zeta potential and particle size showed that the absolute value of the possibility was around 30 mV, and BSA could combine with PSPA to form nanoparticles with high stability. Molecular docking analysis showed that PSPA could be well embedded in the structural cavities of BSA. The binding sites were near sites I and II, hydrogen bonding and hydrophobic interactions act as the main drivers of binding. Finally, after binding, BSA could effectively improve the stability of PSPA, especially for different structures of PSPA. The binding of diacylated anthocyanins was more stable than monoacylated ones, peonidin was more stable than cyanidin, and caffeoyl was more stable compared to p‐hydroxybenzoyl and feruloyl.

Keywords

• anthocyanin
• bovine serum albumin
• conformational relationships
• fluorescence spectroscopy
• liquid chromatography
• purple sweet potato