Polyphenol-protein interaction (PPI) is reversible in that polyphenol-protein complex can be dissociated and release the free polyphenols. The aim of this study is to evaluate the contribution of polyphenol-protein interaction on improving the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging capacity of polyphenols. The DPPH radical scavenging potential of polyphenols was determined from 1 to 7 days under aerobic condition. The DPPH radical scavenging capacity of polyphenols depended on the structures of dietary polyphenols and gallic acids. The DPPH radical scavenging percentages of Group H polyphenols were weakened when kept in room temperature from 1 to 7 days. BSA rapid weakened the DPPH radical scavenging activity of polyphenols on the first day. However, the DPPH scavenging capacities of polyphenols in the presence of BSA overwhelmingly improved with increasing time. These results illustrated that BSA not only prolongs the effective time, but also improved the DPPH radical scavenging potential of polyphenols. The increasing DPPH scavenging percentages of polyphenols slightly decreased with increased affinities of BSA-polyphenol complexes.
Keywords: Polypenol-protein interaction, DPPH scavenging capacity, Protein binding, Polyphenols, Gallic acids, antioxidant, ethylbenzothiazoline, apigenin, puerarin, epicatechin