Phenolic Composition, Antioxidant Properties, and Inhibition toward Digestive Enzymes with Molecular Docking Analysis of Different Fractions from Prinsepia utilis Royle Fruits

The present study investigated the phenolic profiles and antioxidant properties of different fractions from Prinsepia utilis Royle fruits using molecular docking analysis to delineate their inhibition toward digestive enzymes. A total of 20 phenolics was identified and quantified. Rutin, quercetin-3-O-glucoside, and isorhamnetin-3-O-rutinoside were the major phenolic compounds in the total phenolic fraction and flavonoid-rich fraction. The anthocyanin-rich fraction mainly contained cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside. All of the fractions exhibited strong radical scavenging activities and good inhibition on cellular reactive oxygen species (ROS) generation in H₂O₂-induced HepG2 cells, as evaluated by DPPH and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays. Moreover, the powerful inhibitory effects of those fractions against pancreatic lipase and α-glucosidase were observed. The major phenolic compounds that were found in the three fractions also showed good digestive enzyme inhibitory activities in a dose-dependent manner. Molecular docking analysis revealed the underlying inhibition mechanisms of those phenolic standards against digestive enzymes, and the theoretical analysis data were consistent with the experimental results.