Phenolic characterization, antioxidant and α-glycosidase inhibitory activities of different fractions from Prinsepia utilis Royle seed shell using in vitro and in silico analyses

In this study, the free, esterified, and insoluble-bound phenolics in Prinsepia utilis Royle seed shell were identified, and their antioxidant and alpha-glycosidase inhibitory activities were studied. The main alpha-glycosidase inhibitor was screened by molecular docking and in vitro experiments. The interaction mechanism between the main inhibitor and alpha-glycosidase was studied by molecular dynamics simulation. A total of 18 phytochemicals including 14 phenolic compounds were identified, of which rutin and (-)-epicatechin were the main phenolic compounds. The esterified phenolic extract had the strongest antioxidant activity, while the free phenolic extract showed the best alpha-glycosidase inhibitory activity. Rutin was found to be the main inhibitor of alpha-glycosidase and can effectively bind to the active site of alpha-glycosidase through hydrogen bonds and van der Waals force. This research demonstrated the potentials of P. utilis seed shell as a good source of phenolic compounds that can further be utilized for food and/or pharmaceutical applications.