Production and characterization of α-glucosidase inhibitory peptides from sweet potato protein by ultrasound-assisted enzymatic hydrolysis and in vitro gastrointestinal digestion

Effects of energy divergent (EDU) and gathered ultrasound (EGU) at 40 W/L assisted Alcalase, Papain and Flavourzyme hydrolysis on production of α-glucosidase inhibitory peptides from sweet potato protein (SPP) were investigated, as well as impact of in vitro gastrointestinal digestion (GID) on changes of their characterization, to explore new preparation technology and potential source of α-glucosidase inhibitory peptides. EDU and EGU assisted enzymatic hydrolysis markedly enhanced α-glucosidase inhibitory activity and yield of all SPP hydrolysates (SPPH). Among them, SPPH by EGU-assisted Alcalase, Papain and Flavourzyme (APF) hydrolysis exhibited the highest α-glucosidase inhibitory activity (IC₅₀ 0.26 mg/mL) and yield (86.39%), of which the inhibitory activity was highly preserved after in vitro digestion. MW 1–2 kDa peptides obtained from SPPH by EGU-APF after GID (EGU-APF-S) showed high α-glucosidase inhibition, from which two novel α-glucosidase inhibitory peptides AIWGAGGGGLR and FHDPMLR were identified with IC₅₀ of 0.087 and 0.036 mg/mL respectively. Molecular docking revealed that stronger interaction between FHDPMLR and α-glucosidase was attributed to more hydrogen bonds and electrostatic interactions as compared to AIWGAGGGGLR. Therefore, SPPH by EGU-APF can be a potential source of α-glucosidase inhibitory peptides.