Screening and Identification of Novel Peony Seed Peptides with High Antioxidant and Hypoglycemic Activities: Enzymolysis, In vitro Digestion and Molecular Docking.

Abstract

The potential of peony seed meal protein (PSMP) as a source of bioactive peptides has not been fully explored. Three novel peptides (PADAPF, FDQGNF, AVFPSIVGRPR) with antioxidant and hypoglycemic activities were screened from the gastrointestinal digest (GID) of alcalase-hydrolyzed PSMP via enzymolysis, in vitro digestion, and molecular docking. Among four proteases (alcalase, protamex, papain, trypsin), alcalase hydrolysate (ALH) exhibited the highest digestive stability after in vitro gastrointestinal digestion. ALH-GID retained strong DPPH (1,1-diphenyl-2-picrylhydrazyl)/ABTS (2,2'-azinobis (3-ethyl-benzothiazoline-6-sulphonic acid) diammonium salt) radical scavenging ability (0.44 ± 0.01 mg hydrolysate/mL and 0.67 ± 0.04 mg hydrolysate/mL, respectively), reducing power (0.617) and α-glucosidase inhibitory activity (IC₅₀ = 0.29 mg hydrolysate/mL). In HepG2 cells, ALH-GID reduced reactive oxygen species (ROS) and malondialdehyde (MDA) by 31.71 and 35.47%, increased superoxide dismutase (SOD) and catalase (CAT) activities by 24.16 and 32.72%, and enhanced glucose consumption in insulin-resistant cells by 72.10%. Molecular docking suggested that PADAPF, AVFPSIVGRPR, and FDQGNF as candidate peptides may contribute to the observed activities, with PADAPF showing preferential binding to Keap1, AVFPSIVGRPR to α-glucosidase, and FDQGNF exhibiting dual-target binding. These findings highlight the potential of PSMP for functional food development.