Multifunctional ACE-inhibitory peptides with antioxidant and ferrous-chelating capacities from ginkgo kernel glutelin-2 hydrolysates: Identification, virtual screening, inhibition mechanism, and gastrointestinal stability studies

Ginkgo kernel is an underutilised functional protein resource. To improve its utilization in the food industry, this study investigated the identification, virtual screening, and mechanisms of angiotensin-I-converting enzyme (ACE)-inhibitory peptides with antioxidant and ferrous-chelating abilities from Ginkgo kernel glutelin-2 hydrolysates via intergrade in vitro and in silico methods. Among the seven oligopeptides identified, Tyr-Glu-Gly-Asp-Asn-Gly-Ala-Gly-Tyr (YEGDQGAGY, 959.1 Da) and Pro-Cys-His-His-Tyr (PCHHY, 655.8 Da) exhibited high ACE-inhibitory activity (IC 50 : 76.7 and 186.6 μmol/L), ferrous-binding ability (33.8 and 16.4 mg/g), and scavenging abilities on hydroxyl (84.6% and 93.3%), ABTS (79.5% and 81.5%) and superoxide radicals (45.4% and 84.6%, respectively). YEGDQGAGY and PCHHY formed thirteen and three hydrogen bonds with Ala354, Lys511, Tyr520, and Gln281 in ACE's substrate-binding centre, respectively. The amino and carboxyl groups of YEGDQGAGY and PCHHY provided the main ferrous-chelating sites. Ferrous chelation did not alter the ACE-inhibitory activity of PCHHY and YEGDQGAGY, but reduced their antioxidant activity, especially reducing power (from 0.422 to 0.245). The ACE-inhibitory and antioxidant activities of PCHHY were stable during gastrointestinal digestion. PCHHY and YEGDQGAGY improved ferrous stability during gastrointestinal digestion ( p < 0.05). YEGDQGAGY and PCHHY have the potential to prevent oxidative stress, hypertension, and iron deficiency. Future studies should focus the in vivo functionalities. • PCHHY and YEGDQGAGY showed ACE-inhibitory, iron binding and anti-oxidant abilities. • YEGDQGAGY and PCHHY bind to 13 and 3 key sites of ACE by short hydrogen bonds. • Amino and carboxyl groups of YEGDQGAGY and PCHHY were the main iron binding sites. • YEGDQGAGY and PCHHY enhanced ferrous stability during gastrointestinal digestion. • Ferrous chelation reduced the anti-oxidant activity of YEGDQGAGY and PCHHY.