Novel ACE inhibitory, antioxidant and α-glucosidase inhibitory peptides identified from fermented rubing cheese through peptidomic and molecular docking

Our previous studies employed the fermented acidified technology to process fermented rubing cheese (FRB) with a self-screened lactic acid bacteria starter. The present study aimed to use the peptidomics approach to identify novel ACEIPs (angiotensin I-converting enzyme inhibitory peptides), AOPs (antioxidant peptides), and α-glucosidase inhibitory peptides from FRB and clarify the molecular interaction mechanism. Water-soluble peptides from FRB had strong ACEI, antioxidant, and α-glucosidase inhibitory activities. LC-MS/MS analyses identified a total of 430 peptides from FRB. Among the identified peptides, six ACEIPs, five AOPs, and five α-glucosidase inhibitory peptides were screened with potential bioactivity via bioinformatics analysis. Their biological activities were evaluated via chemical synthesis and in vitro activity determination. A novel EKVNELSKD demonstrated the strongest ACEI activity (IC50 = 98 μM). Molecular docking suggested that EKVNELSKD formed hydrogen bonds with the S2 (Gln 281 and His513) of ACE. A novel α-glucosidase inhibitor peptide QPHQPLPP (IC50 = 0.821 mg/mL) formed five strong hydrogen bonds with Arg428, Trp710, Asp568, Glu771, and Asn448 in α-glucosidase. Meanwhile, a novel AOP YPFPGPIH (IC50 = 0.402 mg/mL) also showed significant cytoprotective effects against H2O2-induced HepG2 cellular oxidative damage. Furthermore, YPFPGPIH induced antioxidant mechanisms by activating the Keap1-Nrf 2 pathway.