Gastric-protective and antioxidant effects of fermented Pichia pastoris residue hydrolyzed peptides on alcohol-treated mice.

Alcoholic gastric ulcer is a prevalent digestive disorder closely associated with oxidative stress and inflammatory damage, prompting growing interest in bioactive peptides as potential nutritional interventions. This study aimed to evaluate the nutritional composition, in vitro antioxidant activity, and gastroprotective effects of Pichia pastoris residue hydrolyzed peptides (PPRHP) in a mouse model of ethanol-induced gastric injury. Amino acid analysis revealed that PPRHP contains 17 amino acids with an essential-to-total amino acid ratio of 0.512. In vitro assays demonstrated strong radical (ABTS and hydroxyl) and hydrogen peroxide scavenging abilities, as well as copper ion chelation capacity, attributable to the reactive residues within the peptide sequences like histidine, tyrosine, and methionine. In vivo, pretreatment with PPRHP (200, 400, and 800 mg/kg) dose-dependently ameliorated ethanol-induced gastric damage, as evidenced by reduced ulcer area, submucosal edema, and leukocyte infiltration. Furthermore, PPRHP significantly reversed oxidative stress by elevating gastric superoxide dismutase and serum catalase levels while reducing gastric malondialdehyde and myeloperoxidase levels (p < 0.001), with the most pronounced effects observed at the medium dose of 400 mg/kg. These findings indicate that PPRHP, a peptide-rich and antioxidant substance, exerts significant protective effects against ethanol-induced gastric ulcers, likely through mechanisms involving free radical scavenging, metal ion chelation, inhibition of lipid peroxidation, and restoration of oxidative-antioxidative balance.