Abstract: To develop natural, low-toxicity functional food ingredients, this study prepared wheat peptides from gluten powder by enzymatic hydrolysis. The physicochemical properties and stability of the peptides were analyzed, their effects on the viability of human hepatoma cells (HepG2) were investigated, and their alleviating effects and underlying mechanisms on alcohol-induced liver cell injury were explored. The results showed that the proportion of wheat peptide components with a molecular mass below 1 000 Da was 92.883 2%, the acid-soluble protein content reached (87.23 ± 1.76)%, and the relative content of essential amino acid was (22.70 ± 0.54)%. The wheat peptides exhibited good stability under acidic, alkaline, high-temperature, and in vitro simulated digestion conditions. Cell experiments indicated that the wheat peptides at mass concentrations of 0.25–6 mg/mL were non-toxic to HepG2 cells. It was also found that the wheat peptides at mass concentrations of 2−6 mg/mL significantly reduced oxygen species (ROS) and malondialdehyde (MDA) levels in ethanol-induced HepG2 cells (P < 0.05), increased superoxide dismutase (SOD) and catalase (CAT) activities as well as glutathione (GSH) content (P < 0.05), and simultaneously inhibited the release of inflammatory factors such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), thereby alleviating alcohol-induced liver cell injury. Western blot results demonstrated that the wheat peptides activated nuclear factor erythroid 2-related factor 2 (Nrf2), up-regulated heme oxygenase-1 (HO-1) expression, and suppressed Kelch-like ECH-associated protein 1 (Keap1) expression, indicating that they can ameliorate alcoholic liver injury by activating the Nrf2-Keap1-HO-1 signaling pathway.

Key words: wheat peptides; antioxidant activity; alcoholic liver disease; nuclear factor-erythroid 2-related factor 2-Kelch-like ECH-associated protein 1-heme oxygenase-1 signaling pathway