Oat Bran Hydrolysates Alleviate Oxidative Stress and Inflammation in <sc>d</sc>-Galactose-Induced Aging Mice

Oat bran hydrolysates exhibit various biological activities, including antioxidant and immunomodulation activities. Enzymatic hydrolysis can improve the antioxidant capacity of oat bran protein. In this study, Alcalase was used to hydrolyze oat bran protein and the resulting hydrolysates were separated by ultrafiltration, the antioxidant activity of fraction F1 (molecular weight > 10 kDa, OBH) was the highest in the four fractions, and selected for exploring the functional characteristics: d-galactose (d-gal; 300 mg/kg/day) induced aging of CL57BL/6J mice and OBH (200, 400, 800 mg/kg/day) intervened for 8 weeks. Normal mice were compared with aging mice induced by d-gal and aged mice treated with OBH. OBH intervention significantly improved the antioxidant oxidase activities in aging mice, such as total antioxidant capacity, catalase and glutathione peroxidase activities; it decreased malondialdehyde levels, and reduced the levels of tumor necrosis factor-alpha, interleukin (IL)-1 beta and IL-6 in the brain and serum. Pathological observations showed that OBH prevented brain damage. The results of high-throughput sequencing showed that the relative abundance of Verrucomicrobiota was decreased, whereas Duncaniella, Paramuribaculum, Odoribacter, and Alistipes_A were increased. Metabolomics analysis showed that OBH mainly altered glycerophospholipid, cysteine and methionine metabolism. These results indicated that OBH has great potential as a functional food, which can alleviate oxidative damage and inflammation in the serum and brain, maintain the stability of intestinal bacteria, alleviate metabolic disorders and delay aging.