Antioxidant Peptides Derived from Millet Bran Promote Longevity and Stress Resistance in Caenorhabditis elegans

Millet bran as a by-product of millet grain processing remains a reservoir of active substances. In this study, functional millet bran peptides (MBPE) were obtained from bran proteins after alcalase hydrolysis and ultrafiltration. The activity of MBPE was assessed in vitro and in the model organism Caenorhabditis elegans (C. elegans). In vitro, compared to unhydrolyzed proteins, MBPE significantly enhanced the 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate (ABTS) and hydroxyl radicals scavenging activity, and the scavenging rate of MBPE with 15,000 U/g alcalase reached 42.79 ± 0.31%, 61.38 ± 0.41 and 45.69 ± 0.84%, respectively. In C. elegans, MBPE at 12.5 µg/mL significantly prolonged the lifespan by reducing lipid oxidation, oxidative stress, and lipofuscin levels. Furthermore, MBPE increased the activities of the antioxidant enzymes. Genetic analyses showed that MBPE-mediated longevity was due to a significant increase in the expression of daf-16 and skn-1, which are also involved in xenobiotic and oxidative stress responses. In conclusion, this study found that MBPE had antioxidant and life-prolonging effects, which are important for the development and utilization of millet bran proteins as resources of active ingredients.