Antioxidant and Anti-Inflammatory Potential of Peptides Derived from In Vitro Gastrointestinal Digestion of Germinated and Heat-Treated Foxtail Millet (Setaria italica) Proteins

This study aimed at identifying antioxidant and anti-inflammatory peptides derived from the in vitro gastrointestinal digestion of germinated and heated (microwave and boiling) foxtail millet. The protein digest fraction containing low-molecular-weight peptides (<3 kDa) and the most hydrophobic subfraction (F4) abundant in random coil structure were responsible for the bioactivity. Then, seven novel peptides were identified using liquid chromatography with tandem mass spectrometry (LC-MS/MS) from the most potent F4 subfraction derived from boiled germinated millet. All seven synthesized peptides significantly (p < 0.05) reduced reactive oxygen species production and increased glutathione content and superoxide dismutase activity in Caco-2 cells, whereas two peptides (EDDQMDPMAK and QNWDFCEAWEPCF) were superior in inhibiting nitric oxide, tumor necrosis factor-α (reduced to 42.29 and 44.07%, respectively), and interleukin-6 (reduced to 56.59 and 43.45%, respectively) production in a RAW 264.7 cell model. This study is the first to report about the potential role of germinated and heated foxtail millet as a source of dual antioxidant and anti-inflammatory peptides.