After being treated with protease K, peptides extracted from donkey blood were separated, identified, and characterized. The results showed that Sephadex G-25 medium purified with MW < 3 kDa had the highest dipeptidyl peptidase IV (DPP-IV) inhibition capacity. Three-hundred-and-thirty-four peptides were identified with UPLC–MS/MS. Peptide Ranker and molecular docking analysis were used to screen active peptides, and 16 peptides were finalized out of the 334. The results showed that the lowest binding energy between P7(YPWTQ) and DPP-IV was −9.1, and the second-lowest binding energy between P1(VDPENFRLL) and DPP-IV was −8.7. The active peptides(MW < 3 kDa) could cause a reduction in the fasting blood glucose levels of type 2 diabetic mice, improve glucose tolerance, and facilitate healing of the damaged structure of diabetic murine liver and pancreas. Meanwhile, the peptides were found to ameliorate the diabetic murine intestinal micro-ecological environment to a certain extent.

Background: Oxidative stress and inflammation are major drivers of metabolic inflammatory diseases, and natural antioxidant peptides represent promising therapeutic agents. Antioxidant peptides derived from Cyperus protein (CAOP) exhibit high digestibility and bioavailability, but their antioxidant and anti-inflammatory mechanisms remain unclear. Methods: We employed in vitro experiments, non-targeted metabolomics, peptide omics, and molecular docking techniques to explore how CAOP exerts dual antioxidant and anti-inflammatory effects. Results: The in vitro experiments showed that in LPS-induced RAW264.7 cells, CAOP not only significantly increased the levels of superoxide dismutase (SOD) and catalase (CAT) but also significantly reduced the gene expression and secretion of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), as well as the phagocytic ability of cells. Metabolomics studies indicate that CAOP protects cells from LPS-induced damage by enhancing intracellular glutathione metabolism pathways, glyceraldehyde and dicarboxylic acid metabolism pathways, pantothenic acid and coenzyme A biosynthesis metabolism pathways, and thiamine metabolism pathways while inhibiting the ferroptosis pathway. CAOP was purified using Sephadex G-25 column chromatography, and its amino acid sequence was determined using LC-MS/MS technology. Subsequently, 25 peptide sequences were screened through bioinformatics analysis. These peptides can target Keap1. Among them, DLHMFVWS (-ICE = 62.8072) and LGHPWGNAPG (-ICE = 57.4345) are most likely to activate the Nrf2-Keap1 pathway. Conclusions: CAOP exerts antioxidant and anti-inflammatory effects by regulating the key metabolic networks, demonstrating its therapeutic promise for associated with oxidative damage and metabolic inflammation disorders.