Novel antioxidant peptides from tiger nut (Cyperus esculentus L.): Isolation, characterization, and cytoprotective functions on HepG2 and Caco-2 cells

The antioxidant activity of the peptides from tiger nut was investigated for the first time. The tiger nut peptides (TNP) were found to perform excellent antioxidant activity supported by their chemical and cell antioxidant behaviors, amino acid composition, and morphological observation. Higher 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and ferric ion reducing antioxidant power were observed in the TNP with more hydrophobic amino acids compared with traditional soybean and peanut peptides. Furthermore, the peptides from tiger nut could effectively protect H ₂ O ₂ -induced HepG2 and Caco-2 cells from oxidative damage by enhancing endogenous antioxidant enzyme activities and reducing oxidative stress levels, especially the T3 peptides purified from the fraction less than 1 kD molecular weight. And increased catalase, superoxide dismutase, and glutathione peroxidase activities, while high intracellular reactive oxygen species and malondialdehyde inhibition occurred. This study could provide a new strategy for the development of promising antioxidant peptides for food applications.