Antioxidative stress activity of oligophosphopeptides derived from hen egg yolk phosvitin in Caco-2 cells

The protective effects of hen egg yolk phosvitin phosphopeptides (PPPs) against hydrogen peroxide (H2O2)-induced oxidative stress were evaluated in an in vitro assay using human intestinal epithelial cells. Caco-2 cells were stimulated with 1 mM H2O2 for 6 h, and the secretion of IL-8, a proinflammatory mediator, was determined by ELISA as a biomarker of oxidative stress. The inhibition of H2O2-induced IL-8 secretion from Caco-2 cells was observed by pretreatment for 2 h with PPPs, but not with phosvitin. PPPs also suppressed the formation of malondialdehyde in H2O2-treated Caco-2 cells. Furthermore, intracellular glutathione levels and glutathione reductase activity were elevated by the addition of PPPs. The protective effects of PPPs against H2O2-induced oxidative stress were almost the same as that of glutathione, and PPPs with a high content of phosphorus exhibited higher protective activity than PPPs without phosphorus; however, phosphoserine itself did not show any significant antioxidative stress activity. These findings suggest that oligophosphopeptides from hen egg yolk phosvitin possess novel antioxidative activity against oxidative stress in intestinal epithelial cells and that phosphorus and peptide structure seem to have a key role in the activity.