Antioxidant Peptide Fractions Isolated from Wheat Germ Protein with Subcritical Water Extraction and Its Transport Across Caco-2 Cells.

Wheat germ protein (WGP) was extracted with subcritical water and then hydrolyzed with Alcalase 2.4 L to obtain antioxidant hydrolysates. Wheat germ peptides (WG-P, Mw < 1 kDa) were purified by using Sephadex G-15 column chromatography. The results showed that WG-P-4 possessed the strongest DPPH radical scavenging activity in comparison with other peptides fractions. In addition, free amino acids and LC-MS/MS analysis showed that Gly-Pro-Phe, Gly-Pro-Glu, and Phe-Gly-Glu were the major peptides of WG-P-4. Interestingly, the WG-P-4 fractions had good absorption characteristic. Moreover, the ratio of P both sides of apical compartment (AP) and basolateral compartment (BL) were between 0.5 and 1.0 on Caco-2 cell model, which indicated that transmembrane transportation was mainly passive transport. Therefore, WG-P could exert an effective antioxidant action by across the intestinal epithelium.