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 Papp 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.