Separation and Purification of Small Peptides from Fermented Sesame Meal and Their Antioxidant Activities

Protein hydrolysates are widely applied as antioxidants in nutrition, but the potential antioxidant activities of small peptides remain unknown. Therefore, we investigated the antioxidant activities of small peptides isolated from solid-state fermented sesame meal via Sephadex G-15 chromotography. The scavenging capacities for 2, 2- diphenylpicrylhydrazyl (DPPH) and hydroxyl (•OH) radicals as well as the total reducing capacity were determined. The in vivo antioxidant activity was determined upon 30-d intragastric administration of the isolated small peptides (tripeptide, tetrapeptide, and hexapeptide) at different doses (0.1, 0.2, and 0.4 g/kg•d) in healthy Kunming mice. The results showed that the DPPH and •OH scavenging rates of the three peptides exceeded 80%. The total reducing activities of 4 mg/mL tetrapeptide or hexapeptide and 2 mg/mL tripeptide were comparable to that of 0.5 mg/mL glutathione. In mice fed sesame peptides, malondialdehyde levels in the serum and liver were lower than those in controls, whereas the activities of liver superoxide dismutase and glutathione peroxidase were significantly higher than those in controls (P<0.05). The antioxidant activity of tripeptide was significantly higher than those of tetrapeptide and hexapeptide (P<0.05). In conclusion, small peptides extracted from solid-state fermented sesame meal possess strong antioxidant activities that increase with decreasing peptide molecular weight.