Trypsin-hydrolyzed Corn Silk Proteins: Antioxidant Activities, in vitro Gastrointestinal and Thermal Stability, and Hematoprotective Effects

Abstract

The aim of this study was to examine the antioxidant capacity of Trypsin-hydrolyzed corn silk proteins, specifically radical scavenging, ferric reducing and anti-lipid peroxidation activities, as well as stability after heating and simulated gastrointestinal digestion. Among the 1–5-h hydrolysates, the 1-h Trypsin hydrolysate (T1H) was the strongest. T1H exhibited stronger H2O2 [half maximal effective concentration (EC50) = 156.44 µg/mL] and superoxide (EC50 = 0.33 mg/mL) scavenging activities than glutathione, carnosine and N-acetylcysteine. Radical scavenging activities of T1H were heat-stable (25–100°C), although lost by 20–58% after gastrointestinal digestion. Ferric reducing activity of T1H was heat-stable, even enhanced by 20% after gastrointestinal digestion. Lecithin liposome assay found anti-lipid peroxidation activity of T1H resistant to gastrointestinal peptidases. By contrast, 100°C incubation reduced anti-lipid peroxidation activity of 0.5 mg/mL T1H to 3.5-fold lower than that of 25°C incubation. At 30 µg/mL, T1H (3% hemolysis) was stronger than glutathione (32% hemolysis) in protecting human red blood cells. T1H was 1.5-fold more potent than glutathione and carnosine in alleviating lipid peroxidation in the cells. Overall, T1H demonstrated strong, heat-stable radical scavenging activities, besides partial resistance to gastrointestinal peptidases. T1H was also hematoprotective. T1H is a promising antioxidant for the development of functional food ingredients and nutraceuticals.

Keywords

• Hematoprotection
• lipid peroxidation
• protein hydrolysate
• simulated gastrointestinal digestion
• stigma maydis
• thermal stability