Purification and identification of antioxidative peptides of palm kernel expeller glutelin-1 hydrolysates

Abstract

To obtain hydrolysates with high antioxidant activity and hydrolysis degree, palm kernel expeller glutelin-1 was hydrolyzed by pepsin assisted with high pressure pretreatment. The results of orthogonal experiment revealed that the optimum enzymatic hydrolysis conditions were as follows: enzymes concentration of 2 g/100 g, hydrolysis time of 4 h, temperature 37 °C and pH 2.0. Palm kernel expeller glutelin-1 hydrolysate was separated by ultrafiltration, Sephadex G-15 gel chromatography and reversed-phase high performance liquid chromatography. Finally, four peptides Thr-Val-Phe-Asp-Gly-Glu-Leu-Arg (935.5 Da), Ala-Asp-Val-Phe-Asn-Pro-Arg (818.7 Da), Cys-Ala-Gly-Val-Ser-Ala-Ile-Arg (832.4 Da) and Leu-Val-Tyr-Ile-Ile-Gln-Gly-Arg (819.4 Da) were identified and their IC₅₀ values on hydroxyl radical scavenging activities were 38.22 ± 2.22, 22.16 ± 1.22, 31.19 ± 1.67 and 12.85 ± 0.23 μg mL⁻¹, respectively. Furthermore, these peptides were chemically synthesized and the peptides ADVFNPR and CAGVSAIR showed good stability against simulated gastrointestinal protease digestion.