Response surface optimization of selenium-enriched Moringa oleifera seed peptides with antioxidant, ACEI and XOI activities

In this study, selenium (Se)-enriched Moringa oleifera ( M . oleifera ) seed protein peptides were prepared from Se-enriched M . oleifera seed protein powder by single-factor experiments and response surface optimization, and the Se content, amino acid composition, antioxidant activity, angiotensin-converting enzyme inhibitory (ACEI) activity and xanthine oxidase inhibitory (XOI) activity were evaluated. The results showed that the optimal enzymatic hydrolysis conditions were as follows: time 1.64 h, temperature 37 °C, pH1, enzyme to substrate ratio (E/S) 0.32%, solid to liquid ratio (S/l) 5%. The Se-enriched M . oleifera seed protein peptides prepared under these conditions were rich in essential amino acids (27.65%) and hydrophobicity amino acids (36.28%), and the Se content was 1.78 times that of M . oleifera seed protein, with good free radical scavenging activity against DPPH (IC 50 = 4.37 mg/ml) and ABTS (IC 50 = 5.45 mg/ml) and excellent cellular antioxidant activity (CAA) against HepG2 cells (EC 50 = 0.221 μg/ml). In addition, the peptides had good ACEI activity (IC 50 = 2.195 mg/ml) and XOI activity (IC 50 = 6.393 mg/ml). This study provides a theoretical basis for the application of Se-enriched M . oleifera seed protein peptides in the development of natural Se-enriched antioxidant, antihypertensive and anti-hyperuricemia functional ingredients.