Effect of ultrasound pretreatment on the antioxidant capacity and antihypertensive activity of bioactive peptides obtained from the protein hydrolysates of Erythrina edulis

The aim of this research was to evaluate the effect of ultrasound pretreatment on enzymatic hydrolysis with Flavourzyme (R) and Alcalase (R) enzymes and the ACE-inhibitory activity and the antioxidant capacity of protein hydrolysates of Erythrina edulis. A protein concentration of 78.8% was obtained after sonicating the protein solutions (10%, w/v) for 10 min at 80 kHz and 100% amplitude. The ultrasonic pretreatment (UP) increased the degree of hydrolysis (47.7%) up to 70 min, the IC50 values in both samples [with (UP) and without pretreatment (WP)] were 100 mu g/mL, and the UP samples presented the highest percentage of inhibition at 57.3%. The UP hydrolysates showed the highest (p < 0.05) antioxidant (ABTS*) and radical (DPPH*) - scavenging activities, with IC50, values ranging from 64.52 to 77.62 mu g/mL and from 151.13 to 173.22 mu g/mL, respectively. In SDS-PAGE, the hydrolysates UP exhibited low molecular weight bands (8 - 20 kDa). The results of both, antioxidants and antihypertensive activities obtained in vitro, showed a higher percentage of activity for the peptides obtained after pretreatment with ultrasound than for those obtained without the use of ultrasound prior to enzymatic hydrolysis.