Angiotensin-I Converting Enzyme Inhibitory Activity of Hydrolysates from Oat (Avena sativa) Proteins by In Silico and In Vitro Analyses

The potential for producing anti hypertensive peptides from oat proteins through enzymatic hydrolysis was assessed in silico and confirmed in vitro. Thermolysin (EC 3.4.24.27) was predicted using BIOPEP database as the enzyme that would theoretically produce the most angiotensin I converting enzyme (ACE) inhibitory peptides from oat. Experimental evidence confirmed that strong ACE-inhibitory activity was produced under various hydrolysis conditions. Hydrolysates produced under high enzyme-to-substrate ratio (3%) short time (20 min) (HEST) and low enzyme-to-substrate ratio (0.1%) long time (120 min) (LELT). conditions had IC50 values of 30 and 50 mu g/mL, respectively. After simulated gastrointestinal digestion, the IC50 of the HEST hydrolysate was 35 mu g/mL whereas the IC50 of the LELT hydrolysate was higher at 85 mu g/mL. Ultrafiltration revealed that potent ACE-inhibitory peptides had molecular weights below 3 kDa. This study demonstrates the usefulness of in silico analysis to select enzymes for hydrolysis of proteins not previously examined as sources of bioactive peptides.