Angiotensin I Converting Enzyme Inhibitoiy Effects of Gelatin Hydnolysates Prepared from Tilapia mossambica Scales by Hot Water and Enzymatic Extraction

摘要

Fish scales have potential in functional food preparation due to their antioxidant and antihypertensive properties. We investigated the angiotensin I converting enzyme (ACE) inhibitory activity of Tilapia mossambica scale extracts. Hydrolysates of tilapia scales were prepared by enzymatic extraction using five proteases (alpha -chymotrypsin, Alcalase, Kojizyme, Protamex and trypsin) after scales were treated with hot water for 3 hr. Scale enzymatic hydrolysates prepared using both hot water and enzyme treatments exhibited elevated hydrolysis (about 25%~55%) compared to only enzyme treatment (about 15%-45%). Enzymatic hydrolysates (1 mg/mL) prepared by both hot water and enzyme treatments also showed significantly increased ACE inhibitory activitiesfrom about 20%-75%. The pattern of ACE inhibitory activities was similar to the degree of hydrolysis. Alcalase and a -chymotrypsin hydrolysates displayed the highest ACE inhibitory activities (IC_(50) = 0.83 mg/mL and 0.68 mg/mL, respectively). In addition, the ACE inhibitory effects of a -chymotrypsin hydrolysates increased with decreasing molecular weight (5 kDa>, 10 kDa> and 30 kDa>), with the 5 kDa> fraction displaying the highest ACE inhibitory activity (about 89.9% and IC_(50) = 0.1 mg/mL). We suggest that the peptide compounds of enzymatic hydrolysates prepared from tilapia scale enhances ACE inhibitory activity and might be useful as an antihypertensive material.