• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.5
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• pp.426-433
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• 2009

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 activities from about 20%-75%. The pattern of ACE inhibitory activities was similar to the degree of hydrolysis. Alcalase and ${\alpha}$-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 $IC_{50}$-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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.5
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• pp.417-425
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• 2009

The potential utility of fish scales to the functional food industry has been investigated due to its antioxidant and antihypertensive characteristics. In this study, we report on the reactive oxygen species (ROS) scavenging and angiotensin I converting enzyme (ACE) inhibitory activities of gelatin hydrolysates processed from Branchiostegus japonicus scales, which are also high in protein content (about 46.1%). We prepared the enzymatic gelatin hydrolysates with four proteases (${\alpha}$-chymotrypsin, Alcalase, Neutrase and trypsin) from B. japonicus scale gelatin, which was prepared according to different reaction times, substrate/enzyme ratios and substrate concentrations. The enzymatic hydrolytic degrees of the gelatin increased time-dependently up to 6 hrs, while the Alcalase gelatin hydrolysates showed the highest hydrolysis degrees compared to the others. Furthermore, gelatin hydrolysates of Neutrase and ${\alpha}$-chymotrypsin showed the highest DPPH radical and $H_2O_2$ scavenging activities ($IC_{50}$ value; 9.18 mg/mL and 9.74 mg/mL), respectively. However, the activities were not significant (P<0.05). We also observed that the four gelatin hydrolysates significantly increased ACE inhibitory activities from approximately 20% to 60% (P<0.05), Among them, the Alcalase gelatin hydrolysates showed the higher ACE inhibitory activity ($IC_{50}$ value; 0.73 mg/mL) compared to the others. These results suggest that the enzymatic gelatin hydrolysates prepared from B. japonicus scales may possess a potentially useful function as an ACE inhibitory agent. As such, the utility of B. japonicus scales should be given due consideration for application in the functional food industry.