Antioxidant Capacity and Angiotensin-I Converting Enzyme (ACE)-Inhibitory Activities of Peptide Fractions Obtained from Triggerfish (Balistes capriscus) Co-products

The fish industry can generate a significant amount of waste that has economic potential for use in the pharmaceutical and food industries. The aim of this study was to evaluate the antioxidant and ACE-inhibitory activities of peptide fractions from triggerfish (Balistes capriscus) processing coproducts. Protein fractions were extracted from fish viscera and hydrolyzed using papain (HP), bromelain (HB), and trypsin (HT) (3% p.p(-1), 6 h). The molecular mass distribution of soluble protein extract (SPE) and hydrolysate was determined by gel filtration chromatography. Samples were extracted and ultra-filtrated (> 100 MWCO, 30-100, 10-30 and < 10 MWCO). Antioxidant activity of fractions was evaluated, and fraction SPE4 (< 10 MWCO) showed the highest value of Trolox Equivalent Antioxidant Capacity-TEAC (10,157.7 mu mol Trolox. g(-1)) and Ferric Reducing Antioxidant Power-FRAP (1588.71 mu mol FeSO4. g(-1)). SPE and hydrolysates (< 10 MWCO) were distributed into fractions by ion-exchange chromatography and subjected to antioxidant activity assays. F1 fraction showed the highest value for TEAC capacity (8839.04 <mu>mol Trolox. g(-1)) and FRAP (1749.94 mu mol FeSO4. g(-1)). ACE-inhibitory activity was evaluated for SPE and hydrolysate and fractions F3, F5, and HP3 showed the lowest IC50 values (30.1, 42.7 e 37.7 mu g, respectively). Amino acid sequencing of peptides indicated the presence of hydrophobic amino acids such as leucine (L), valine (V), phenylalanine (F), and alanine (A) in the C-terminal position, which contributed to antioxidant activity of peptides fractions. ACE inhibitory capacity was influenced by the presence of arginine (R) and lysine (K) positively charged in the C-terminal. Protein extracted from triggerfish viscera is a good source of bioactive peptides that can be used in the pharmaceutical and food industries.