Functional and potential therapeutic ACE-inhibitory peptides derived from bromelain hydrolysis of trevally proteins

In a view to produce physiologically active peptides, soluble and insoluble fish protein fractions from trevally (Pseudocaranx sp.) were hydrolysed with bromelain and the hydrolysates were used in a systematic screening for angiotensin I-converting enzyme (ACE)-inhibitory peptides. The IC50 values of hydrolysates from soluble protein substrate ranged from 1.99 to 3.34 mg/mL, while the values for hydrolysates from insoluble protein substrate ranged from 2.45 to 4.74 mg/mL. Fractionation with RP-HPLC gave three most active peptide fractions labelled as TBS1, TBS2, and TBI2 which showed high potential as ACE-inhibitory agents. The primary structures of the three stable and active peptide fractions are AR, AV, and APER, with molecular weights of 245.28, 188.23, and 471.51 Da, respectively. Simulated gastrointestinal enzyme degradation of the three selected peptide fractions revealed their stability in the gut. In addition the <5 kDa fractions derived from the hydrolysates labelled TSB6h and TIB2h have potential to be used in functional foods.