Production and identification of angiotensin I-converting enzyme (ACE) inhibitory peptides from Mediterranean fish discards

The production of peptides exhibiting Angiotensin I-converting enzyme (ACE)-inhibitory activity from discarded Mediterranean fish species such as sardine, horse mackerel, axillary seabream, bogue and small-spotted catshark was studied. The evolution of the ACE-inhibitory activity with the degree of hydrolysis (DH) of protein hydrolysates was also investigated. Hydrolysates of horse mackerel and small-spotted catshark, both obtained with the simultaneous addition of subtilisin and trypsin, showed the highest antihypertensive activity (IC50 of 279 and 302 µg/mL, respectively). For horse mackerel hydrolysate, fraction B (130-2350 Da) exhibited the highest ACE-inhibitory activity (IC50 = 85 µg/mL). In the case of small-spotted catshark hydrolysate, fraction D (<470 Da) presented the lowest IC50 value (27 µg/mL). In addition, 14 novel ACE-inhibitory peptides were identified in horse mackerel and small-spotted catshark hydrolysates. The peptide VAMPF, identified in fraction D of small-spotted catshark hydrolysate, is one of the most promising peptides according to its low IC50 value obtained by the QSAR-model (IC50 = 0.44 µM).