Antioxidant and angiotensin-I converting enzyme inhibitory peptides from Hippocampus abdominalis

Bioactive peptides isolated from edible marine sources have been used as nutraceuticals and functional foods. The present study focuses on the alcalase hydrolysate of Hippocampus abdominalis for the isolation of antioxidative and angiotensin-I converting enzyme (ACE) inhibitory peptides. Initially, the H. abdominalis alcalase hydrolysate (HA) was separated using ultrafiltration (MWCO=5kDa), and have obtained the fraction, HA-III (MW5kDa), with strong bioactivity. This was further separated using gel filtration chromatography (Sephadex G-10) and reverse-phase high-performance liquid chromatography (RP-HPLC). The active Sephadex G-10 fraction was analyzed by the Q-TOF mass spectrometry, nine peptides were identified within the molecular mass range between 757.8 and 990.1Da. Three peptides, GIIGPSGSP, IGTGIPGIW, and QIGFIW, showed strong ACE inhibitory activity and alkyl radical-scavenging activity. Molecular docking studies revealed that the ACE inhibitory activity of the three active peptides is mainly due to hydrogen bonding interactions and active site interactions between active peptides and ACE. This study demonstrated that the active peptides derived from H. abdominalis can be isolated and the proteolytic hydrolysates of it are potential antioxidant and antihypertensive agents.