Identification of four new angiotensin I-converting enzyme inhibitory peptides from fermented anchovy sauce

The inhibitory activity of an angiotensin I-converting enzyme (ACE), a key regulatory enzyme of blood pressure from the fermented anchovy sauce, was evaluated, and ACE inhibitory peptides were purified. The ACE activity significantly increased with an increase in salt concentration. In addition, the ACE inhibitory activity of the fermented anchovy sauce containing high salt content (25 %) significantly increased with an increase in fermentation time. The maximum activity (96 %) was reached after 15 months of fermentation. Four ACE inhibitors [Pro-Lys (PK), Gly-Cys-Lys (GCK), Asn- His-Pro (NHP), and Asp-Gly-Gly-Pro (DGGP)] in the fermented anchovy sauce were purified through various chromatographic techniques and identified by electrospray ionization tandem mass spectrometer analysis. Four newly identified peptides were synthesized and analyzed for ACE inhibitory activity in order to confirm that the purified peptides were actually ACE inhibitors. The IC50 values for ACE inhibitory activities of synthesized peptides DGGP, GCK, NHP, and PK were 164, 178, 1172, and 4092 μM, respectively.