Determination of endogenous peptides with in vitro ACE inhibitory activity in normotensive human plasma by the fluorometric HPLC method

An in vitro degradation test of angiotensin (ANG) II or III in normotensive supine human plasma from 9 healthy male subjects confirmed the production of smaller ANG metabolites with angiotensin I-converting enzyme inhibitory activity. These metabolites were identified as ANG (3–8), ANG (4–8), ANG (5–8), and ANG (3–4), whose respective peptide concentrations were determined by our proposed naphthalene-2, 3-dialdehyde (NDA)-HPLC method to be 64 ±9, 39 ±5, 176 ± 22, and 197 ± 35 fmol/ml of plasma. Pediococcus sp. ISK-1 isolated in our laboratory from well-aged Nukadoko, produces a bacteriocin which has a unique antimicrobial spectrum among pediocins. The bacteriocin was stable at acidic pH, and more than 60% of the antimicrobial activity still remained even after being autoclaved at 121°C for 20min in the pH range of 3 to 8. This is the first report dealing with a bacteriocin produced by lactic acid bacteria isolated from Nukadoko.