Production of the Blood Pressure Lowing Peptides from Brown Alga ( Undaria pinnatifida )

Brown alga (Undaria pinnatifida) was treated with alginate lyase and hydrolyzed using 17 kinds of proteases andthe inhibitory activity of the hydrolysates for the angiotensin-I-converting enzyme (ACE) was measured. Four hydrolysateswith potent ACE-inhibitory activity were administered singly and orally to spontaneously hypertensive rats (SHRs). The sys-tolic blood pressure of SHRs decreases significantly after single oral administration of the brown alga hydrolysates by pro-tease S 'Amano' (from Bacillus stearothermophilus) at the concentration of 10 (mg protein) (kg body weight)-1. In the 17weeks of feeding experiment, 7-week-old SHRs were fed standard diet supplemented with the brown alga hydrolysates for 10weeks. In SHRs fed 1.0 and 0.1% brown alga hydrolysates, elevating of systolic bloodpressure was significantly suppressedfor 7 weeks. To elucidate the active components, the brown alga hydrolysates were fractionated by 1-butanol extraction andHPLC on a reverse-phase column. Seven kinds of ACE-inhibitory peptides were isolated and identified by amino acid compo-sition analysis, sequence analysis, and LC-MS with the results Val-Tyr, Ile-Tyr, Ala-Trp, Phe-Tyr, Val-Trp, Ile-Trp, andLeu-Trp. Each peptide was determined to have an antihypertensive effect after a single oral administration in SHRs. Thebrown alga hydrolysates were also confirmed to decrease the blood pressure in humans.