Structural Analysis of a New Anti-Hypertensive Peptide (β-Lactosin B) Isolated from a Commercial Whey Product

Abstract Angiotensin-converting enzyme (ACE) inhibitory activities and anti-hypertensive activities in spontaneously hypertensive rats (SHR) of 12 kinds of commercial peptides of food additive grade were measured. Four peptide products derived from milk proteins showed strong anti-hypertensive activities (>−18.0mm Hg). A sample of WE80BG derived from whey proteins showed the strongest anti-hypertensive activity (−21.2±16.9mm Hg) with a medium level of ACE inhibitory activity (53.6%), and it was subjected to hydrophobic and gel filtration chromatography. From the low molecular weight fraction, an anti-hypertensive peptide was isolated by using reversed-phase HPLC, and it was found to be a tetrapeptide, alanine-leucine-proline-methionine (Ala-Leu-Pro-Met, ALPM), the origin of which was estimated to be β -lactoglobulin f 142 to 145. At 8h after oral administration of ALPM in SHR, systolic blood pressure was significantly decreased (−21.4±7.8mm Hg), but the IC 50 value (concentration of peptide needed to inhibit 50% of the ACE activity) of ALPM was not so high. We named the Ala-Leu-Pro-Met " β -lactosin B." This peptide is the second anti-hypertensive peptide found from β -lactoglobulin. Because WE80BG containing ALPM was also found to show the strongest anti-hypertensive activity (−24.5±10mm Hg) at 8h after oral administration in SHR, WE80BG would be suitable for application to the development of a new food expected to have anti-hypertensive effects.