Vascular Effects, Angiotensin I-Converting Enzyme (ACE)-Inhibitory Activity, and Antihypertensive Properties of Peptides Derived from Egg White (original) (raw)

2007, Journal of Agricultural and Food Chemistry

In this study, we have identified novel antihypertensive peptides derived from egg-white proteins. The sequences YRGGLEPINF and ESIINF produced an acute blood-pressure-lowering effect in spontaneously hypertensive rats upon a single oral administration. Our results suggest that the antihypertensive action could be attributed to a vascular-relaxing mechanism that would occur in vivo independently of angiotensin I-converting enzyme (ACE) inhibition, because neither these peptides nor their main digestion fragments, except for the dipeptide YR, acted as ACE inhibitors in vitro. The vasodilator and antihypertensive activity of the sequences ESI and NF would explain the bloodpressure-lowering effect of ESIINF. With regard to YRGGLEPINF, in addition to NF, YR appeared as the main fragment responsible for its activity. The dipeptide YR, named kyotorphin and previously identified as an endogenous analgesic neuropeptide in the central nervous system, showed strong vasodilator and antihypertensive properties. The structure-activity features of the vasodilator peptides are discussed. DGSRQPV (ovotransferrin 230-236). The fragments resulting from the simulation of the gastrointestinal digestion of YRGGLEPINF and ESIINF (YRGGLEPI, YR, GGLEPI, ESI, and NF) were also synthesized. All of these peptides were obtained by conventional Fmoc solid-phase synthesis with a 431A peptide synthesizer (Applied Biosystem, Inc., Ü berlingen, Germany) according to the method described by Atherton and Sheppard (29). They were synthesized and provided by the Unitat de Pèptids of Barcelona University, and their purity (>90%) was verified in our laboratory by reversed-phase high-performance liquid chromatography-tandem mass spectrometry (RP-HPLC-MS/MS) (30). The drugs and the peptides were dissolved in distilled water for the reactivity experiments and administration to the rats.