Thermoase-derived flaxseed protein hydrolysates and membrane ultrafiltration peptide fractions have systolic blood pressure-lowering effects in spontaneously hypertensive rats.

Ifeanyi Nwachukwu,Sunday Malomo,Rotimi Aluko,John Onuh,Abraham Girgih

doi:10.3390/ijms151018131

Ifeanyi Nwachukwu, Sunday Malomo + Show 3 more

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https://doi.org/10.3390/ijms151018131

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Abstract

Thermoase-digested flaxseed protein hydrolysate (FPH) samples and ultrafiltration membrane-separated peptide fractions were initially evaluated for in vitro inhibition of angiotensin I-converting enzyme (ACE) and renin activities. The two most active FPH samples and their corresponding peptide fractions were subsequently tested for in vivo antihypertensive activity in spontaneously hypertensive rats (SHR). The FPH produced with 3% thermoase digestion showed the highest ACE- and renin-inhibitory activities. Whereas membrane ultrafiltration resulted in significant (p < 0.05) increases in ACE inhibition by the <1 and 1–3 kDa peptides, only a marginal improvement in renin-inhibitory activity was observed for virtually all the samples after membrane ultrafiltration. The FPH samples and membrane fractions were also effective in lowering systolic blood pressure (SBP) in SHR with the largest effect occurring after oral administration (200 mg/kg body weight) of the 1–3 kDa peptide fraction of the 2.5% FPH and the 3–5 kDa fraction of the 3% FPH. Such potent SBP-lowering capacity indicates the potential of flaxseed protein-derived bioactive peptides as ingredients for the formulation of antihypertensive functional foods and nutraceuticals.

Highlights

Hypertension is a major risk factor for cardiac, cerebrovascular and other vascular diseases [1], it is considered a leading cause of mortality worldwide with over 7 million deaths and 92 million disability-adjusted life years recorded annually [2]
The highest inhibitory value of 87% was recorded for the flaxseed protein hydrolysates (FPH) sample obtained at the 3% thermoase concentration and this level of angiotensin I-converting enzyme (ACE) inhibition was significantly (p < 0.05) higher than the values obtained for all the other protein hydrolysate samples
1% to 1.5% resulted in statistically significant differences in the percentage of ACE inhibition, neither increasing the enzyme concentration from 1.5% to 2%, nor from 2% to 2.5% produced any difference in ACE inhibition of statistical significance

Summary

Introduction

Hypertension is a major risk factor for cardiac, cerebrovascular and other vascular diseases [1], it is considered a leading cause of mortality worldwide with over 7 million deaths and 92 million disability-adjusted life years recorded annually [2]. The renin-angiotensin-aldosterone system (RAAS), which is an important signaling pathway credited with the regulation of extracellular fluid volume, arterial pressure, and tissue perfusion has received significant attention from investigators recently because of its potential as an excellent target for blood pressure lowering agents [3,4,5,6]. Safer antihypertensive agents with the capacity to modulate multiple blood regulation pathways are urgently needed. Given the oft-touted safety of bioactive compounds of biogenic origin in contradistinction to chemically synthesized agents (drugs), various investigators [6,9,10,11,12] have explored the possibility of developing safer but effective antihypertensive agents from animal and plant food proteins in the last few years

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