Key Findings:
Modifications to the rennin angiotensin aldosterone system (RAAS) can affect extracellular fluid volume and blood pressure and hence is a target for dietary treatments of hypertension. Renin and angiotensin I converting enzyme (ACE) is important in the RAAS pathway and its activity can be altered by peptides. This experiment generated unique thermoase derived peptides from flax that exhibited systolic blood pressure lowering in a hypertensive animal model. The bioactive peptides showed very high ACE inhibitory activity. This study explored one of the mechanisms by which flaxseed is proving to be a powerful and important hypotensive agent.
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 per cent thermoase digestion showed the highest ACE and rennin inhibitory activities. Whereas membrane ultrafiltration resulted in significant increases in ACE inhibition by the less than1 and 1 to 3 kDa peptides, only a marginal improvement in Rennin 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 per kg body weight) of the 1 to 3 kDa peptide fraction of the 2.5 per cent FPH and the 3 to 5 kDa fraction of the 3 per cent 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. (Authors Abstract)