In vitro and in vivo assessment of the antihypertensive activity of comercial hydrolysates from various protein sources. / Avaliação in vitro e in vivo da atividade anti-hipertensiva de hidrolisados comerciais de diversas fontes proteicas.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Angiotensin converting enzyme (ACE) inhibitory peptides present in foods have motivated the interest of many researchers, since there is evidence that the ingestion of these peptides, could aid in the prevention and in the non-medication treatment of hypertension. The anti-hypertensive activity of the peptides has been mainly assessed in relation to their capacity to inhibit the ACE, which has a fundamental role in regulating the blood pressure. In this way, innumerous studies have focused on the production and isolation of peptides with ACE-inhibitory activity from proteins from different food sources, though still little is known about the bioavailability of this peptides. The objectives of the present study were: assess the influence of the gastrointestinal enzymes on the ACEinhibitory activity of protein hydrolysates and the correlation with the anti-hypertensive activity assessed in vivo, and to assess the anti-hypertensive effect and kidney function of hydrolysates from different sources. Commercial hydrolysates from the following protein sources were used: casein (Hyprol 8052), milk whey (Hyprol 3301) and wheat gluten (Hyprol 4137), all provided by Kerry Bio-Science; casein (CE90ACE), milk whey (WE80BG) and soy (SE50BT), donated by DMV International, and hydrolysed collagens of bovine and porcine origins (Gelita South America). The hydrolysed collagens were fractionated in an ultrafiltration system using membranes with cut-offs of 30 to 50 kDa, 5 to 8 kDa and 1 to 2 kDa, obtaining the permeates P1 (PM<30-50 kDa), P2 (PM<5-8 kDa) and P3 (PM<1-2 kDa), respectively. The hydrolysates were physicochemically characterized and analysed for their ACE-inhibitory capacity before and after in vitro gastrointestinal digestion, and for their anti-hypertensive activity in spontaneously hypertensive rats (SHR) via oral. The products presenting the best activity in vivo, were assessed for their influence on the kidney function of the animals and for their prolonged hypotensive effect on the blood pressure of SHR in a chronic experiment. The in vitro gastrointestinal hydrolysis promoted a variable effect on the ACE-inhibitory activity. The higher molecular weight hydrolysates, bovine and porcine collagen hydrolysates, presented a significant increase in the ACE-inhibitory potential. On the other hand a reduction in the ACE-inhibitory potential was observed for the smaller molecular weight hydrolysates, such as the casein (Hyprol 8052 and CE90ACE), milk whey (Hyprol 3301) and soy (SE50BT) hydrolysates. The bovine and porcine collagen hydrolysates and their fractions, both before and after in vitro gastrointestinal digestion, presented lower ACE-inhibitory potential than the other hydrolysates.All the hydrolysates analysed were capable of inducing a significant reduction in blood pressure in the SHR, except for the non-fractionated bovine (BCH) and porcine (PCH) collagen hydrolysates. The milk whey (WE80BG) and casein (CE90ACE) hydrolysates, P1 fractions of bovine and porcine collagen (BCHP1 and PCHP1) and the P3 fraction of the porcine collagen hydrolysate (PCHP3) were the most efficient in reducing the blood pressure in SHR. The chronic oral administration of the hydrolysates WE80BG and BCHP1 induced a progressive, significant reduction in the blood pressure of the SHR, showing a difference of 20.60 mmHg and 10 mmHg, respectively, as compared to the basal pressure. The hydrolysate CE90ACE, which presented one of the best in vivo anti-hypertensive activities, induced a reduction in glomerular filtration by the animals and promoted greater sodium excretion at the post-proximal portion of the kidney duct, probably due to a vasodilatory effect on account of ACE-inhibition. On comparing the in vivo results with the IC50 values, before and after gastrointestinal hydrolysis, no relation was observed between the in vitro ACE-inhibitory efficiency and the in vivo reduction in blood pressure by the commercial protein hydrolysates. In conclusion, the gastrointestinal enzymes exert considerable influence on the anti-hypertensive activity of the commercial protein hydrolysates, and can increase or decrease the in vivo hypotensive effect. Thus the in vitro gastrointestinal digestion of the hydrolisates alone, before the assessment of the ACE-inhibitory potential, is apparently of no advantage in predicting the biological activity of the hydrolysates, since apart from the gastrointestinal digestion other factors and/or mechanisms can also be involved in the decrease in blood pressure produced by the action of the peptides.

ASSUNTO(S)

enzimas conversora de angiotensina antihypertensive activity enzymatic digestion angiotensin-converting enzyme spontaneously hypertensive rat hidrolisados proteicos protein hydrolysates ratos espontaneamente hipertensos digestão enzimatica atividade anti-hipertensiva

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