RESUMO
This study evaluated the solubility profiles of quinoa grain proteins and applied a complete process for the isolation of its main protein fractions, namely: albumins, globulins, prolamins and glutelins, which corresponded to 26.96%, 41.3%, 1.7% and 23.16% of the total protein content, respectively. When these fractions were digested with pepsin followed by pancreatin, the degrees of hydrolysis achieved varied between 26.62% (for unheated globulin fraction) and 38.97% (for unheated glutelin), with casein reached 33.73% hydrolysis. After heating, the globulin hydrolysis degree increased to 34.7%, not significantly differing from casein. These results reflect its good susceptibility to hydrolysis by digestive enzymes, and this observation is reinforced with assays with pepsin, trypsin and chymotrypsin tested separately. Globulins, the largest protein fraction, showed promising results in additional assays regarding the amino acid profile, with limitation only for lysine in relation to the FAO standard, and the potential for releasing bioactive peptides after digestion. Although pepsin-digested globulin inhibited only 5% of ACE activity under the conditions tested, after 24h with the addition of pancreatin, the inhibition was 100%. Antioxidant activity (DPPH assay) also indicated very similar results, when hydrolysis with pepsin was inefficient in releasing antioxidant peptides, while hydrolysis by pancreatin led to 35 times greater results.
RESUMO
BACKGROUND: In recent years, it has been demonstrated the inhibitory effect of some plant species on the angiotensin-converting enzyme and rosmarinic acid is a prominent constituent of these species. HYPOTHESIS/PURPOSE: This study was carried out to verify the effect of rosmarinic acid on blood pressure through inhibitory activity on angiotensin-converting enzyme in rats. STUDY DESIGN: The arterial hypertension was promoted using 2-kidneys 1-clip model in rats. The potential inhibitory rosmarinic acid effect on angiotensin-converting enzyme activity was compared with captopril actions by analyzing in vivo blood pressure dose-response curves to angiotensin I and bradykinin. The in vitro plasma angiotensin-converting enzyme activity was measured by fluorimetry using the substrate Abz-FRK(Dnp)P-OH substrate. In addition, dosages of nitrite/nítrate analysis were carried out. RESULTS: (1) rosmarinic acid caused systolic blood pressure dose-dependent decrease in hypertensive rats; (2) The angiotensin I dose-response curves demonstrated that rosmarinic acid promotes minor changes in systolic blood pressure only in the hypertensive group; (3) The bradykinin dose-response curves showed that both rosmarinic acid and captopril promoted a systolic blood pressure reduction, but only the captopril effect was significant; (4) The angiotensin-converting enzyme activity in rat lung tissue was inhibited by the rosmarinic acid in a dose dependent manner; (5) The analysis of nitrite/nítrate plasma concentrations showed no significant difference among the experimental groups. CONCLUSION: The rosmarinic acid is effective in reducing blood pressure, selectively, only in hypertensive animals. The rosmarinic acid (173µM) promoted almost a 98.96% reduction on angiotensin-converting enzyme activity.
