Navegando por Palavras-chave "Cecropia glaziovii"

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    ACE activity during the hypotension produced by standardized aqueous extract of Cecropia glaziovii Sneth: A comparative study to captopril effects in rats
    (Elsevier B.V., 2007-05-01) Ninahuaman, M. F. M. L.; Souccar, C.; Lapa, A. J.; Lima-Landman, M. T. R.; Universidade Federal de São Paulo (UNIFESP)
    To evaluate the effect of the standardized aqueous extract (AE) of Cecropia glaziovii Sneth on the plasma angiotensin I converting enzyme (ACE-EC 3.4.15. 1) activity, rats were treated with a single dose of AE (1 g/kg, p.o.) or repeatedly (0.5 g/kg/bid, p.o.) for 60 days. Captopril (50 mg/kg, p.o.) was used as positive control on the same animals. the effects on the blood pressure were recorded directly from the femoral artery (single dose), or indirectly by the tail cuff method (repeated doses) in conscious rats. the plasma ACE activity was determined spectrofluorimetrically using Hypuril-Hystidine-Leucine as substrate. the arterial blood pressure, heart rate and plasma ACE activity were not significantly modified within 24 h after a single dose administration of AE. Comparatively, blood pressure in captopril treated rats was reduced by 7-16% and heart rate was increased by 10-20% from 30 min to 24 h after drug administration. ACE activity after captopril presented a dual response: an immediate inhibition peaking at 30 min and a slow reversal to 32% up-regulation after 24 h. To correlate the drug effects upon repeated administration of either compound, normotensive rats were separated in three groups: animals with high ACE (48.8 +/- 2.6 nmol/min/ml), intermediate ACE (39.4 +/- 1.4 nmol/min/ml) and low ACE (23.5 +/- 0.6 nmol/min/ml) activity, significantly different among them. Repeated treatment with AE reduced the mean systolic blood pressure (121.7 +/- 0.5 min Hg) by 20 min Hg after 14 days. the hypotension was reversed upon washout 60 days afterwards. Likely, repeated captopril administration decreased blood pressure by 20mm Hg throughout treatment in all groups. After 30 days treatment with AE (0.5 g/kg/bid, p.o.) the plasma ACE activity was unchanged in any experimental group. After captopril (50 mg/ kg/bid, p.o.) administration the plasma ACE activity was inhibited by 50% within I h treatment but it was up-regulated by 120% after 12 h in all groups. It is concluded that the hypotension produced by prolonged treatment with AE of C. glaziovii is unrelated to ACE inhibition. (C) 2006 Elsevier GmbH. All rights reserved.
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    Antihypertensive effect of a standardized aqueous extract of Cecropia glaziovii Sneth in rats: An in vivo approach to the hypotensive mechanism
    (Elsevier B.V., 2007-05-01) Lima-Landman, M. T. R.; Borges, A. C. R.; Cysneiros, Roberta Monterazzo [UNIFESP]; De Lima, T. C. M.; Souccar, C.; Lapa, A. J.; Universidade Federal de São Paulo (UNIFESP); Universidade Federal de Santa Catarina (UFSC)
    Cecropia glaziovii Sneth is a common tree at the Southeastern Brazilian coast. As many other species of the genus, it shares the reputed folk use to treat heart failure, cough, asthma and bronchitis. the plant has been cultivated under controlled conditions and the 2% aqueous extract (AE) prepared with the dried leaves was standardized by its chemical contents on catechins, flavonoids and procyanidins. the present paper reports the antihypertensive activity of AE and of n-butanol fraction (BuF), an enriched semi-purified butanolic fraction used to isolate the main chemical constituents. Oral administration of AE and BuF induced hypotension in normotensive rats. the effect of AE (0.5 g/ kg/bi, p.o.) was time and dose-dependent peaking at 2-3 weeks after daily administration. BuF was faster but not more active than AE. Both extracts decreased the hypertension of spontaneous hypertensive rats, the hypertension induced in rats by L-NAME treatment and that induced by constriction of one renal artery. the antihypertensive effect was maintained for as long as 60 days of treatment and was reversible upon drug washout at the same rate of its establishment. Acute i.v. administration of BuF to anesthetized rats induced a fast short-lasting hypotension and inhibited the pressor responses to noradrenaline, angiotensin I and angiotensin II by 40%. These results were indirect indications that the hypotension induced by AE is not related to ACE inhibition, increased NO synthesis, or specific blockade of al and ATI receptors. It can be suggested that BuF interferes with the calcium handling mechanisms in smooth muscle cells and neurons. Intravenous injection of five out of nine compounds isolated from BuF produced immediate but short-lasting hypotension that does not correlate with the onset of the hypotension after oral treatment. This finding suggests that they may not be the compounds directly responsible for the delayed and sustained hypotension after per os administration of AE. the many compounds isolated from AE are under evaluation to determine its pharmacokinetics, mechanisms of action and interactions necessary to yield the plant effect. Although its mechanism is still unknown, AE seems to be an effective and safe anti hypertensive phytomedicine. (C) 2007 Elsevier GmbH. All rights reserved.