Resumo

CORREA-HERNANDEZ, Sofía Ximena et al. Vasodilator profile of flavonoid and phenylbutanoid compounds isolated from Croton schiedeanus Schlecht. rev.fac.med. [online]. 2008, vol.56, n.4, pp.291-301. ISSN 0120-0011.

Background. Croton schiedeanus Schlecht (Euphorbiaceae), specie is used in Colombian folk medicine in hypertension treatment. Objective. To assess the vasorelaxant effect of the flavonoid compounds: 3-O-methyl-quercetin, 3,7-di-O-methylquercetin, and 3,3',4',7-tetra-O-methylquercetin, and the phenylbutanoids compounds: (2S)-7,9-dimethoxyrhododendrol, (2S)-2-acetoxy-7,9-dimetho-xyrho-dodendrol, (2S)-2,8-diacetatoxy-7,9-dimethoxyrho-dodendrol in isolated aortic rings of Wistar rats. Materials and methods. These compounds were evaluated in phenylephrine (PE, 1 µM) and KCl (80 mM) precontracted aortic rings. In order to examine possible interactions related with: endothelium, nitric oxide (NO), guanylyl ciclasa, prostanoid or ATP dependent potassium (K+ATP) channels, the compounds with greater relaxant effect: 3-O-methylquercetin, and 3,7-di-O-methylquer-cetin, were assessed in phenylephrine precontracted rings in presence or absence of: endothelium, L-NAME (G -nitro-L-Arginine-Methyl Ester, 100 µM), ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, 1 µM), sodium meclofenamate (10 µM) or glibenclamide (1 µM). Results. Whereas phenylbutanoid compounds did not shown significant relaxant properties, 3-O-methylquercetin and 3,7-di-O-methyl-quercetin displayed important vasodilator responses with IC50 of 2.5 and 4.9 µM against phenylephrine respectively. ODQ and L-NAME effectively displaced to the right the dose-response curves of these compounds, especially in the case of 3-O-methylquercetin (IC50 ratio: 7.4 and 3.8) whereas glibenclamide did not and meclofenamate only slightly. Conclusion. 3-O-methylquercetin and 3,7-di-O-methylquercetin, flavonoid compounds isolated from Croton schiedeanus play important vasorelaxant effects related to the NO/cyclic GMP pathway. These results support the etnobotanical use of Croton schiedeanus.

Palavras-chave : Euphorbiaceae; Rhododendrol; 3-O-Methylquercetin; 3,7-Di-O-methylquer-cetin; Nitric Oxide; vasodilator Agents.

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