RESUMO
Ethanol extract of the aerial parts of Achyrocline satureioides (Lam.) DC. (Asteraceae) showed a significant, dose dependent, relaxant effect on the smooth muscle of corpus cavernosum strips, obtained from Guinea pig (65.5 +/- 4.1% of relaxation at the dose of 25.0 mg/ml). Bioassay guided fractionation of this extract furnished two flavonoids, quercetin and quercetin 3-methyl ether, with important vasorelaxing effects on the corpus cavernosum strips (79.8 +/- 8.4 and 66.0 +/- 4.8% of relaxation respectively at the dose of 0.075 mg/ml). Two methyl derivatives of quercetin obtained by synthesis, quercetin 3,7,3',4'-tetramethylether and quercetin 3,5,7,3',4'-pentamethylether, showed similar relaxant effects at the dose of 0.075 mg/ml (86.4 +/- 8.5 and 67.31 +/- 1.4% of relaxation respectively). The results show that the ethanol extract of A. satureioides and the assayed compounds exhibit significant vasorelaxing properties. Additionally, it is shown that the number of methyl groups in the quercetin nucleus has no significant influence on the effectiveness of these compounds.
Assuntos
Asteraceae , Flavonoides/farmacologia , Relaxamento Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Fitoterapia , Extratos Vegetais/farmacologia , Vasodilatadores/farmacologia , Animais , Relação Dose-Resposta a Droga , Disfunção Erétil/prevenção & controle , Flavonoides/administração & dosagem , Flavonoides/uso terapêutico , Cobaias , Masculino , Ereção Peniana/efeitos dos fármacos , Piperazinas/farmacologia , Componentes Aéreos da Planta , Extratos Vegetais/administração & dosagem , Extratos Vegetais/uso terapêutico , Purinas , Citrato de Sildenafila , Sulfonas , Vasodilatadores/administração & dosagem , Vasodilatadores/uso terapêuticoRESUMO
Extracts of different polarity from Baccharis trimera, Haplopappus rigidus Huperzia saururus, Maytenus ilicifolia, Satureja parvifolia and Senecio eriophyton were tested for their relaxant activity on smooth muscle using L-phenylephrine precontracted strips of corpus cavernosum obtained from Guinea pigs. Highly significant and dose dependent results were obtained with the dichloromethane extracts of H. saururus (87% of relaxation at the dose of 10 mg/ml), S. parvifolia (95% of relaxation at 2.5 mg/ml) and S. eriophyton (94% of relaxation at 5 mg/ml). Similar effects were observed with the methanol extracts of H. saururus (88% of relaxation at 10 mg/ml) and S. parvifolia (84% of relaxation at 10 mg/ml). These results were comparable to those obtained with the dichloromethane and methanol extracts of the well known Mexican species Turnera diffusa. Moreover, the aqueous extract of H. rigidus and the aqueous and methanol extracts of S. eriophyton were highly effective in a dose dependent manner (more than 90% of relaxation at the dose of 10 mg/ml). Significant results, but with a lower overall relaxant activity (about 70% of relaxation at 10 mg/ml), could also be obtained with the aqueous extract of S. parvifolia and with the dichlormethane and methanol extracts of B. trimera and M. ilicifolia. The positive controls with Sildenafil citrate at doses ranging from 0.35 to 35 microg/ml yielded moderate effects (up to 46% of relaxation at 35 microg/ml). The effects observed in the present study seem to validate the folk medicinal use of the tested plants and open new ways in the search for natural products with vasodilatory effects.