Abstract
In this study we evaluated the anti-adrenergic response elicited by ayanin, a flavonoid compound isolated from Croton schiedeanus Schlecht, in the pithed rat, and the inhibitory effect of NO synthase inhibitor N (G)-nitro-L -arginine methyl ester (L -NAME), and its acute toxicity profile in mice. In pithed rats ayanin (5 - 50 mg/kg i. v. ) caused a dose-dependent decrease in the pressor and chronotropic responses induced by intravenous noradrenaline administration (0.25 μg/kg). This anti-adrenergic response was completely abolished by prior treatment with L -NAME (10 mg/kg i.v ) and the inhibitory effect of L -NAME was reversed after intravenous administration of L -arginine (100 mg/kg, i. v. ). No lethal or major toxic effects were observed in mice receiving i. p. administration of ayanin up to a dose of 500 mg/kg. Our findings confirm that ayanin exerts protective cardiovascular effects against the increase in blood pressure and heart rate mainly through a mechanism that depends on the NO/cyclic guanosine monophosphate (cGMP) pathway without acute toxic effects. These results suggest that extracts of Croton schiedeanus , the native south American plant from which ayanin was isolated, might be beneficial in cardiovascular disease.
Key words
Nitric oxide - Ayanin - pithed rat - acute toxicity - flavonoids
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