Inhibitory Effect of N(G)-Nitro-L-arginine Methyl Ester on the Anti-Adrenergic Response Elicited by Ayanin in the Pithed Rat

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 microg/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.

Quercetin 3,7-dimethyl ether: a vasorelaxant flavonoid isolated from Croton schiedeanus Schlecht

“…In previous work we reported the hypotensive and vasorelaxant eOE ects in rats of Croton schiedeanus Schlecht (Guerrero et al 2001), a medicinal plant used in Colombian folk medicine for hypertension. From this plant, we isolated ayanin, a bio¯avonoid that, in-vitro, induces relaxation in Wistar rat aorta mediated by endotheliumdependent NO production and subsequent activation of guanylate cyclase (unpublished data) and that, in-vivo, exerts protective cardiovascular eOE ects against the increase in blood pressure and heart rate also through a mechanism that depends on the NO}cyclic guanosine monophosphate (cGMP) pathway (Guerrero et al 2002). Further phytochemical fractionating of this plant led us to the identi® cation of quercetin 3,7-dimethyl ether (QDME).…”

New cis-Clerodane Diterpenoids from Croton schiedeanus

“…Although in previous studies we have reported the antihypertensive and vaxorelaxant activities of the ethanolic extract from Croton schiedeanus, 15) the diterpenoids 1-6 did not show any significant vasodilator effect in an in vitro screening in rat aortic ring. Extraction and Isolation The dried and triturated aerial part of C. schiedeanus (8 kg) was soaked in 96% EtOH (35 l) at room temperature for three days.…”

Stevia Genus: Phytochemistry and Biological Activities Update

“…subpubescens [ 28 ]. This compound has been reported to have antiasthmatic activity [ 257 ], protective cardiovascular effects [ 258 ], vasorelaxant activity [ 259 ], anti-inflammatory activity [ 260 ], and anticancer properties [ 261 ]. In order to evaluate the use of different natural compounds on the treatment of NTDs, Mahmoud et al [ 262 ] tested ayanin for antiprotozoal activity.…”