Abstract

ONZAGA, Ingrid L.; RINCON, Javier  and  GUERRERO, Mario F.. Vasorelaxant profile of the extract and an acetylated flavonoid fraction obtained from Calea prunifolia HBK. Colomb. Med. [online]. 2008, vol.39, n.1, pp.33-40. ISSN 1657-9534.

Introduction: This study shows the vasorelaxant profile in isolated aortic rings from Wistar rats of the ethanolic extract and the acetylated flavonoid fraction obtained from Calea prunifolia, specie used in Colombian folk medicine for the treatment of arterial hypertension. Objectives To study possible action mechanisms implicated in the response induced by the ethanolic extract and the acetylated flavonoid fraction obtained from C. prunifolia in isolated aortic rings. Methodology: After verifying the hypotensive effect of the etanolic extract in anaesthetized rats, the response induced by the extract and the acetylated flavonoid fraction (1μg/ml-100 mg/ml) in isolated aortic rings from Wistar rats contracted with KCl (80 mM) or phenylephrine (1μM) was studied. Then, the effect of the extract and the fraction was assessed in deendothelized rings contracted with KCl or in intact rings contracted with KCl (80 mM) and preincubated with one of the following substances: L-NAME (0.1 mM, NO-sintasa inhibitor), methylene blue (1μM, guanyl ciclasa inhibitor), glibenclamide (1μM, K+ATP channel inhibitor), atropine (30μM, muscarinic antagonist), propranolol (1μM, b receptor blocker), or indomethacin (1μM, COX inhibitor). The response induced in rings contracted with CaCl₂ in Krebs solution without Ca₂+ also was analised. Results: The ethanolic extract elicited a dose-response (5-75 mg/kg. iv.) decrease in the blood pressure levels without affecting heart rate in anaesthetized rats. Both, extract and fraction relaxed KCl (80 mM) and phenyle-phrine (1μM) precontracted isolated aorta rings with IC50 of 35 and 67 mg/ml against KCl and 34 and 66 mg/ml against phenylephrine, respectively. Rings exposed to CaCl₂ in Krebs' solution without Ca₂+ showed the better response induced by both extract and fraction. Discussion: These results suggest that acetylated flavonoid compounds play a key role in the vasorelaxant effect induced by C. prunifolia by mechanisms mainly related to calcium channels antagonism.

Keywords : Flavonoids; Nitric oxide; Calcium channels; Vasodilation; Wistar rats; Hypertension.

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