Effect of flavonoïds from Arbutus unedo leaves on rat isolated thoracic aorta

Abstract

Arbutus unedo (A. unedo) is a medicinal plant commonly used to treat hypertension and diabetes in Oriental Morocco. Our previous studies showed that A. unedo has a vascular, diuretic, natriuretic, antiagregant and antidiabetic properties. Our goal was to show the vascular action of two groups of flavonoids (free and heterosidic flavonoids) extracted from the leaves of A. unedo on the isolated aorta of rat. A. unedo leaves were collected from Tazekka Mountain (Morocco). Two flavonoïds-enriched (Genins and Heterosids) and a third final aqueous fractions were obtained using the soxhlet refluxing apparatus and tested in vitro on a phenylephrine-precontracted aorta. Thin layer chromatography analysis of both flavonoïds-enriched fractions was performed with silica gel on an aluminum support. The determination of total polyphenolic was achieved using Folin-Ciocalteu method and the total content of flavonoids was determined by aluminum chloride method. The genins-enriched fraction induced a moderate contraction of aorta while the aqueous fraction caused an opposite effect. The heterosids-enriched fraction induced two distinct effects, a relaxation followed by a contraction of the same amplitude. All these effects are endotheliumdependent but not depending on each another. Moreover, the determination of total polyphenolic and flavonoid contents and thin layer chromatography analysis confirmed the abundance of these compounds in the studied fractions of A. unedo leaves. In conclusion, the vasorelaxant property of aqueous and heterosidic fractions are partly attributed to the presence of the flavonoids compounds. These results confirm the validity of the traditional use of A. unedo in hypertension treatment

Keywords

• arbutus unedo, ericaceae, genins
• heterosids, polyphenols, vascular effect.1.