Résumé
Objective: To analyze Myrtus communis chemically and evaluate the hypotensive effects and antioxidant properties of methanol, chloroform, ethyl acetate and aqueous extracts from the leaves of this plant. Methods: Total phenolic and flavonoid contents as well as the antioxidant potential of methanol, chloroform, ethyl acetate and aqueous extracts have been investigated by using different in vitro methods. The hypotensive effects of methanol and ethyl acetate extracts were evaluated in anaesthetized rats by using the method of invasive blood pressure recording. Moreover, ethyl acetate extract was subjected to analysis by different chromatographic methods in order to identify new compounds. Results: Chemical analysis of ethyl acetate extract revealed the presence of myrecitin-3- O-α-rhamnoside. Ethyl acetate extract was found to have the highest total phenolic and total flavonoid contents with the values of 435.37 mg gallic acid equivalents/g dried weight and 130.75 mg quercetin equivalent/g dried weight, respectively. Ethyl acetate extract also exhibited the highest activity in scavenging 2,2-diphenyl-1-picrylhydrazyl, 2,2'-azinobis-(3- ethylbenzthiazoline-6-sulfonic acid), hydroxyl radical and reducing power; whereas, methanol extract exhibited higher chelating activity than ethyl acetate extract did. Chloroform was found to be strong inhibitor of lipid peroxidation in β-carotene bleaching assay (91.19%), ferric thiocyanate method (87.55%), and thiobarbituric acid method (82.59%) as compared to butylated hydroxytoluene. Intravenous administration of methanol and ethyl acetate extract (0.04 to 12 mg/kg body weight) decreased the maximum mean arterial blood pressure with values of 20.6% and 32.49% at 12 mg/kg body weight, respectively in anesthetized rats. Conclusions: This study provides a scientific basis for the use of Myrtus communis in traditional medicine as hypertensive agent as well as additional resources for natural antioxidants.