RESUMO
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.
RESUMO
Dracaena cinnabari, known as the dragon's blood tree, has been used for long time in the Yamani and Arabian folk medicine for many claimed ailments. Chemical analysis of the resin of D. cinnabari resulted in the isolation of the five flavonoiud from the chloroform extract: 4,4'-dihydroxy-2'-methoxychalone, 4,4'-dihydroxy-2-methoxydihydrochalone, 7-hydroxy-3-[3-hydroxy-4-methoxybenzyl] chroman, 7-hydroxy-3-[4-hydroxybenzyl] chroman, and 2',4,4'-trithydroxychalcone; with the latter flavonoid being isolated for the first time from this species. The aqueous extract [AE] of the resin of D. cinnabari, in concentrations ranging from 10[-4] to 0.03 mg/ml, caused concentration-dependent decrease of amplitude of the phasic contractions and relaxed the tone of the longitudinal segments of ileum and uterus, and urinary bladder rings. Bolus injection of AE [10[04] - 0.03 mg] increased the contractility but had no significant effect on the beating rate of the isolated perfused heart of the rat; it also had a hypotensive effect in anesthetized rats when injected in i.v. doses from 0.04 - 12 mg/kg body weight. AE [800 and 1600 mg/kg] increased significantly that rate of urine excertion in conscious rats when administered orally. These observations indicate that resin AE of D. cinnabari has spansmolytic, inotropic, hypotensive and diuretic effects on rats. Furthermore, the observations were discussed in relation to the claimed uses of D. cinnabari resin in folk medicine