Blood Pressure-lowering activity of Extract and Fractions of Persea americana Leaf

Abstract

Persea americana leaf is used in ethnomedicine to treat hypertension, but with limited scientific justification. This study evaluated the antihypertensive properties of fractions of P. americana leaf in rats.  Persea americana leaf was extracted in 95% methanol and partitioned into five fractions. Thirty-five noradrenaline-induced hypertensive Wistar rats distributed into seven groups (n=5) were treated intravenously with normal saline; 0.6 mL/kg (control), ME (100 mg/kg), fractions (100 mg/kg); n-hexane, dichloromethane, chloroform, ethyl acetate or n-butanol. The ethyl acetate fraction (EF) which was the most active fraction was fractionated on silica gel using column chromatography. Four fractions (EFCF1, EFCF2, EFCF3 and EFCF4) were obtained and evaluated at 25 mg/kg for antihypertensive activity in noradrenaline-induced hypertension using twenty rats. The systolic, diastolic blood pressure, heart rate and mean arterial pressure (MAP) were used as indices for antihypertensive activity. The constituents of EFCF3 were identified by GC-MS. Data were analysed using descriptive statistics and ANOVA at α 0.05. The ME, EF and EFCF3 produced the most pronounced reduction in systolic and diastolic blood pressure in noradrenaline-induced raised blood pressure. Percentage reductions in noradrenaline-induced raised MAP were 31.6, 32.0 and 32.3% for ME (100 mg/kg), EF (100 mg/kg), and EFCF3 (25 mg/kg) respectively. EFCF3 produced better reduction in MAP than standard drugs (labetalol and phentolamine).  In addition, only ME produced significant reduction on heart rate. The major constituents of the most active column fraction of P. americana leaf (EFCF3) are 11-Tetradecyn-1-ol acetate, 14-methyl-(Z)-8-Hexadecenal and Cyclopropane carboxaldehyde.  Persea americana demonstrates in vitro and in vivo antihypertensive activities.