Pharmacognostic and hypotensive evaluations of the stem bark of Ficus exasperata Vahl (Moraceae)

Abstract

Elevated blood pressure is one of the non-communicable ailments whose control is attempted by the use of medicinal plants in ethnomedicine. In furtherance of our previous work on Ficus exasperata as a plant used in controlling elevated blood pressure, evaluations of the microscopy and other pharmacognostic parameters that could aid in the identification of the plant stem bark were carried out using standard methods. The probable effect of the methanol extract of the stem bark on anaesthetized normotensive rabbit blood pressure was also examined at doses of 5,10,20,30 and 40 mg/kg. The stem bark was observed to occur as flat and channelled pieces when fresh and single quill after drying. The powdered compound contained cork cells, cortical parenchyma, sclereids, fibres and prismatic calcium oxalate crystals as microscopic characters. The percentage weight loss on drying was 6.1 ± 0.15 while the water and alcohol extractive values were1.87 ± 0.04 and 0.59±0.03% respectively. The total ash value was 28.49±0.89 % while the water soluble and the acid insoluble ash values were 2.31± 0.19 and 9.93±0.2% respectively. The preliminary phytochemical results on the stem bark include saponins, tannins, flavonoids and no alkaloids and anthracene derivatives. At 5 mg/kg, the methanol extract of the stem bark produced 6.6±1.2 mmHg fall in mean arterial blood pressure with the effect more pronounced on the systolic  than the diastolic blood pressure. At 10 mg/kg, the reduction in the blood pressure was 15.66±2.9 mmHg after which higher doses did not produce corresponding significant decrease in the blood pressure. Each dose administered was accompanied by corresponding reduction in the heart rate indicating the probable effect of the extract on the myocardium. The results showed that the stem bark of F. exasperata also possess hypotensive effect like the leaf reported earlier.

Keywords: Ficus exasperata, Pharmacognostic parameters; Hypotensive effects

Journal of Pharmacy and Bioresources, Vol. 6 no. 2, pp. 43-49 (September 2009)