ABSTRACT

Musanga cecropioides (Umbrella tree) is commonly found and used in tropical parts of Africa and some of its parts are used as hypotensive, antidiabetic, galactogenic, oxytocic and anthelmintic agent.

This work studied the macro- and microscopic structures and various pharmacognostic parameters like the moisture content, extractive values, ash value, acid insoluble and water soluble ash values which can be used in establishing the identity of the stem bark of the plant. It also examined the effect of the water extract of the bark on blood pressure as well as its acute toxicity, and through bioactivity-guided fractionation of the water extract, the work investigated and isolated four compounds two of which were tested for their effects on blood pressure.

The macroscopical examination showed that the bark occurs in quills, it had astringent taste and no characteristic odour. Microscopically, it contained fibres, sclereids, cork cells, prismatic calcium oxalate crystals and vessels. It had a moisture content of 3.68 + 0.06, water and alcohol extractive values of 1.10 + 0.13 and 1.29 + 0.02 respectively, ash value of 10.38 ± 0.12, acid insoluble and water soluble ash values of 1.92 ± 0.01 and 1.89 ± 0.06 % respectively. The water extract exhibited a dose-related hypotensive effect between 10-40 mg/kg and showed negative inotropic and chronotropic effects on the isolated rabbit heart at 0.5 and 1.0mg/ml. It showed no toxic effects in mice at 1-4 g/kg.

Using infra-red, nuclear magnetic resonance and mass spectroscopic methods, two out of the four compounds isolated were found to be 3, 4 – dihydroxybenzoic acid and 3, 4 – dihydroxybenzaldehyde. Although, the two compounds showed similar hypotensive activity at lower doses (2.5-10 mg/kg) than the parent extract, the aldehyde elicited more sustained effects than the acid. Comparisons made with vanillin, vanillic acid and para-hydroxy benzaldehyde showed that the two compounds isolated were not as active as vanillin in reducing blood pressure. However, they were more active than both vanillic acid and para-hydroxy benzaldehyde.