PHYTOCHEMICAL, ANALGESIC AND ANTI-INFLAMMATORY STUDIES ON THE METHANOL ROOT EXTRACT OF COMBRETUM HYPOPILINUM (DIELS) OKAFOR (COMBRETACEAE)

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Department of Pharmaceutical Sciences

ABSTRACT
Combretum hypopilinum (Diels) Okafor belongs to the family Combretaceae, and composed of 20 genera with about 500 species. It is a small to medium sized, deciduous shrub or tree growing from 4 - 18 metres in height, with a rounded or flat heavy crown. The plant is used in ethnomedicine for the treatment of pain, snake bites, jaundice, gonorrhoea, gastrointestinal disorder, infertility, tuberculosis and as blood tonic. The aim of the study is to isolate and characterize some of the phytochemical constituent present in the methanol root extract of combretum hypopilinum and to screen the extract for analgesic ant ant-inflammatory activity in mice and rats. The methanol root extract of the plant was subjected to phytochemical screening as well as analgesic and anti-inflammatory studies. The preliminary phytochemical screening of the methanol root extract of Combretum hypopilinum revealed the presence of steroids/triterpenes, flavonoids, tannins, cardiac glycosides, alkaloids, carbohydrates and saponins. The methanol root extract was partitioned successively with chloroform, ethyl acetate and acetone in order of increasing polarity to yield different fractions. Column chromatography separation of ethyl acetate fraction led to the isolation of stigmasterol and Lupeol which are white powdered and white crystalline material with melting points range of 169-1710C and 212-2140C respectively. The structures of these isolated compounds were elucidated using physical test, chemical test, IR and NMR analysis. The intraperitoneal LD50 of the extract was found to be greater than 5000 mg/kg body weight which implies that the extract is relatively safe. The analgesic activity was determined using acetic acid induced writhing, hot plate tests in mice while the anti-inflammatory activity was investigated using carrageenan- induced paw edema test in rats. The extract significantly and dose dependently inhibited the acetic acid-induced writhing in mice. However, the highest protection against writhing was produced by the MRE at a dose of 1000 mg/kg (66.58 %) when compared to the standard drug 69.57 %. The extracts at dose of 500 mg/kg at 90 min showed a significant (P<0.05) increase in the mean reaction time using hot plate method. The carrageenan induced paw oedema was employed in investigating the anti-inflammatory activity in rats. The extract showed significant decreases in paw edema at 4 -5 h of carrageenan injection at all doses tested when compared to the control group at (P<0.05). These results thus, justify the use of the plant in ethnomedicine for the treatment of pain and inflammation. The biological activity might be as a result of the presence of bioactive phytoconstituents present in the methanol root extract.