PHYTOCHEMICAL AND PHARMACOLOGICAL STUDIES ON THE LEAF EXTRACT OF STEREOSPERMUM KUNTHIANUM (BIGNONIACEAE)

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Department of Pharmaceutical Sciences

ABSTRACT
Stereospermum kunthianum (Bignoniacea) herb is used in Hausa ethnomedicine in treating bronchitis, veneral diseases, diarrheoa and dysentery. It is also used in the treatment of ulcers, leprosy, skin eruptions, respiratory ailments and gastritis. The plant is common in Northern Nigeria where it is used as abortifacient and as antihypertensive agent. General phytochemical investigation of both petroleum ether and ethanolic extracts of the leaves of Stereospermum, kunthianum revealed the presence of sterol/triterpenes, coumarin, fatty acids while flavones and alkaloids were absent. In the ethanolic extract, sterols/triterpenes saponins, tannins, coumarins and free carboxylic acids were found to be present. Extensive phytochemical, chromatographic and physiochemical and spectroscopic investigation of the petroleum ether extract of the leaves of Stereospermum kunthianum using column chromatography on silica-gel with gradient elution afforded methyl-1-undecyl-2, 3, 3a, 5a, 6, 7, 8, 9, 9a 10, 11, 11a- dodecahydro-IH-cyclopenta[a] phenanthrene -4-carboxy. The structure was established by elemental analysis and the use of ACD/ NMR Assistant (a computer software). Library search and computer interpretation of the 1HNMR spectrum obtained support the molecula formular of the compound as C30 H48O2. Pharmacological studies of the n-butanol extract on isolated rabbit jejunum showed a dose-dependent relaxation of the tissue. The acute toxicity test for the extract in mice established an intraperitioneal LD50 of 3,807.9mg/kg. In castor oil-induced diarrhoea, 60% protection was observed at doses of 500mg/kg and 1000mg/kg respectively. The plant extract exhibited antidiarrheoal activity that was comparable to that of Loperamide 5mg/kg. The result revealed that the extract have pharmacological activity against diarrheoa, this suggests some traditional claims of the plant.