Isolation and characterisation of the chemical constituents and the hypoglycaemic potentials of the fruit of Tetrapleura Tetraptera T. (Mimosaceae)

Thumbnail Image
Journal Title
Journal ISSN
Volume Title
The fruit of T. tetraptera is a popular spice and component of many traditional medicinal products in West Africa. It is used for the treatment of various disease conditions including hypertension, malaria, inflammation, leprosy, rheumatoid pains, convulsion and epilepsy. In some communities of Ghana, the fruit is used in the treatment of diabetes mellitus (Amoako-Atta B., Director-CBUD, KNUST, 2001, personal communication). However, there is no scientific data to ascertain this claim. Besides, there is no documentation on the antidiabetic/hypoglycaemic property of the fruit. In the light of these facts, this project was undertaken to investigate the antidiabetic activity of the alcoholic extract of the fruit in normoglycaemic rats and also to isolate and elucidate the structures of the chemical constituents present in the alcoholic extract of the fruit. Basic phytochemical screening of the extract confirmed the presence of saponins, reducing sugars and phenolic compounds. However, cyanogenetic glycosides though previously reported were not detected in this study. Series of column and preparative thin layer chromatography of the alcoholic extract led to the isolation of five compounds. On the basis of spectral data the identities of these compounds were established as sucrose; two known chalcones, 2’, 4, 4’- trihydroxychalcone and 2’, 3, 4, 4’—tetrahydroxychalcone; a known flavanone, 4’, 5, 7- trihydroxyflavanone along with a new monodesmosidic saponin, 3-0- {2’-aceto- ,8-D- glucopyranosyl} olean-12 (13)-ene-28-oic acid. All these isolates except sucrose are being reported in T tetraptera for the first time. The hypoglycaemic effect of the alcoholic extract of the fruit of T. tetraptera was studied in normoglycaemic rats. The extract administered per os at doses of 1000, 2000 and 4000 mg/kg body weight exhibited a biphasic effect in the rats. It caused an initial increase in blood glucose level followed by a falling blood glucose level. The hypoglycaemic effect of the extract at the dose of 2000 mg/kg was comparable to that of glibenclamide (standard drug) between the 2 and 8th hour after administration. In the 10th hour however, the extract at 2000 mg/kg and 4000 mg/kg showed a significantly better (P<0.001) blood glucose lowering effect than the glibenclamide. This thus validates the traditional use of the fruit in the treatment of diabetes mellitus and present an opportunity to develop a molecular antidiabetic drug.
A thesis submitted to the Department of Pharmacognosy, College of Health Sciences, Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirements for the award of Master of Science, 2004