Hypoglycaemic potential of some Kenyan plants used in traditional medicine in Laikipia and Mbeere districts and Nairobi Province
Kibiti, Mwiti Cromwell
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Diabetes mellitus is a chronic physiological metabolic disorder caused by inherited and/or acquired deficiency in production of insulin by pancrease or by the ineffectiveness of the insulin produced. The prevalence of diabetes in adults globally was estimated to be 4.0`x, in 1995 and was projected to rise to 5.4% (300 million) by the year 2025. In Kenya, it was estimated to be 1.06% in 2000 and projected to rise to 1.32% by the year 2025. Conventional drug therapy though effective in the management of diabetes mellitus is expensive and has toxic side effects. Herbal medicine would thus provide alternative therapy if effective and less toxic. Ho«-ever, their safety and effectiveness has not been investigated. The aim of this study is therefore to assess whether aqueous leaf extracts of Aloe secundiflora, Olea africana, Pentas zanzibarica and Rumex abyssinicus; root extracts of Terminalia brownii; root tuber extracts of Rhoicissus trideniaia and stem bark extracts of Warburgia salutaris had in vivo hypoglycaemic activity in alloxan induced diabetic mice. The seven plants were collected from Rift Valley and Eastern provinces using ethno-botanical and pharmacological information obtained from traditional healers. Elemental analysis of the extracts was done using energy dispersive X-ray fluorescence spectrometry and atomic absorption spectrometry. Phytochemical screening of the extracts was done to determine the class of secondary metabolites present in the plant extracts. Histological assessment was done to evaluate the toxicological effects of the extracts on the various organs. Out of the seven plants, six aqueous leaf extracts of Aloe secundiflora, Olea africana and Pentas zanzibarica; root extracts of Terminalia browni; root tuber extracts of Rhoicissus tridentata and stem bark extracts of Warburgia salutaris showed blood glucose lowering effect in alloxan induced diabetic mice. The elements Cr, Cu, Fe, Pb, Ni, Mg, Mn, Mo, Sr and Zn were present in the plant extracts but in different quantities. Alkaloids, saponins, tannins, terpenoids, sterols, flavanoids and anthraquinones were present in some of the plants. On histological assessment, aqueous leaf extracts of Olea africana had no effects on the livers, spleens, hearts, lungs and kidneys. Among the plants with hypoglycaemic activity, Olea africana is safe to serve as an alternative therapy for diabetes management. However, though the other plant extracts showed toxicity, they continue to be used to manage diabetes mellitus since the observed toxicity of single plant extracts is reduced by combining extracts from different plants.
- MST-Zoological Sciences