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University of Nairobi (2011)

Ethnopharmacology, phytochemical composition and toxicity of medicinal plants used against livestock helminths in drylands

Nalule, Sarah A

Titre : Ethnopharmacology, phytochemical composition and toxicity of medicinal plants used against livestock helminths in drylands

Auteur : Nalule, Sarah A

Université de soutenance : University of Nairobi

Grade : Doctor of Philosophy (PhD) 2011

Résumé partiel
Medicinal plants are important natural resources in drylands for communities on which their livestock and other forms of livelihoods have been sustained based on traditional knowledge. However, lack of scientific basis of their biological activity has led to inadequate recognition of the value and acceptance of herbal medicine in livestock healthcare. The main goal of this study was to identify and document ethnopharmacological practices, determine efficacy, phytochemical composition and toxicity of medicinal plants used in treatment of livestock helminths by the agropastoral communities in Nakasongola district of Uganda. A two stage sampling ethno-pharmacological study was carried out with agro-pastoralists in Nakasongola district of Uganda. Participatory methods were used to establish a livestock disease inventory, ethno-diagnosis and medicinal plants used. Qualitative phytochemical screening was conducted on Zathoxylum chalybeum, Euphorbia heterophylla, Rhoicissus tridentata, Secamone africana and Vernonia amygdalina, using standard chemical analysis procedures and thin layer chromatography. In vitro anthelmintic activities on adult worm motility of 70% ethanol and water plants extracts were determined using five serial dilutions with positive and negative controls. Ascaris suum model was used. Acute oral toxicity of E. heterophylla ethanolic extract was conducted using single graded doses ranging from 1500 to 4000mg/kg body weight in mice. Histopathology was carried out using Meyer’s hematoxylin and eosin stain. Generalised Linear Models were performed to determine treatment effects on worms and the extracts’ median effective dose, in addition to determining the median lethal dose of E. heterophylla in mice. The analysis was conducted using graph pad prism version 5.01 computer programme. Trypanosomosis (20.9%), East coast fever (15.5%) and helminthosis (12.8%) were the most prevalent of the 25 diseases prevalent in the study area. Thirty seven plants species belonging to 28 genera and 24 families were reportedly used in treatments against helminthosis. The frequently used plant parts were leaves (54.1 %) and roots (29.7%). Water extraction (81.1 %) was the main method of preparation and oral drenching was the main route of administration. About 65% of the population used combination of traditional and conventional Veterinary medicine. Ethno-diagnosis compared well with veterinary medicine diagnosis. Women were more knowledgeable in disease diagnosis and herbal treatment than the equivalent proportion of men. The five plants studied contained ; tannins, saponins, flavonoids, alkaloids, reducing sugars, coumarins derivatives, anthracenones, anthocyanins with Siafricana lacking saponins and reducing sugars. There was significant difference in the mean yields obtained with ethanol and water plants extracts (p < 0.05) in Z.chalybeum and R.tridentata. Thin layer chromatography characterization with antimony chloride and vanillin sprays indicated presence of polyphenols and sapogenins in all the plants. Chloroform : Methanol (9 : 1, v/v) was found the best solvent for separation of compound in all the plants. The study also revealed plants’ similarities in a number of compounds under different observation conditions. The highest concentration of the aqueous extracts of the z. chalybeum, E.heterophylla, R. tridentata, Siafricana and Viamygdalina at 48 hours, caused percent mean worm motility inhibition of 100%, 100%, 90%, 93.3% and 90% respectively while the ethanol extracts of the same plants inhibited the motility by 93%, 100%, 80.0%, 93.3% and 90% respectively in a dose-dependent response compared with negative control.

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Page publiée le 12 décembre 2014, mise à jour le 23 février 2018