Abstract

Chemotherapy of African trypanosomiasis in both the human and animal forms has been confronted with multidimensional problems that include paucity of drugs, resistance, high cost, prolonged treatment protocol and adverse side effects. The main objective of this study was to explore alternative sources of antitrypanosomal agents from the leaves, stem and root barks of Eucalyptus camaldulensis. The plant parts were sequentially extracted with hexane, ethyl acetate, methanol and water; and the extracts screened for antitrypanosomal activity. Mice infected with Trypanosoma brucei brucei were administered intraperitoneally doses ranging from 200-600 mg/kg body weight/day of the extracts for 21 consecutive days. One control group was treated with 3.5mg/kg bodyweight of berenil while the other control group was left untreated. The methanol extract of E. camaldulensis (leaf) produced complete cure for the animals in the different dose groups and survived as long as those treated with the standard drug, berenil, although the clearance time was faster for the standard drug. Sub inoculation of healthy mice with the blood and Cerebrospinal Fluid (CSF) of the cured mice did not result in infection, thus indicating a complete and permanent cure. Acute toxicity studies of the methanol extract of E. camaldulensis (leaf) confirmed the safety of the extract because no mortality was recorded even at 5000 mg/kg bodyweight. However, the extract had no prophylactic activity. Bioassay-guided fractionation of the crude methanol extract of E. camaldulensis leaf gave 10 fractions, with only fractions 8 and 9 exhibiting minimal antitrypanosomal activities that were not comparable to those of the crude extract and the standard drug (p≤0.05). Phytochemical screening revealed the presence of terpenes, steroids, saponins, tannins, alkaloids and fatty acids in both the crude extract and fraction 9; while fraction 8 contained only terpenes, steroids and fatty acids. Data from GC-MS analysis of the two fractions indicated likely components to be methyl esters, amides, long chain alkenes and alcohols. The result of this study shows that the methanol extract of E. camaldulensis (leaf) has immense potential for the development of drugs against African trypanosomiasis.

Keywords:

Antitrypanosomal, cerebrospinal fluid, Eucalyptus camaldulensis, methanol extract, Trypanosomiasis,

References

Competing interests

The authors have no competing interests.

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The authors have no competing interests.