A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree
of Doctor of Philosophy in Life Sciences and Bioengineering of the Nelson Mandela
African Institution of Science and Technology
This study aimed at evaluating the antimalarial, toxicity and phytochemical profile of Cucumis
metuliferus and Lippia kituiensis used for treatment of malaria in Tanzania. Pulverised plant
materials were sequentially extracted in chloroform, ethyl acetate and methanol, the solvent
was removed using a rotary evaporator. This extracts were evaluated for antimalarial activity
using animal model infected with Plasmodium berghei. The negative and positive controls
were treated with 1% DMSO and chloroquine (CQ) respectively. Cucumis metuliferus
percentage suppression was 98.55%, 88.89% and 84.39% for chloroform, methanolic, and
ethyl acetate extract respectively. For L. kituiensis the percentage suppression was 95.19%,
93.88% and 74.83%, for ethyl acetate, chloroform and methanolic extracts respectively at a
dose of 1500, 600 and 300 mg/kg respectively. Phytochemical profile of C. metuliferus and L.
kituiensis methanolic, ethyl acetate and chloroform leaf extract were also determined by GCMS
technique. The analysis revealed the presence of 11 major compounds. Moreover, the
extracts were evaluated for acute and sub-acute toxicity. In acute toxicity test, the result showed
no significant difference was observed in behavior, body weight and hematology parameters.
The LD
50
of the C. metuliferus and L. kituiensis extracts in mice was determined to be not
greater than 2000 mg/kg body weight. In sub acute toxicity the rats were orally treated with
doses of 150 mg/kg, 300 mg/kg and 500 mg/kg body weight. The results revealed a significant
change in body weight, organ weight, hematological and biochemical parameters of rats
administered with 300 mg/kg and 500 mg/kg body weight. Histopathological examination
revealed the distraction of glomerula and bowman’s capsule, distraction of tubules and
inflammation of kidneys and bile duct hyperplasia, hepatic necrosis and vacuolation of the liver
while the lung showed thickened alveolar wall in a dose of 300 mg/kg and 500 mg/kg body
weight. These findings suggest that C. metuliferus and L. kituiensis have demonstrated
antimalarial activities, but with toxicity. To reduce their toxicity and improve their
pharmacologic properties, the study suggests that isolation, characterization, structural
elucidation of different types of bioactive compound with high potency may serve as candidate
to reduce their toxicity effect and hence developing a new beneficial drug.