A Dissertation Submitted in Partial Fulfilment of Requirements for Award of a Degree
of Master’s in Life Sciences of Nelson Mandela African Institution of Science and
Technology
Despite past decades of steady advances in reducing severity of Malaria, statistics show that
the disease continues to pose a serious threat to human health. Previous successes in
development of antimalarial drugs from medicinal plants have fuelled research in this area.
However, antimalarial studies to fractionate extracts from such plants have progressed
slowly. This study reports antimalarial potential of fractions from Lippia kituiensis Vatke, for
the first time. Column chromatography was used during fractionation. Antiplasmodial assays
against chloroquine-sensitive (D6) and resistant (W2) Plasmodium strains was done using
hypoxanthine incorporation assay. A colorimetric assay was done to assess cytotoxicity of
fractions against the Vero cell line. Obtained fractions exhibited varied inhibitory
concentrations (IC
50
); with the most efficacious being, Lk-5 (19.45 ± 6.20 μg/ml), Lk-3
(30.43 ± 0.68 μg/ml), Lk-4 (30.82 ± 18.01 μg/ml), and Lk-6 (36.53 ± 14.42 μg/ml) against
D6. Generally, lower activity against W2 was obtained with the most active being Lk-4
(24.18±2.50 μg/ml), and Lk-5 (24.42±5.95 μg/ml), while chloroquine (positive control)
exerted IC
50
of 77.86±4.09 ng/ml (W2) and 15.71±6.49 ng/ml (D6) respectively. Fraction
LK-4 was the most cytotoxic showing cytotoxic concentration of 46.26 μg/ml. When tested
in mice, fractions suppressed Plasmodium berghei significantly compared to the negative
control with Lk-3 being the most efficacious (80.01±1). Due to substantive efficacy, GC-MS
was done on Lk-3 revealing 8 compounds where three have previously been ascribed to
antimalarial activity and other pharmacological effects. This study adds to present knowledge
of antimalarial efficacy of L. kituiensis and provides basis for further work to be done on
isolation of compounds from its extracts.