ABSTRACT

Current efforts to eliminate malaria worldwide are soaring and one of the approaches to this is the mass screening of medicinal plants for their possible potential anti-malarial property. The current study conducted was to determine the effect of one such plant, Cryptolepis sanguinolenta on gametocyte development. In vitro growth inhibition assays on early and late gametocytes stage using ethanolic and aqueous extract of the C. sanguinolenta roots was performed. Enzyme activity assays were conducted to determine the effect of C. sanguinolenta ethanolic extract on aconitase, citrate synthase and α-ketoglutarate dehydrogenase activity in late gametocyte stages. Rhodamine 123 and bodipy-tr ceramide dye labelling of C. sanguinolenta treated gametocytes was also performed to determine the effect of C. sanguinolenta ethanolic root extract on the gametocytes mitochondrial function and the intracellular membranes integrity respectively. C. sanguinolenta inhibited gametocytes with IC50 obtained for C. sanguinolenta ethanolic and aqueous extracts on early gametocyte stages, 307 ± 47.4µg/ml and 305 ± 42.8µg/ml respectively. The IC50 obtained for C. sanguinolenta ethanolic and aqueous extracts on late gametocyte stages were 291.2 ± 24.668µg/ml and 307.3 ± 20.42µg/ml respectively. In the treated late gametocytes stage, C. sanguinolenta ethanolic extract at 90% inhibitory concentration significantly inhibited citrate synthase activity (P = 0.04) and aconitase activity (P = 0.001) but not α-ketoglutarate dehydrogenase activity (P = 0.1). Loss of uptake of Rhodamine 123 dye in the matrix of the ethanolic extract of the C. sanguinolenta treated late gametocytes stage suggested total collapse of the gametocyte’s mitochondrial membrane potential. Consequently, this led to the loss of membrane integrity of other intracellular membranes within the treated late gametocytes stage as observed from the reduced uptake of bodipy-tr ceramide dye. This study suggests that the ethanolic roots extract of the C. sanguinolenta reduced the energy production capability of late gametocyte stages, which consequently impaired their growth and therefore possible loss of their infectivity. 1 C