In vivo Antimalarial Activity of the Hydroalcoholic Extract of Rhizomes of Kniphofia foliosa Hochst and Kniphofia insignis Rendle and their Constituents
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Date
2021-03
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Addis Abeba University
Abstract
Malaria is a major public health problem that affects millions of people. The widespread
emergence of antimalarial drug-resistant Plasmodium strains especially the recent emergence of
artemisinin resistance poses a great challenge in future prevention and control of malaria. As a
result, there is an urgent need to discover new, safe, and effective antimalarial drugs with novel
mechanisms of action. In this regard, traditional medicinal plants have paramount importance as
seen in the discovery of the forefront antimalarials. Kniphofia foliosa Hochst and Kniphofia
insignis Rendle are endemic Ethiopian plants traditionally used to treat malaria in different parts
of the country. In the present study the 80% methanol rhizome extracts of both plants and some
of their constituents were investigated for their antimalarial activity.
Fractionation of the hydroalcoholic extract of K. foliosa followed by preparative thin layer
chromatography (PTLC) led to the isolation knipholone, dianellin, 10-knipholone gentibioside
and 12-hydroxypentadec-9-en-1-yl methyl phthalate (HPMP) identified on the basis of
spectroscopic (ESI-MS, 1D and 2D-NMR) data. Similarly, knipholone was isolated for the first
time from crude phenolic fraction of K. insignis. The hydroalcoholic extracts of both plants, the
phenolic fractions from K. foliosa and the compounds isolated thereof showed in
vivo antiplasmodial activity (p<0.001) in Peters‘ 4-day suppressive test against P. berghi infected
Swiss albino mice. Particularly, the hydroalcoholic extract of K. foliosa (400 mg/kg), 10-
knipholone gentibioside (100 mg/kg) and knipholone (200 mg/kg) showed the highest activity
with chemosuppression values of 61.52, 79.00 and 60.16%, respectively. From the dose-response plot, the median effective (ED
50
) doses of 10-knipholone gentibioside, knipholone and dianellin
were determined to be 29.04, 81.25 and 92.31 mg/kg, respectively. Molecular docking study
revealed that knipholone had a strong binding affinity to Plasmodium falciparum l-lactate
dehydrogenase (pfLDH) target. Results of the current study showed that the extracts and
compounds of the plants possess genuine in vivo antimalarial effect against P. berghei in mice,
supporting their traditional use for the treatment of malaria.
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Keywords
Malaria,Plasmodium,Kniphofia foliosa