In vivo Antimalarial Activity of the Hydroalcoholic Extract of Kniphofia foliosa Hochst and Its Constituents

Abstract Background: Kniphofia foliosa Hochst is endemic to Ethiopian highlands, where its rhizomes are traditionally used for the treatment of malaria, abdominal cramps and wound healing. As a continuation of our search for antimalarial compounds from Ethiopian medicinal plants, we have tested the 80% methanol extract of K. foliosa rhizomes and its constituents against Plasmodium berghei in mice. Methods: Isolation was carried out using column and preparative thin layer chromatography (PTLC). The chemical structures of the compounds were elucidated by spectroscopic methods (ESI-MS, 1D and 2D-NMR). Peters’ 4-day suppressive test against P. berghei in mice was utilized for in vivo antimalarial evaluation of the test substances. Results: Three compounds, namely knipholone, dianellin, and 12-hydroxypentadec-9-en-1-yl methyl phthalate (HPMP) were isolated and characterized from the 80% methanolic extract of K. foliosa rhizomes. The hydroalcoholic extract (400 mg/kg) and knipholone (200 mg/kg) showed the highest activity with chemosuppression values of 61.52 and 60.16%, respectively. From the dose-response plot, the median effective (ED50) doses of knipholone and dianellin were determined to be 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. Conclusion: Results of the current study support the traditional use of the plant for the treatment of malaria.