Antiplasmodial Biflavanones from the Stem Bark of Garcinia buchananii Engl.

Introduction: Plants of the genus Garcinia are traditionally used treat a range of infectious and non-infectious diseases. Garcinia species are reported to have been shown to have a range of biological activities including cytotoxicity antimicrobial, antifungal, antioxidant, antimalarial and HIV-1 protease inhibitory activity among others. Methods: Solvent extraction was done using CH₂Cl₂: MeOH (1:1). Isolation was done using column chromatography with silica gel as the stationery phase and ethyl acetate and n-hexane used as mobile phase in increasing polarity. Thin layer chromatography was used to monitor the isolation. Structure elucidation was done using nuclear magnetic resonance and mass spectroscopic techniques. Chloroquine resistant (W2) and chloroquine sensitive (D6) P. falciparum strains were used for antiplasmodial assay. Results: Further bioassay guided fractionation of a CH₂Cl₂: MeOH (1:1) extract of Garcinia buchananii led to the isolation of two already reported biflavanones, isogarcinol (1) and guttiferone (2) with promising antiplasmodial activity against a chloroquine resistant (W2) Plasmodium falciparum strain with an IC₅₀ of 2.8 ± 0.90 μg/mL for compound 1 and IC₅₀ of 3.94 ± 0.38 μg/mL for compound 2. Compounds 1 and 2 also exhibited moderate activity against the chloroquine sensitive (D6) Plasmodium falciparum strain with IC₅₀ of 7.03±0.60 and 10.64±4.50 μg/mL, respectively. Conclusion: The results provide proof to support the use of G. buchananii by the indigenous community for antimalarial therapy.