Hunteria Umbellata (K.Schum.) Hallier F. As A Source of Antiplasmodial Leads: Bioassay-Guided Fractionation of Root Extracts Active Against Multidrug-Resistant Plasmodium Falciparum

Abstract

Background: The emergence and spread of multidrug-resistant Plasmodium falciparum threaten malaria control and underscore the need for new antimalarial leads. Hunteria umbellata (K. Schum.) has a history of traditional medicinal use in Africa, but its antiplasmodial constituents remain insufficiently characterized. This study used bioassay-guided fractionation to enrich antiplasmodial activity in H. umbellata roots against chloroquine-sensitive and multidrug-resistant P. falciparum.

Methods: Root powder was sequentially extracted with solvents of increasing polarity. Extracts were evaluated against 3D7 and Dd2 strains using the SYBR Green I fluorescence assay. The most active extract was fractionated by vacuum liquid chromatography and preparative thin-layer chromatography. Fractions and components were screened to monitor activity enrichment, and resistance indices were calculated.

Results: The dichloromethane extract showed the highest activity, with IC₅₀ values of 7.12 and 8.68 µg/mL against 3D7 and Dd2, respectively. Fraction F5 showed increased activity, with IC₅₀ values of 3.50 and 4.20 µg/mL. Further purification yielded Bioactive Component B, with IC₅₀ values of 2.35 and 2.80 µg/mL, representing approximately three-fold activity enrichment. Resistance indices remained close to unity (1.19–1.22).

Conclusions: Bioassay-guided fractionation successfully enriched antiplasmodial activity in H. umbellata roots, with activity retained against multidrug-resistant P. falciparum. Bioactive Component B warrants further chemical characterization and investigation as a potential source of antimalarial lead compounds.