Bioassay-Guided Fractionation of Hunteria Umbellata (K.Schum.) Hallier F. Root Reveals Selective Antiplasmodial Activity Against Chloroquine-Sensitive and Multidrug-Resistant Plasmodium Falciparum

Abstract

Ethnopharmacological Relevance: Hunteria umbellata (K.Schum.) Hallier f. is used in West African traditional medicine for several ailments, including febrile conditions. However, evidence for antiplasmodial activity of its root and enrichment of active constituents by bioassay-guided fractionation is limited.

Aim of the Study: To investigate the antiplasmodial activity of H. umbellata root against chloroquine-sensitive 3D7 and multidrug-resistant Dd2 Plasmodium falciparum and assess activity enrichment by bioassay-guided fractionation.

Materials and Methods: Root material was sequentially extracted with solvents of increasing polarity. Extracts were screened for phytochemical constituents, and the most active extract was fractionated by vacuum liquid chromatography and further purification. Antiplasmodial activity against 3D7 and Dd2 was assessed using a SYBR Green I assay. Cytotoxicity was evaluated in Vero cells using the MTT assay. Selectivity and resistance indices were calculated.

Results: The dichloromethane extract showed the highest activity, with IC50 values of 7.12 ± 0.02 and 8.68 ± 0.02 µg/mL against 3D7 and Dd2, respectively. Fraction F5 showed increased activity (IC50 3.50 ± 0.20 and 4.20 ± 0.20 µg/mL), while bioactive component B showed the highest activity (2.35 ± 0.02 and 2.80 ± 0.02 µg/mL). Bioactive Component B had a Vero-cell CC50 of 132.80 ± 1.85 µg/mL, with selectivity indices of 56.51 and 47.43. Resistance indices ranged from 1.19 to 1.22.

Conclusion: Bioassay-guided fractionation enriched antiplasmodial activity in H. umbellata root. Bioactive component B retained activity against Dd2 and showed favourable in vitro selectivity, supporting further chemical characterization and mechanistic investigation. The findings are consistent with the documented traditional use of the species for febrile conditions but do not establish traditional antimalarial efficacy.