title: Hypericum lanceolatum (Hypericaceae) as a potential source of new anti-malarial agents: a bioassay-guided fractionation of the stem bark.
abstract: BACKGROUND
  Malaria is a major public health threat in Africa, and traditional medicine continues to play a key role in its control especially in rural areas. A bioassay-guided fractionation was carried out in order to evaluate the anti-malarial potential and the safety of the methanol extract of the Hypericum lanceolatum stem bark.
  
  
  METHODS
  The anti-plasmodial activity was assayed by the lactate dehydrogenase method (pLDH) against the multidrug-resistant W2mef laboratory strain, and a field isolate (SHF4) of Plasmodium falciparum. Cytotoxicity tests were carried out using the LLC-MK2 monkey kidney epithelial cells.
  
  
  RESULTS
  Five compounds were isolated from the most active and least cytotoxic ethylacetate sub-extract: betulinic acid (HLT1), 2,2',5,6'-tetrahydroxybenzophenone (HLT2), 5-hydroxy-3-methoxyxanthone (HLT3), 3-hydroxy-5-methoxyxanthone (HLT4) and HLT0 (yet to be identified). Three of the tested compounds presented significant anti-plasmodial activities (with 50% inhibitory concentration, IC₅₀ < 5 μM), with 5-hydroxy-3-methoxyxanthone exerting the highest activity, followed by HLT0 and betulinic acid. All the compounds with significant anti-plasmodial activity were non-cytotoxic, except betulinic acid which showed a 50% cytotoxic concentration, CC₅₀ of 25 μg/mL.
  
  
  CONCLUSIONS
  These findings justify the use of H. lanceolatum stem bark as anti-malarial by traditional healers of Western Cameroon, and could constitute a good basis for further studies towards development of new drug candidates or phytomedicines for malaria.
authors.affiliation: Biotechnology Unit, University of Buea, P.O. Box 63 Buea, South West Region, Cameroon.
authors.forename: Denis
authors.initials: D
authors.lastname: Zofou
authors.forename: Théodora K
authors.initials: TK
authors.lastname: Kowa
authors.forename: Hippolyte K
authors.initials: HK
authors.lastname: Wabo
authors.forename: Moses N
authors.initials: MN
authors.lastname: Ngemenya
authors.forename: Pierre
authors.initials: P
authors.lastname: Tane
authors.forename: Vincent P K
authors.initials: VP
authors.lastname: Titanji
mesh_terms: D000818:Animals; D000962:Antimalarials / Q000302:isolation & purification / Q000494:pharmacology* / Q000633:toxicity; D001681:Biological Assay / Q000379:methods; D002460:Cell Line; D000882:Haplorhini; D020902:Hypericum / Q000737:chemistry*; D024301:Plant Bark / Q000737:chemistry; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology* / Q000633:toxicity; D018547:Plant Stems / Q000737:chemistry; D010946:Plants, Medicinal / Q000737:chemistry; D010963:Plasmodium falciparum / Q000187:drug effects*
chemical_list: D000962:Antimalarials; D010936:Plant Extracts