New antimalarial hits from Dacryodes edulis (Burseraceae)--part I: isolation, in vitro activity, in silico "drug-likeness" and pharmacokinetic profiles

PLoS One. 2013 Nov 8;8(11):e79544. doi: 10.1371/journal.pone.0079544. eCollection 2013.

Abstract

The aims of the present study were to identify the compounds responsible for the anti-malarial activity of Dacryoedes edulis (Burseraceae) and to investigate their suitability as leads for the treatment of drug resistant malaria. Five compounds were isolated from ethyl acetate and hexane extracts of D. edulis stem bark and tested against 3D7 (chloroquine-susceptible) and Dd2 (multidrug-resistant) strains of Plasmodium falciparum, using the parasite lactate dehydrogenase method. Cytotoxicity studies were carried out on LLC-MK2 monkey kidney epithelial cell-line. In silico analysis was conducted by calculating molecular descriptors using the MOE software running on a Linux workstation. The "drug-likeness" of the isolated compounds was assessed using Lipinski criteria, from computed molecular properties of the geometry optimized structures. Computed descriptors often used to predict absorption, distribution, metabolism, elimination and toxicity (ADMET) were used to assess the pharmacokinetic profiles of the isolated compounds. Antiplasmodial activity was demonstrated for the first time in five major natural products previously identified in D. edulis, but not tested against malaria parasites. The most active compound identified was termed DES4. It had IC50 values of 0.37 and 0.55 µg/mL, against 3D7 and Dd2 respectively. In addition, this compound was shown to act in synergy with quinine, satisfied all criteria of "Drug-likeness" and showed considerable probability of providing an antimalarial lead. The remaining four compounds also showed antiplasmodial activity, but were less effective than DES4. None of the tested compounds was cytotoxicity against LLC-MK2 cells, suggesting their selective activities on malaria parasites. Based on the high in vitro activity, low toxicity and predicted "Drug-likeness" DES4 merits further investigation as a possible drug lead for the treatment of malaria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antimalarials / chemistry
  • Antimalarials / isolation & purification
  • Antimalarials / pharmacology*
  • Antimalarials / toxicity
  • Artemether
  • Artemisinins / chemistry
  • Burseraceae / chemistry*
  • Cell Line
  • Drug Interactions
  • Drug Resistance, Multiple
  • Epithelial Cells / drug effects
  • Haplorhini
  • Models, Molecular
  • Plant Extracts / chemistry
  • Plant Extracts / isolation & purification
  • Plant Extracts / pharmacology*
  • Plant Extracts / toxicity
  • Plasmodium falciparum / drug effects
  • Quinine / chemistry
  • Toxicity Tests

Substances

  • Antimalarials
  • Artemisinins
  • Plant Extracts
  • Quinine
  • Artemether

Grants and funding

This work was financially supported by a research grant awarded to Dr. Denis Zofou by the International Foundation for Science, Stockholm, Sweden / Organisation for the Prohibition of Chemical Weapons, The Hague, The Netherlands (IFS/OPCW) grant (number F/5122-1) (www.ifs.se). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.