Effects of antimalarial drugs on movement of Plasmodium falciparum

In vitro antimalarial drug susceptibility is conventionally assessed by the concentration dependent growth inhibition of Plasmodium in an in vitro culture system. Inhibition of the kinetic properties of the parasites could provide an alternative method to assess in vitro antimalarial drugs sensitivi...

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Published in:	Southeast Asian journal of tropical medicine and public health Vol. 43; no. 1; pp. 1 - 9
Main Authors:	Wongtanachai, Jaiaue, Silamut, Kamolrat, Day, Nicholas P J, Dondorp, Arjen, Chaisri, Urai
Format:	Journal Article
Language:	English
Published:	Thailand Central Coordinating Board, SEAMEO-TROPMED Project 01-01-2012
Subjects:	Animals Antimalarials - pharmacology Artemisinins - pharmacology Artesunate In Vitro Techniques Inhibitory Concentration 50 Microscopy Movement - drug effects Plasmodium falciparum Plasmodium falciparum - drug effects Quinine - pharmacology Quinolines - pharmacology Trophozoites - drug effects
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Summary:	In vitro antimalarial drug susceptibility is conventionally assessed by the concentration dependent growth inhibition of Plasmodium in an in vitro culture system. Inhibition of the kinetic properties of the parasites could provide an alternative method to assess in vitro antimalarial drugs sensitivity. In this study we used a novel real time microscopic technique, which does not require fixation and staining of the parasite, to study the effects of antimalarial drugs on the intracellular movement of Plasmodium (P.) falciparum trophozoites. Using real time microscopy movement of P. falciparum pigment within erythrocytes was investigated before and after antimalarial drugs exposure (artesunate, quinine, and piperaquine). For artesunate, the 50% inhibition concentration (IC50) at which movement in half of the trophozoites was abolished was estimated by sigmoid curve fitting. Intra- and inter-observer agreements were also assessed. Healthy unexposed P. falciparum trophozoites in culture showed very active movement of malaria pigment. Quinine and piperaquine had no effect but artesunate did reduce pigment movement which started after 2.5 hours exposure to the drug. The mean (SD) IC50 for artesunate regarding abolishment of pigment movement was 54 (14) ng/ml. Assessments of intra- and inter-rater agreement showed good reproducibility of the technique (Kappa value 0.82 to 0.91). Abolishment of active movement of malaria pigment is an alternative approach to assess drug sensitivity for artesunate. Malaria pigment movement is abolished by artesunate early after exposure, but at concentrations higher than those inhibiting growth.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0125-1562