Fast in vitro methods to determine the speed of action and the stage-specificity of anti-malarials in Plasmodium falciparum

Malaria Journal

Research

Kelly Chibale¹  Yassir Younis¹  Tanya Paquet¹  Leslie Street¹  Claire Le Manach¹  Diego Gonzalez Cabrera¹  Peter Smith²  Xavier C Ding³  David Waterson³  Michael J Witty³  Didier Leroy³  Christian Scheurer⁴  Sibylle Sax⁴  Sarah Schleiferböck⁴  Sergio Wittlin⁴ 

[1] Department of Chemistry, University of Cape Town, 7701, Rondebosch, South Africa;Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, 7925, Observatory, South Africa;Medicines for Malaria Venture, ICC, PO Box 1826, 20 Route de Pré-Bois, 1215, Geneva, Switzerland;Parasite Chemotherapy Unit, Swiss Tropical and Public Health Institute, Basel, Switzerland;University of Basel, CH-4003, Basel, Switzerland;

关键词: Plasmodium falciparum;    Speed of action;    Stage-specificity;   

DOI  :  10.1186/1475-2875-12-424

 received in 2013-09-17, accepted in 2013-11-13,  发布年份 2013

来源: Springer

【 摘 要 】

BackgroundRecent whole cell in vitro screening campaigns identified thousands of compounds that are active against asexual blood stages of Plasmodium falciparum at submicromolar concentrations. These hits have been made available to the public, providing many novel chemical starting points for anti-malarial drug discovery programmes. Knowing which of these hits are fast-acting compounds is of great interest. Firstly, a fast action will ensure rapid relief of symptoms for the patient. Secondly, by rapidly reducing the parasitaemia, this could minimize the occurrence of mutations leading to new drug resistance mechanisms.An in vitro assay that provides information about the speed of action of test compounds has been developed by researchers at GlaxoSmithKline (GSK) in Spain. This assay also provides an in vitro measure for the ratio between parasitaemia at the onset of drug treatment and after one intra-erythrocytic cycle (parasite reduction ratio, PRR). Both parameters are needed to determine in vitro killing rates of anti-malarial compounds. A drawback of the killing rate assay is that it takes a month to obtain first results.MethodsThe approach described in the present study is focused only on the speed of action of anti-malarials. This has the advantage that initial results can be achieved within 4–7 working days, which helps to distinguish between fast and slow-acting compounds relatively quickly. It is expected that this new assay can be used as a filter in the early drug discovery phase, which will reduce the number of compounds progressing to secondary, more time-consuming assays like the killing rate assay.ResultsThe speed of action of a selection of seven anti-malarial compounds was measured with two independent experimental procedures using modifications of the standard [3H]hypoxanthine incorporation assay. Depending on the outcome of both assays, the tested compounds were classified as either fast or non-fast-acting.ConclusionThe results obtained for the anti-malarials chloroquine, artesunate, atovaquone, and pyrimethamine are consistent with previous observations, suggesting the methodology is a valid way to rapidly identify fast-acting anti-malarial compounds. Another advantage of the approach is its ability to discriminate between static or cidal compound effects.

【 授权许可】

Unknown   
© Le Manach et al.; licensee BioMed Central Ltd. 2013. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.