1. Methylene blue inhibits the asexual development of vivax malaria parasites from a region of increasing chloroquine resistance.
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Suwanarusk, Rossarin, Russell, Bruce, Ong, Alice, Sriprawat, Kanlaya, Chu, Cindy S, PyaePhyo, Aung, Malleret, Benoit, Nosten, François, and Renia, Laurent
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ANTIMALARIALS , *CELL physiology , *CHLOROQUINE , *DRUG resistance , *FLOW cytometry , *MALARIA , *METHYLENE blue , *MICROBIOLOGICAL techniques , *PARASITOLOGY , *PROTOZOA , *RESEARCH funding , *PHARMACODYNAMICS - Abstract
Objectives: Methylene blue, once discarded due to its unsettling yet mild side effects, has now found a renewed place in the pharmacopoeia of modern medicine. The continued spread of drug-resistant Plasmodium vivax and Plasmodium falciparum has also led to a recent re-examination of methylene blue's potent antimalarial properties. Here we examine the ex vivo susceptibility profile of Plasmodium spp. isolates to methylene blue; the isolates were from a region on the Thai-Myanmar border where there are increasing rates of failure when treating vivax malaria with chloroquine.Methods: To do this we used a newly developed ex vivo susceptibility assay utilizing flow cytometry and a portable flow cytometer with a near-UV laser.Results: P. vivax (median methylene blue IC50 3.1 nM, IQR 1.7-4.3 nM) and P. falciparum (median methylene blue IC50 1.8 nM, IQR 1.6-2.3 nM) are susceptible to methylene blue treatment at physiologically relevant levels. Unfortunately, the addition of chloroquine to combination treatments with methylene blue significantly reduces the ex vivo effectiveness of this molecule.Conclusions: Our data support further efforts to employ methylene blue as a safe, low-cost antimalarial to treat drug-resistant malaria. [ABSTRACT FROM AUTHOR]- Published
- 2015
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