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Drug repositioning as a route to anti-malarial drug discovery: preliminary investigation of the in vitro anti-malarial efficacy of emetine dihydrochloride hydrate.

Matthews H, Usman-Idris M, Khan F, Read M, Nirmalan N - Malar. J. (2013)

Bottom Line: The sum 50% fractional inhibitory concentration (∑FIC₅₀, ₉₀) of the interaction of emetine dihydrochloride hydrate and dihydroartemisinin against the K1 strains of P. falciparum ranged from 0.88-1.48.The results warrant further investigation of emetine dihydrochloride hydrate as a potential stand-alone anti-malarial option.The interaction between the drug and the current front line dihydroartemisinin ranged from additive to mildly antagonistic in the fixed drug ratios tested.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Environment and Life Sciences, University of Salford, M5 4WT, Salford, Manchester, UK. n.j.nirmalan@salford.ac.uk.

ABSTRACT

Background: Drug repurposing or repositioning refers to the usage of existing drugs in diseases other than those it was originally used for. For diseases like malaria, where there is an urgent need for active drug candidates, the strategy offers a route to significantly shorten the traditional drug development pipelines. Preliminary high-throughput screens on patent expired drug libraries have recently been carried out for Plasmodium falciparum. This study reports the systematic and objective further interrogation of selected compounds reported in these studies, to enable their repositioning as novel stand-alone anti-malarials or as combinatorial partners.

Methods: SYBR Green flow cytometry and micro-titre plate assays optimized in the laboratory were used to monitor drug susceptibility of in vitro cultures of P. falciparum K1 parasite strains. Previously described fixed-ratio methods were adopted to investigate drug interactions.

Results: Emetine dihydrochloride hydrate, an anti-protozoal drug previously used for intestinal and tissue amoebiasis was shown to have potent inhibitory properties (IC₅₀ doses of ~ 47 nM) in the multidrug resistant K1 strain of P. falciparum. The sum 50% fractional inhibitory concentration (∑FIC₅₀, ₉₀) of the interaction of emetine dihydrochloride hydrate and dihydroartemisinin against the K1 strains of P. falciparum ranged from 0.88-1.48.

Conclusion: The results warrant further investigation of emetine dihydrochloride hydrate as a potential stand-alone anti-malarial option. The interaction between the drug and the current front line dihydroartemisinin ranged from additive to mildly antagonistic in the fixed drug ratios tested.

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Related in: MedlinePlus

Comparison of parasitized and uninfected blood using the SYBR Green flow cytometric assay. Scatterplots from synchronised (a) uninfected and (b) infected cultures showing the gating strategy that enables the differentiation of mononuclear (ring/trophozoite) and multinuclear (schizont) parasite stages.
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Figure 2: Comparison of parasitized and uninfected blood using the SYBR Green flow cytometric assay. Scatterplots from synchronised (a) uninfected and (b) infected cultures showing the gating strategy that enables the differentiation of mononuclear (ring/trophozoite) and multinuclear (schizont) parasite stages.

Mentions: For the flow cytometric analysis, the gating strategy was adapted as previously described [24] and permitted the differentiation between mononuclear (ring and trophozoite) and multinuclear (schizont) parasite stages in unsynchronized K1 cultures (Figure 2). Accurate determination of percentage parasitaemia was achieved using the BDFACS Verse software programme. The dose response effect of dihydroartemisinin on synchronized K1, P. falciparum cultures initiated at ring stage, was compared between SYBR Green flow cytometric, micro titre plate and traditional Giemsa microscopic assays (Figure 3). IC50 values for cultures sampled at 48 and 72 h post drug exposure were determined and compared using a one-way ANOVA (Graphpad prism). There were no significant differences between the three assays and although the IC50 values appear to be consistently higher at 72 hours than at the 48 hour time point for all three assays (Figure 3) this difference was not found to be significant.


Drug repositioning as a route to anti-malarial drug discovery: preliminary investigation of the in vitro anti-malarial efficacy of emetine dihydrochloride hydrate.

Matthews H, Usman-Idris M, Khan F, Read M, Nirmalan N - Malar. J. (2013)

Comparison of parasitized and uninfected blood using the SYBR Green flow cytometric assay. Scatterplots from synchronised (a) uninfected and (b) infected cultures showing the gating strategy that enables the differentiation of mononuclear (ring/trophozoite) and multinuclear (schizont) parasite stages.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3852733&req=5

Figure 2: Comparison of parasitized and uninfected blood using the SYBR Green flow cytometric assay. Scatterplots from synchronised (a) uninfected and (b) infected cultures showing the gating strategy that enables the differentiation of mononuclear (ring/trophozoite) and multinuclear (schizont) parasite stages.
Mentions: For the flow cytometric analysis, the gating strategy was adapted as previously described [24] and permitted the differentiation between mononuclear (ring and trophozoite) and multinuclear (schizont) parasite stages in unsynchronized K1 cultures (Figure 2). Accurate determination of percentage parasitaemia was achieved using the BDFACS Verse software programme. The dose response effect of dihydroartemisinin on synchronized K1, P. falciparum cultures initiated at ring stage, was compared between SYBR Green flow cytometric, micro titre plate and traditional Giemsa microscopic assays (Figure 3). IC50 values for cultures sampled at 48 and 72 h post drug exposure were determined and compared using a one-way ANOVA (Graphpad prism). There were no significant differences between the three assays and although the IC50 values appear to be consistently higher at 72 hours than at the 48 hour time point for all three assays (Figure 3) this difference was not found to be significant.

Bottom Line: The sum 50% fractional inhibitory concentration (∑FIC₅₀, ₉₀) of the interaction of emetine dihydrochloride hydrate and dihydroartemisinin against the K1 strains of P. falciparum ranged from 0.88-1.48.The results warrant further investigation of emetine dihydrochloride hydrate as a potential stand-alone anti-malarial option.The interaction between the drug and the current front line dihydroartemisinin ranged from additive to mildly antagonistic in the fixed drug ratios tested.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Environment and Life Sciences, University of Salford, M5 4WT, Salford, Manchester, UK. n.j.nirmalan@salford.ac.uk.

ABSTRACT

Background: Drug repurposing or repositioning refers to the usage of existing drugs in diseases other than those it was originally used for. For diseases like malaria, where there is an urgent need for active drug candidates, the strategy offers a route to significantly shorten the traditional drug development pipelines. Preliminary high-throughput screens on patent expired drug libraries have recently been carried out for Plasmodium falciparum. This study reports the systematic and objective further interrogation of selected compounds reported in these studies, to enable their repositioning as novel stand-alone anti-malarials or as combinatorial partners.

Methods: SYBR Green flow cytometry and micro-titre plate assays optimized in the laboratory were used to monitor drug susceptibility of in vitro cultures of P. falciparum K1 parasite strains. Previously described fixed-ratio methods were adopted to investigate drug interactions.

Results: Emetine dihydrochloride hydrate, an anti-protozoal drug previously used for intestinal and tissue amoebiasis was shown to have potent inhibitory properties (IC₅₀ doses of ~ 47 nM) in the multidrug resistant K1 strain of P. falciparum. The sum 50% fractional inhibitory concentration (∑FIC₅₀, ₉₀) of the interaction of emetine dihydrochloride hydrate and dihydroartemisinin against the K1 strains of P. falciparum ranged from 0.88-1.48.

Conclusion: The results warrant further investigation of emetine dihydrochloride hydrate as a potential stand-alone anti-malarial option. The interaction between the drug and the current front line dihydroartemisinin ranged from additive to mildly antagonistic in the fixed drug ratios tested.

Show MeSH
Related in: MedlinePlus