Diamidine compounds: Selective uptake and targeting in Plasmodium falciparum

Stead, A.M.W., Bray, P.G., Edwards, I.G., De Koning, H.P. , Elford, B.C., Stocks, P.A. and Ward, S. (2001) Diamidine compounds: Selective uptake and targeting in Plasmodium falciparum. Molecular Pharmacology, 59(5), pp. 1298-1306.

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Publisher's URL: http://molpharm.aspetjournals.org/content/59/5/1298.long

Abstract

Extensive drug resistance in Plasmodium falciparum emphasizes the urgent requirement for novel antimalarial agents. Here we report potent antimalarial activity of a number of diamidine compounds. The lead compound pentamidine is concentrated 500-fold by erythrocytes infected with P. falciparum. Pentamidine accumulation can be blocked by inhibitors of hemoglobin digestion, suggesting that the drug binds to ferriprotoporphyrin IX (FPIX). All of the compounds bound to FPIX in vitro and inhibited the formation of hemozoin. Furthermore, inhibitors of hemoglobin digestion markedly antagonized the antimalarial activity of the diamidines, indicating that binding to FPIX is crucial for the activity of diamidine drugs. Pentamidine was not accumulated into uninfected erythrocytes. Pentamidine transport into infected cells exhibits an initial rapid phase, nonsaturable in the micromolar range and sensitive to inhibition by furosemide and glibenclamide. Changing the counter-ion in the order Cl(-) < Br(-) < NO(2)(-) < I(-) <SCN(-) markedly stimulated pentamidine transport. These data suggest that pentamidine is transported although a pore or ion channel with properties similar to those of the recently characterized 'induced permeability pathway' on the infected red cell membrane. In summary, the diamidines exhibit two levels of selectivity against P. falciparum. The route of entry and molecular target are both specific to malaria-infected cells and are distinct from targets in other protozoa. Drugs that target the hemoglobin degradation pathway of malaria parasites have a proven record of accomplishment. The employment of induced permeability pathways to access this target represents a novel approach to antiparasite chemotherapy and offers an additional level of selectivity.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:De Koning, Professor Harry
Authors: Stead, A.M.W., Bray, P.G., Edwards, I.G., De Koning, H.P., Elford, B.C., Stocks, P.A., and Ward, S.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:Molecular Pharmacology
Journal Abbr.:Mol. Pharmacol.
ISSN:0026-895X
ISSN (Online):1521-0111

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