Chlorpheniramine, a histamine H1 receptor antagonist, was assayed for in vitro antimalarial activity against multidrug-resistant Plasmodium falciparum K1 strain and chloroquine-resistant P. falciparum T9/94 clone, by measuring the 3H-hypoxanthine incorporation. Chlorphenirame inhibited P. falciparum K1 and T9/94 growth with IC50 values of 136.0+/-40.2 microM and 102.0+/-22.6 microM respectively. A combination of antimalarial drug and chlorpheniramine was tested against resistant P. falciparum in vitro. Isobologram analysis showed that chlorpheniramine exerts marked synergistic action on chloroquine against P. falciparum K1 and T9/94. Chlorpheniramine also potentiated antimalarial action of mefloquine, quinine or pyronaridine against both of the resistant strains of P. falciparum. However, chlorpheniramine antagonism with artesunate was obtained in both P. falciparum K1 and T9/94. The results in this study indicate that antihistaminic drugs may be promising candidates for potentiating antimalarial drug action against drug resistant malarial parasites.
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http://dx.doi.org/10.1016/j.parint.2005.11.058 | DOI Listing |
Antimicrob Agents Chemother
July 2012
National Centre for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Klong Luang, Pathumthani, Thailand.
Natural mutations of Plasmodium falciparum dihydrofolate reductase (PfDHFR) at A16V and S108T specifically confer resistance to cycloguanil (CYC) but not to pyrimethamine (PYR). In order to understand the nature of CYC resistance, the effects of various mutations at A16 on substrate and inhibitor binding were examined. Three series of mutations at A16 with or without the S108T/N mutation were generated.
View Article and Find Full Text PDFAsian Pac J Trop Biomed
January 2012
College of Public Health Sciences, Chulalongkorn University, Bangkok 10330, Thailand.
Objective: To compare the protein patterns from the extracts of the mutant clone T9/94-M1-1(b3) induced by pyrimethamine, and the original parent clone T9/94 following separation of parasite extracts by two-dimensional electrophoresis (2-DE).
Methods: Proteins were solubilized and separated according to their charges and sizes. The separated protein spots were then detected by silver staining and analyzed for protein density by the powerful image analysis software.
Mol Biochem Parasitol
June 2011
Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Malarial parasites exhibit striking genetic plasticity, a hallmark of which is an ever-increasing rate of resistance to new drugs, especially in Southeast Asia where multi-drug resistance (MDR) threatens the last line of antimalarial drugs, the artesunate compounds. Previous studies quantified the accelerated resistance to multiple drugs (ARMD) phenomenon, but the underpinning mechanism(s) remains unknown. We utilize a forward genetic assay to investigate a new hypothesis that defective DNA mismatch repair (MMR) contributes to the development of MDR by Plasmodium falciparum parasites.
View Article and Find Full Text PDFJ Mol Graph Model
November 2009
Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), S.A.S. Nagar 160 062, Punjab, India.
A three-dimensional quantitative structure-activity relationship (3D-QSAR) study was carried out on cycloguanil derivatives which are reported as growth inhibitors of Plasmodium falciparum clone (T9/94 RC17) which harbors A16V+S108T mutant dihydrofolate reductase (DHFR) enzyme. Comparative of Molecular Field Analysis (CoMFA) and Comparative of Molecular Similarity Indices Analysis (CoMSIA) were carried out to investigate the structural requirements for the activities of these compounds and to derive predictive models that may be used for designing novel PfDHFR enzyme inhibitors. The global minimum energy (within the search space) conformation of the most active compound (38) was obtained by using simulated annealing, and was subsequently used as a template to build the structures of the rest molecules used in the study.
View Article and Find Full Text PDFMolecules
July 2009
Department of Chemistry, Faculty of Science, Srinakharinwirot University, Bangkok 10110, Thailand.
This study reports the synthesis of some substituted 5-iodouracils and their bioactivities. Alkylation of 5-iodouracils gave predominately N1-substituted-(R)-5-iodouracil compounds 7a-d (R = n-C(4)H(9), s-C(4)H(9), CH(2)C(6)H(11), CH(2)C(6)H(5)) together with N1,N3-disubstituted (R) analogs 8a-b (R = n-C(4)H(9), CH(2)C(6)H(11)). Their antimicrobial activity was tested against 27 strains of microorganisms using the agar dilution method.
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