Abstract

On a worldwide basis, malaria is a leading cause of morbidity and mortality; the infection is increasing in incidence and prevalence; and drug-resistant parasites have become commonplace. The need for safe new antimalarials is widely acknowledged to be urgent. Antifolate thymidylate synthase inhibitors are a new class of therapeutic agents, and they have potent antimalarial activity in vitro. Selective toxicity is enhanced by coadministration with thymidine. This project will evaluate the activity of antifolate thymidylate synthase inhibitors in mammalian systems. Test compounds will include those already marketed or in clinical trials, as well as novel compounds.
Aim 1 of this project is to evaluate the cytotoxicity of thymidylate synthase inhibitors, with and without concomitant thymidine, against mouse or human cell lines in vitro. Results of these studies, in conjunction with antimalarial potency, will provide a basis for selecting compounds for testing in animals. Treated cells will also be analyzed for intracellular nucleotides, as an indication of the extent of thymidylate synthase blockade and the effectiveness of thymidine protection.
In Aim 2, selected thymidylate synthase inhibitors, alone or in combination with thymidine, will be tested against Plasmodium berghei and P. yoelii in mice. Those with greatest potency and selective toxicity will be candidates for further preclinical testing.
Aim 3 is devoted to studies of thymidine in humans. Thymidine is a nonessential nutrient in the diet, circulates in submicromolar levels in the blood, and has been used parenterally for over 60 years to treat assorted clinical disorders. Remarkably, despite all this there has been no formal study of orally administered thymidine in humans. As a necessary preliminary to the use of combination therapy in patients with malaria, the bioavailability, plasma levels, and nucleotide concentrations in circulating lymphocytes, will be evaluated in healthy volunteers treated with orally administered thymidine.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Program Projects (P01)
Project #
5P01AI060360-05
Application #
7673602
Study Section
Special Emphasis Panel (ZAI1)
Project Start
Project End
Budget Start
2008-07-01
Budget End
2009-04-01
Support Year
5
Fiscal Year
2008
Total Cost
$132,804
Indirect Cost

  Institution

Name
University of Washington
Department
Type
DUNS #
605799469
City
Seattle
State
WA
Country
United States
Zip Code
98195

  Publications

Begley, Darren W; Zheng, Suxin; Varani, Gabriele (2010) Fragment-based discovery of novel thymidylate synthase leads by NMR screening and group epitope mapping. Chem Biol Drug Des 76:218-33
Pang, Cullen K T; Hunter, Joshua H; Gujjar, Ramesh et al. (2009) Catalytic and ligand-binding characteristics of Plasmodium falciparum serine hydroxymethyltransferase. Mol Biochem Parasitol 168:74-83
Gujjar, Ramesh; Marwaha, Alka; El Mazouni, Farah et al. (2009) Identification of a metabolically stable triazolopyrimidine-based dihydroorotate dehydrogenase inhibitor with antimalarial activity in mice. J Med Chem 52:1864-72
Mui, Ernest J; Schiehser, Guy A; Milhous, Wilbur K et al. (2008) Novel triazine JPC-2067-B inhibits Toxoplasma gondii in vitro and in vivo. PLoS Negl Trop Dis 2:e190
Hunter, Joshua H; Gujjar, Ramesh; Pang, Cullen K T et al. (2008) Kinetics and ligand-binding preferences of Mycobacterium tuberculosis thymidylate synthases, ThyA and ThyX. PLoS One 3:e2237
Ganesan, Karthikeyan; Ponmee, Napawan; Jiang, Lei et al. (2008) A genetically hard-wired metabolic transcriptome in Plasmodium falciparum fails to mount protective responses to lethal antifolates. PLoS Pathog 4:e1000214
Gonzales, Joseph M; Patel, Jigar J; Ponmee, Napawan et al. (2008) Regulatory hotspots in the malaria parasite genome dictate transcriptional variation. PLoS Biol 6:e238
Eastman, Richard T; White, John; Hucke, Oliver et al. (2007) Resistance mutations at the lipid substrate binding site of Plasmodium falciparum protein farnesyltransferase. Mol Biochem Parasitol 152:66-71
Mudeppa, Devaraja G; Pang, Cullen K T; Tsuboi, Takafumi et al. (2007) Cell-free production of functional Plasmodium falciparum dihydrofolate reductase-thymidylate synthase. Mol Biochem Parasitol 151:216-9
Hunt, Sonia Y; Detering, Carsten; Varani, Gabriele et al. (2005) Identification of the optimal third generation antifolate against P. falciparum and P. vivax. Mol Biochem Parasitol 144:198-205

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