Malaria is recognized as the most widespread parasitic infection in humans. Primaquine has been a major antimalarial drug for over 40 years due to its unique effectiveness against exoerythrocytic forms of the parasite. Its therapeutic value has grown in recent years with the development of resistance to alternate antimalarial drugs such as chloroquine and because of its utility in the treatment of Pneumocystis carinii pneumonia in AIDS patients. However, primaquine therapy has been severely limited because of its capacity to induce methemoglobinemia and hemolytic anemia, particularly in patients with glucose-6-phosphate dehydrogenase deficiency. It has long been known that the hemotoxicity of primaquine is due to the action of metabolites and not the parent compound. However, the toxic specie(s) have not been identified and little is known about the mechanism underlying red cell injury. In collaborative studies with individuals at Walter Reed, we have examined the hemotoxicity of known and putative phenolic metabolites of primaquine and have observed potent and direct-acting hemotoxicity. In other studies, we have synthesized 6-methoxy-8-hydroxylaminoquinoline (MAQ-NOH) and found that this metabolite was also a direct-acting hemotoxicant. We now propose to investigate the mechanism of red cell damage induced by these metabolites and examine their metabolic formation in vitro. The hypotheses under test in this proposal are: 1) that two pathways of oxidative damage, initiated by lipid peroxidation and protein thiol oxidation, occur in the red cell; and 2) that quinone/quinoneimine metabolites act via lipid peroxidation, whereas the N-hydroxy metabolite acts via protein thiol oxidation.
Three aims are presented: 1) to characterize the hemolytic response and pattern of oxidative injury induced within red cells by each type of primaquine metabolite; 2) to elucidate the oxidative metabolism of primaquine in rat and human liver microsomes and hepatocytes, and identify GYP isoforms responsible for primaquine metabolism; and 3) to identify intracellular and external cell surface alterations that correlate with phagocytosis of primaquine metabolite-damaged red cells by cultured splenic macrophages.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI046424-04
Application #
6689578
Study Section
Alcohol and Toxicology Subcommittee 4 (ALTX)
Program Officer
Coyne, Philip Edward
Project Start
2001-01-01
Project End
2005-12-31
Budget Start
2004-01-01
Budget End
2005-12-31
Support Year
4
Fiscal Year
2004
Total Cost
$286,000
Indirect Cost
Name
Medical University of South Carolina
Department
Pharmacology
Type
Schools of Medicine
DUNS #
183710748
City
Charleston
State
SC
Country
United States
Zip Code
29425
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McMillan, David C; Powell, Christine L; Bowman, Zachary S et al. (2005) Lipids versus proteins as major targets of pro-oxidant, direct-acting hemolytic agents. Toxicol Sci 88:274-83
Bowman, Zachary S; Morrow, Jason D; Jollow, David J et al. (2005) Primaquine-induced hemolytic anemia: role of membrane lipid peroxidation and cytoskeletal protein alterations in the hemotoxicity of 5-hydroxyprimaquine. J Pharmacol Exp Ther 314:838-45
McMillan, David C; Sarvate, Snehal D; Oatis Jr, John E et al. (2004) Role of oxidant stress in lawsone-induced hemolytic anemia. Toxicol Sci 82:647-55
Bowman, Zachary S; Oatis Jr, John E; Whelan, Jennifer L et al. (2004) Primaquine-induced hemolytic anemia: susceptibility of normal versus glutathione-depleted rat erythrocytes to 5-hydroxyprimaquine. J Pharmacol Exp Ther 309:79-85
Bolchoz, Laura J C; Gelasco, Andrew K; Jollow, David J et al. (2002) Primaquine-induced hemolytic anemia: formation of free radicals in rat erythrocytes exposed to 6-methoxy-8-hydroxylaminoquinoline. J Pharmacol Exp Ther 303:1121-9
Bolchoz, Laura J C; Morrow, Jason D; Jollow, David J et al. (2002) Primaquine-induced hemolytic anemia: effect of 6-methoxy-8-hydroxylaminoquinoline on rat erythrocyte sulfhydryl status, membrane lipids, cytoskeletal proteins, and morphology. J Pharmacol Exp Ther 303:141-8