Abstract
Plasmodium falciparum lysate, prepared from 2.7 × 107 ring-infected erythrocytes and incubated with hemoglobin in sodium acetate at pH 5, incorporated a mean of 1.6 nmol of ferriprotoporphyrin IX (FP) into hemozoin in 18 to 22 hr. A similar preparation of trophozoite lysate incorporated a mean of 3.6 nmol of FP into hemozoin in 4 to 6 hr. These findings indicate differences between heme polymerase activity (hemozoin production) at the ring and trophozoite stages of malaria parasites. Intracellular hemozoin production was 90% inhibited at the ring and trophozoite stages by 0.5 and 7 nmol of chloroquine/106 infected erythrocytes. respectively. The inhibition killed the rings but not the trophozoites, suggesting that mature parasites may have a mechanism for protecting themselves against chloroquine-FP toxicity.
Footnotes
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Send reprint requests to: Dr. Augustine U. Orjih, Kuwait University, Faculty of Allied Health Sciences, MLS Department, P.O. Box 31740, Sulaibikhat 90805, Kuwait, Arabian Gulf.
- Abbreviation:
- FP
- ferriprotoporphyrin IX
- Received October 8, 1996.
- Accepted March 6, 1997.
- The American Society for Pharmacology and Experimental Therapeutics
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