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Trypanocidal CoQ analogues: their effect on other mitochondrial systems
A B Clarkson1, E J Bienen, G Pollakis
1Department of Medical and Molecular Parasitology, New York University School of Medicine, NY 10016.
Summary
Compounds selectively inhibit Trypanosoma brucei brucei respiration, offering potential as anti-parasitic drugs. These agents target the parasite
Area of Science:
- Biochemistry
- Parasitology
- Molecular Biology
Background:
- Protozoan parasites like Trypanosoma brucei brucei rely on specific respiratory pathways.
- Ubiquinone (CoQ) is a critical component in the electron transport chains of both parasites and mammals.
- Developing selective inhibitors is crucial for effective anti-parasitic therapies with minimal host toxicity.
Purpose of the Study:
- To compare the efficacy of various compounds in inhibiting Trypanosoma brucei brucei respiration.
- To assess the selectivity of these inhibitors against parasite mitochondria versus mammalian mitochondria.
- To investigate the mechanism of inhibition and explore similarities/differences in respiratory enzymes.
Main Methods:
- Comparative analysis of salicylhydroxamic acid, substituted benzhydroxamic acids, and dihydroxybenzoic acid esters.
- Testing inhibitor effects on Trypanosoma brucei brucei and rat liver mitochondria.
- Assessing inhibition of ubiquinone function and CoQ-reducing dehydrogenases.
- Evaluating the sensitivity of skunk cabbage alternative oxidase to these inhibitors.
Main Results:
- Compounds demonstrated significant selectivity for inhibiting trypanosome respiration over rat liver mitochondria.
- Minimal inhibition of mammalian mitochondrial function was observed and not due to ubiquinone inhibition.
- Mitochondrial dehydrogenases from various sources were largely insensitive to the inhibitors.
- Skunk cabbage alternative oxidase showed sensitivity to trypanosome respiration inhibitors, suggesting structural similarities but distinct active site environments.
Conclusions:
- The studied compounds exhibit remarkable selectivity, targeting Trypanosoma brucei brucei respiration with low impact on mammalian mitochondria.
- The mechanism of inhibition is not directly related to ubiquinone function in mammalian mitochondria.
- While similarities exist between trypanosome and plant alternative oxidases, their active sites differ, influencing inhibitor response.