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- Title
Cyclization-blocked proguanil as a strategy to improve the antimalarial activity of atovaquone.
- Authors
Skinner-Adams, Tina S.; Fisher, Gillian M.; Riches, Andrew G.; Hutt, Oliver E.; Jarvis, Karen E.; Wilson, Tony; von Itzstein, Mark; Chopra, Pradeep; Antonova-Koch, Yevgeniya; Meister, Stephan; Winzeler, Elizabeth A.; Clarke, Mary; Fidock, David A.; Burrows, Jeremy N.; Ryan, John H.; Andrews, Katherine T.
- Abstract
Atovaquone-proguanil (Malarone®) is used for malaria prophylaxis and treatment. While the cytochrome bc1-inhibitor atovaquone has potent activity, proguanil's action is attributed to its cyclization-metabolite, cycloguanil. Evidence suggests that proguanil has limited intrinsic activity, associated with mitochondrial-function. Here we demonstrate that proguanil, and cyclization-blocked analogue tBuPG, have potent, but slow-acting, in vitro anti-plasmodial activity. Activity is folate-metabolism and isoprenoid biosynthesis-independent. In yeast dihydroorotate dehydrogenase-expressing parasites, proguanil and tBuPG slow-action remains, while bc1-inhibitor activity switches from comparatively fast to slow-acting. Like proguanil, tBuPG has activity against P. berghei liver-stage parasites. Both analogues act synergistically with bc1-inhibitors against blood-stages in vitro, however cycloguanil antagonizes activity. Together, these data suggest that proguanil is a potent slow-acting anti-plasmodial agent, that bc1 is essential to parasite survival independent of dihydroorotate dehydrogenase-activity, that Malarone® is a triple-drug combination that includes antagonistic partners and that a cyclization-blocked proguanil may be a superior combination partner for bc1-inhibitors in vivo. Tina Skinner-Adams et al. show that proguanil and the cyclization-blocked analogue, tBuPG, have potent, anti-plasmodial activity in vitro. This study suggests that a cyclization-blocked proguanil may be a superior combination partner for bc1-inhibitors to suppress the survival of malarial parasites.
- Subjects
RING formation (Chemistry); ANTIMALARIALS; ATOVAQUONE; PREVENTIVE medicine; CYTOCHROME P-450; FOLIC acid metabolism
- Publication
Communications Biology, 2019, Vol 2, Issue 1, pN.PAG
- ISSN
2399-3642
- Publication type
Article
- DOI
10.1038/s42003-019-0397-3