Ethyl Pyruvate Emerges as a Safe and Fast Acting Agent against Trypanosoma brucei by Targeting Pyruvate Kinase Activity.
BACKGROUND
Human African Trypanosomiasis (HAT) also called sleeping sickness is an infectious disease in humans caused by an extracellular protozoan parasite. The disease, if left untreated, results in 100% mortality. Currently available drugs are full of severe drawbacks and fail to escape the fast development of trypanosoma resistance. Due to similarities in cell metabolism between cancerous tumors and trypanosoma cells, some of the current registered drugs against HAT have also been tested in cancer chemotherapy. Here we demonstrate for the first time that the simple ester, ethyl pyruvate, comprises such properties.


RESULTS
The current study covers the efficacy and corresponding target evaluation of ethyl pyruvate on T. brucei cell lines using a combination of biochemical techniques including cell proliferation assays, enzyme kinetics, phasecontrast microscopic video imaging and ex vivo toxicity tests. We have shown that ethyl pyruvate effectively kills trypanosomes most probably by net ATP depletion through inhibition of pyruvate kinase (Ki = 3.0±0.29 mM). The potential of ethyl pyruvate as a trypanocidal compound is also strengthened by its fast acting property, killing cells within three hours post exposure. This has been demonstrated using video imaging of live cells as well as concentration and time dependency experiments. Most importantly, ethyl pyruvate produces minimal side effects in human red cells and is known to easily cross the blood-brain-barrier. This makes it a promising candidate for effective treatment of the two clinical stages of sleeping sickness. Trypanosome drug-resistance tests indicate irreversible cell death and a low incidence of resistance development under experimental conditions.


CONCLUSIONS
Our results present ethyl pyruvate as a safe and fast acting trypanocidal compound and show that it inhibits the enzyme pyruvate kinase. Competitive inhibition of this enzyme was found to cause ATP depletion and cell death. Due to its ability to easily cross the blood-brain-barrier, ethyl pyruvate could be considered as new candidate agent to treat the hemolymphatic as well as neurological stages of sleeping sickness.
Institute of Biochemistry, Faculty of Medicine, University of Leipzig, Johannisallee 30, 04103, Leipzig, Germany.
Netsanet
N
Worku
Department of Tropical Medicine, Medical Mission Institute, Salvatorstrasse 7, 97067, Würzburg, Germany.
August
A
Stich
Department of Veterinary Parasitology, Faculty of Veterinary Medicine, University of Leipzig, An den Tierkliniken 35, 04103, Leipzig, Germany.
Arwid
A
Daugschies
Department of Physics, Faculty of Natural Sciences, University of Leipzig, Linnéstrasse 5, 04103, Leipzig, Germany.
Iris
I
Wenzel
Institute of Biochemistry, Faculty of Medicine, University of Leipzig, Johannisallee 30, 04103, Leipzig, Germany.
Randy
R
Kurz
Department of Visceral, Transplantation, Thoracic and Vascular Surgery, University Medical Center Leipzig, Liebigstrasse 20, 04103, Leipzig, Germany.
Rene
R
Thieme
Institute of Biochemistry, Faculty of Medicine, University of Leipzig, Johannisallee 30, 04103, Leipzig, Germany.
Susanne
S
Kurz
Institute of Biochemistry, Faculty of Medicine, University of Leipzig, Johannisallee 30, 04103, Leipzig, Germany.
Gerd
G
Birkenmeier
D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003470:Culture Media / Q000737:chemistry; D016503:Drug Delivery Systems / Q000379:methods; D004351:Drug Resistance; D057075:Enzyme Assays; D007700:Kinetics; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011770:Pyruvate Kinase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011773:Pyruvates / Q000494:pharmacology*; D014344:Trypanocidal Agents / Q000494:pharmacology*; D014346:Trypanosoma brucei brucei / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development
D003470:Culture Media; D015800:Protozoan Proteins; D011773:Pyruvates; D014344:Trypanocidal Agents; C046522:ethyl pyruvate; D011770:Pyruvate Kinase