Leishmaniasis is the second-most dreaded parasitic disease in the modern world, behind malaria. The lack of effective vaccines demand improved chemotherapy along with the development of lead compounds and newer targets. We report here that the pentacyclic triterpenoid, dihydrobetulinic acid (DHBA), is a novel lead compound for antileishmanial therapy. It acts by targeting DNA topoisomerases. DNA topoisomerase I and II activity was studied using relaxation and decatenation assays. Mechanistic studies were based on the decreased mobility of enzyme-bound DNA compared with free DNA and the differential mobility of nicked and supercoiled monomers in 1% agarose gel. Pulsed field gradient gel electrophoresis, confocal microscopy, and transmission electron microscopy were performed to assess cytotoxicity of the compound and ultrastructural damage of the parasite. Apoptosis was studied by the isolation of DNA from DHBA-treated parasites and subsequent electrophoresis in 1% agarose gel. DHBA inhibits growth of Leishmania donovani promastigotes and amastigotes with an IC50 of 2.6 and 4.1 µM respectively. The compound is a dual inhibitor of DNA topoisomerases that fails to induce DNA cleavage and acts by preventing the formation of enzyme-DNA binary complex, ultimately inducing apoptosis. Treatment of infected golden hamsters with the compound markedly reduces (> 92%) parasitic burden, both in spleen and liver. Interestingly, the 17-decarboxylated analogue, dihydrolupeol, does not inhibit DNA topoisomerase I and II, has no effect on parasitic growth, and also fails to induce apoptosis. DHBA is a potent antileishmanial agent that induces apoptosis by primarily targeting DNA topoisomerases. Therefore it is a strong candidate for use in designing new antileishmanial drugs.
Dihydrobetulinic Acid Induces Apoptosis in Leishmania donovani by Targeting DNA Topoisomerase I and II: Implications in Antileishmanial Therapy
Arnab Roy Chowdhury,S. Mandal,A. Goswami,M. Ghosh,Labanya Mandal,Debabani Chakraborty,Agneyo Ganguly,G. Tripathi,S. Mukhopadhyay,S. Bandyopadhyay,H. Majumder
Published 2003 in Molecular Medicine
ABSTRACT
PUBLICATION RECORD
- Publication year
2003
- Venue
Molecular Medicine
- Publication date
Unknown publication date
- Fields of study
Biology, Medicine
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
CITATION MAP
EXTRACTION MAP
CLAIMS
CONCEPTS
- apoptosis
A programmed cell-death process assessed in parasite samples using DNA fragmentation and electrophoresis.
- dihydrobetulinic acid
A pentacyclic triterpenoid compound investigated here as a candidate antileishmanial agent.
Aliases: DHBA
- dihydrolupeol
A 17-decarboxylated analogue of dihydrobetulinic acid tested as a structural comparator in the assay set.
- dna topoisomerase i
A DNA-modifying enzyme target examined in the parasite as part of the compound's mechanism-of-action studies.
Aliases: topoisomerase I
- dna topoisomerase ii
A DNA-modifying enzyme target examined in the parasite as part of the compound's mechanism-of-action studies.
Aliases: topoisomerase II
- golden hamster model
An in vivo infection model used to evaluate parasite burden in spleen and liver after treatment.
Aliases: infected golden hamsters, hamster infection model
- leishmania donovani
The Leishmania parasite species used in the promastigote, amastigote, and hamster infection experiments.
Aliases: L. donovani
REFERENCES
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