PT  - JOURNAL ARTICLE
AU  - Abdulsalam A.M. Alkhaldi
AU  - Darren J. Creek
AU  - Hasan Ibrahim
AU  - Dong-Hyun Kim
AU  - Neils B Quashie
AU  - Karl E. Burgess
AU  - Chatchawan Changtam
AU  - Michael P. Barrett
AU  - Apichart Suksamrarn
AU  - Harry P Koning
TI  - Potent Trypanocidal Curcumin Analogs Bearing a Mono-enone Linker Motif Act on Trypanosoma Brucei by Forming an Adduct with Trypanothione
AID  - 10.1124/mol.114.096016
DP  - 2014 Jan 01
TA  - Molecular Pharmacology
PG  - mol.114.096016
4099  - http://molpharm.aspetjournals.org/content/early/2014/12/19/mol.114.096016.short
4100  - http://molpharm.aspetjournals.org/content/early/2014/12/19/mol.114.096016.full
AB  - We have previously reported that curcumin analogs with a C7 linker bearing a C4-C5 olefinic linker with a single keto group at C3 (enone linker) display mid-nanomolar activity against the bloodstream form of Trypanosoma brucei. However, no clear indication of their mechanism of action, or of their superior antiparasitic activity relative to analogs with the original di-ketone curcumin linker, was apparent. In order to further investigate their utility as antiparasitic agents, we here compare the cellular effects of curcumin and the enone linker lead compound, AS-HK014. An AS-HK014-resitant line, TA014, was developed by in vitro exposure to the drug. Metabolomic analysis revealed that exposure to AS-HK014, but not curcumin, rapidly depleted glutathione and trypanothione in the wild-type line, although almost all other metabolites were unchanged relative to control. In TA014 cells thiol levels were similar to untreated wild-type cells, and were not significantly depleted by AS-HK014. Adducts of AS-HK014 with both glutathione and trypanothione were identified in AS-HK014-exposed wild-type cells, and reproduced by chemical reaction. However, adduct accumulation in sensitive cells was much lower than in resistant cells. TA014 cells did not exhibit any changes in sequence or protein levels of glutathione synthetase and γ-glutamylcysteine synthetase relative to wild-type cells. We conclude that mono-enone curcuminoids have a different mode of action than curcumin, rapidly and specifically depleting thiol levels in trypanosomes by forming an adduct. This adduct may ultimately be responsible for the highly potent trypanocidal activity antiparasitic activity of the mono-enone curcuminoids.