TY - JOUR
T1 - In vivo effects of difluoromethylornithine on trypanothione and polyamine levels in bloodstream forms of Trypanosoma brucei
AU - Fairlamb, Alan H.
AU - Henderson, Graeme B.
AU - Bacchi, Cyrus J.
AU - Cerami, Anthony
N1 - Funding Information:
The authors would like to thank Ms. Helen Shim for her expert technical assistance, Dr. Peter McCann of the Merrell Dow Research Institute for supplying DFMO and Dr. Anthony Pegg for his gift of dSAM. This research was supported by a grant from the UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (A.H.F.), a grant from the Rockefeller Foundation RF85078#127 (G.B.H.) and NIH grant numbers AI21429 (A.H.F.), AI17340 (C.J.B.) and AI19428 (A.C.).
PY - 1987/6
Y1 - 1987/6
N2 - The effect of d,l-α-difluoromethylornithine (DFMO) on thiol and polyamine levels in Trypanosoma brucei was investigated by isolating trypanosomes from infected rats treated with DFMO for 12-48 h. Concentrations of thiols, polyamines and other amino-compounds were measured by an automated high-performance liquid chromatography method. The levels of DFMO in rat plasma (0.02-1.34 mM) is similar to that found in the parasites (0.27-0.99 mM), concentrations which exceed the Ki of DFMO for T. brucei ornithine decarboxylase. Treatment with DFMO increases intracellular levels of ornithine, S-adenosylmethionine and decarboxylated S-adenosylmethionine and decreases putrescine and spermidine. Putrescine is undetectable after 12 h treatment with DFMO and after 48 h spermidine is decreased by 76%. By 48 h, the spermidine-glutathione conjugates glutathionylspermidine and dihydrotrypanothione (bis(glutathionyl)spermidine) are also decreased by 41 and 66%, respectively. In contrast, levels of glutathione show a slight increase. These changes in metabolite levels are consistent with the biosynthetic pathway proposed for Crithidia fasciculata, where trypanothione is synthesized from spermidine and glutathione via the intermediates N1- and N8-glutathionyl-spermidine. Trypanothione is thought to have two important roles in trypanosomatid metabolism: the maintenance of intracellular thiols in the correct redox state and in the removal of hydrogen peroxide and other hydroperoxides. Thus, it is proposed that depletion of this metabolite may be an important contributory factor to the selective toxic effect of DFMO, particularly in its synergistic effect with other trypanocidal drugs.
AB - The effect of d,l-α-difluoromethylornithine (DFMO) on thiol and polyamine levels in Trypanosoma brucei was investigated by isolating trypanosomes from infected rats treated with DFMO for 12-48 h. Concentrations of thiols, polyamines and other amino-compounds were measured by an automated high-performance liquid chromatography method. The levels of DFMO in rat plasma (0.02-1.34 mM) is similar to that found in the parasites (0.27-0.99 mM), concentrations which exceed the Ki of DFMO for T. brucei ornithine decarboxylase. Treatment with DFMO increases intracellular levels of ornithine, S-adenosylmethionine and decarboxylated S-adenosylmethionine and decreases putrescine and spermidine. Putrescine is undetectable after 12 h treatment with DFMO and after 48 h spermidine is decreased by 76%. By 48 h, the spermidine-glutathione conjugates glutathionylspermidine and dihydrotrypanothione (bis(glutathionyl)spermidine) are also decreased by 41 and 66%, respectively. In contrast, levels of glutathione show a slight increase. These changes in metabolite levels are consistent with the biosynthetic pathway proposed for Crithidia fasciculata, where trypanothione is synthesized from spermidine and glutathione via the intermediates N1- and N8-glutathionyl-spermidine. Trypanothione is thought to have two important roles in trypanosomatid metabolism: the maintenance of intracellular thiols in the correct redox state and in the removal of hydrogen peroxide and other hydroperoxides. Thus, it is proposed that depletion of this metabolite may be an important contributory factor to the selective toxic effect of DFMO, particularly in its synergistic effect with other trypanocidal drugs.
KW - Difluoromethylornithine
KW - Glutathione
KW - High-performance liquid chromatography
KW - Polyamine
KW - Trypanosome
KW - Trypanothione
UR - http://www.scopus.com/inward/record.url?scp=0023253710&partnerID=8YFLogxK
U2 - 10.1016/0166-6851(87)90105-8
DO - 10.1016/0166-6851(87)90105-8
M3 - Article
C2 - 3114634
AN - SCOPUS:0023253710
SN - 0166-6851
VL - 24
SP - 185
EP - 191
JO - Molecular and Biochemical Parasitology
JF - Molecular and Biochemical Parasitology
IS - 2
ER -