Trypanosoma cruzi dihydrolipoamide dehydrogenase as target of reactive metabolites generated by cytochrome c/hydrogen peroxide (or linoleic acid hydroperoxide)/phenol systems

Abstract

This study determines that cytochrome c (cyt c) catalyses the oxidation of phenol compounds (Phen) in the presence of H₂O₂ or linoleic acid hydroperoxide (LOOH), generating Phen-derived free radicals or other reactive metabolites. These products irreversibly inactivated the dihydrolipoamide dehydrogenase from Trypanosoma cruzi (T cruzi LADH), depending on: the Phen structure, peroxide type, activated cyt c, incubation time and presence of an antioxidant. Nordihydroguaiaretic acid (NDGA) and caffeic acid (CAFF) with cyt c/H₂O₂ or cyt c/LOOH were the most effective inhibitors of T cruzi LADH. The comparison of inactivation values for T cruzi and mammalian heart enzymes demonstrated a greater sensitivity of T cruzi LADH to Phen. GSH, N-acetylcysteine, NAD(P)H, ascorbate and trolox, prevented T cruzi LADH inactivation by acetaminophen. The role of the Phen as potential trypanocidal systems is discussed.

Keywords::

• Dihydrolipoamide dehydrogenase
• Trypanosoma cruzi
• cytochrome c
• peroxides
• phenol compounds

Acknowledgements

JGC dedicates this work to the memory of Professor Dr Andrés O. M. Stoppani. I acknowledge the decisive help of Professor Dr R. Luise Krauth-Siegel (Biochemie-Zentrum, Heidelberg University, Germany) who kindly provided the T. cruzi LADH. I am indebted to Professor Dr Noboru Motohashi (Meiji Pharmaceutical University, Kiyose, Tokyo, Japan) for critical reading of the manuscript.

Declaration of interest: This study was aided by Bioenergetics Research Centre, School of Medicine, University of Buenos Aires. The manuscript was prepared by the author during his stay at the ^¶Instituto de Medicina Tropical ‘Daniel A. Carrión’, Universidad Nacional Mayor de San Marcos. Lima, Perú. JGC is deeply grateful to both Universities for research support and hospitality. The author reports no conflicts of interest. The author alone is responsible for the content and writing of the paper.

This paper was first published online on Early Online on 11 August 2010.