Compared Reactivities of Trypanothione and Glutathione in Conjugation Reactions

Abstract

In order to compare the non-enzymatic capacities of the xenobiotic conjugation of trypanothione (a spermidine-glutathione conjugate unique to kinetoplastidae) and glutathione, the reactivity of their respective thiols was investigated. The acido-basic properties of both compounds and their nucleophilicity toward Ellman's reagent and 1-chloro-2,4-dinitrobenzene were studied. Our results show that although glutathione is a better nucleophile than trypanothione, the latter is more reactive because it is more ionized in a large pH range. This pH range likely includes the pH to which such conjugation reactions are expected to happen in vivo. Thus, the better conjugation capacity of trypanothione could make it the cornerstone for the xenobiotic detoxication of trypanosomatidae. © 1994, The Pharmaceutical Society of Japan. All rights reserved.