Glutathione Conjugation of some Xenobiotics by Ascaris suum and Moniezia expansa

Abstract

1. The cestode Moniezia expansa and the nematode Ascaris suum both possess enzymes catalysing the conjugation of glutathione (GSH) with 1-chloro-2, 4-dinitrobenzene.

2. The GSH-S-aryl transferase (GSH-S-transferase A) was present in the cytosol of the cestode proglottids and of the nematode intestinal epithelial cells. Other tissues did not contain measurable activity. The enzymes from both species had mol. wt. of about 37 000 and broad pH optima around pH 8.3. Both enzymes were inhibited by Cu²⁺, Fe³⁺ and Hg²⁺ at 1 mM and stimulated by Co²⁺.

3. Neither M. expansa nor A. suum possessed measurable DDT dehydrochlorinase activity. GSH-S-epoxide transferase (GSH-S-transferase E) activity was indicated in both species; neither species effected the conjugation of bromoor chlorobenzene.

4. Halogenated anthelmintics were not metabolized to GSH conjugates in the helminths studied and did not inhibit GSH-S-aryltransferase activity towards chlorodinitrobenzene.