ELSEVIER Cancer Letters 99 ( 1996)29-34 CANCER LETTERS IV-Nitrosamines and their effects on the level of glutathione, glutathione reductase and glutathione S-transferase activities in the liver of male mice Salah A. Sheweita*, Mostafa H. Mostafa Depurtment of Environmental Studies, Instttute of Gruduate Studies and Research, Alexundria University, P-0. Box X32, Alexandria, Egypt Received 3 October 1995;accepted24 October 1995 Abstract The present study investigates the influence of different chemical structure of N-nitroso compounds on the hepatic level of reduced glutathione (GSH), glutathione reductase (GSH-R) and glutathione S-transferase (GST) activities in the liver of male Balb/C mice after treatment with 20 mgkg body weight of each compound for 1 h as a single dose. The level of reduced glutathione decreased significantly between 37 and 70% after the treatment of male mice with ethylbutylnitrosamine (-37%). diphenylnitrosamine (-50%), propylbutylnitrosamine (-52%), diethylnitrosamine (-54%), ethylmethylnitrosamine (-55%), and dibutylnitrosamine (-70%), whereas, methylpropylnitrosamine increased the level of GSH by 71%. All the N- nitrosamine compounds tested increased the activity of glutathione reductase except ethylmethylnitrosamine had no effect. The activity of glutathione S-transferase activity was inhibited after treatment of the male mice with diphenylnitrosamine (-60%), dibutylnitrosamine (-6O%), and methylpropylnitrosamine (-81%), while, ethylmethylnitrosamine and ethylbutyl- nitrosamine had no effect on such activity. On the other hand, diethylnitrosamine increased the activity of glutathione S- transferase by 50%. It can be postulated from this study that the chemical structure of N-nitrosamines plays a significant role in the alteration of GSH level and GSH metabolizing enzymes, since the substitution of different groups on the nitroso group was found to be capableof causing an alteration in such activities. Keywords: N-Nitrous compounds;Glutathione; Glutathione S-transferase 1. Introduction N-Nitroso compounds are an important class of environmental carcinogens and their role, as causa- tive agents in the carcinogenesis of some human neoplastic diseases, has been extensively reviewed * Corresponding author. [l-5]. More recent studies have shown that urinary levels of volatile nitrosamines were ten times higher in Schistosome-infected Egyptian patients than either Egyptian or German controls and, further, that levels of non-volatile nitrosamines were two to four times higher than in the control [6-91. Moreover, some N- nitroso compounds have been detected in several dietary items [lo] resulting in an exogenous exposure to these compounds. On the other hand, N-nitros- 0304-3835/96/$12.00 0 1996Elsevier Science Ireland Ltd. All rights reserved SSDI 0304-3835(95)04034-2