Effect of oltipraz, alpha-tocopherol, beta-carotene and phenethylisothiocyanate on rat oesophageal, gastric, colonic and hepatic glutathione, glutathione S-transferase and peroxidase.

Four anticarcinogens (oltipraz, alpha-tocopherol, beta-carotene and phenethylisothiocyanate [PEITC]) were studied with respect to their effects on oesophageal, gastric, colonic and hepatic (i) glutathione (GSH) content, (ii) glutathione S-transferase (GST) enzyme activity, (iii) GST isoenzyme levels, and (iv) glutathione peroxidase (GPx) enzyme activity in male Wistar rats. GST enzyme activity was significantly increased in oesophagus (1.9X) and colon (1.2X) by PEITC and in liver (1.4X) by oltipraz. GST Alpha was doubled in the liver by oltipraz, alpha-tocopherol and PEITC. GST Mu levels were increased by beta-carotene and PEITC in stomach and liver, by oltipraz in liver and by alpha-tocopherol in stomach. PEITC induced colonic GST Pi levels (1.3X). GSH content was induced in liver by oltipraz (1.4X) and alpha-tocopherol (1.2X) and in colon by PEITC (1.6X). Each of the anticarcinogens tested increased GPx activity at one or more sites: Se-dependent and total GPx activities were induced in 31.3% and 37.5% of all possibilities, respectively. Major induction in total GPx was found in stomach by alpha-tocopherol (1.8X). In conclusion our data demonstrate that dietary administration of oltipraz, PEITC, alpha-tocopherol and beta-carotene, may exert chemopreventive effects in the digestive tract of the rat by enhancing GST, GPx, and, to a lesser extent, GSH levels.