EFFECTS OF DIETARY ANTICARCINOGENS ON RAT GASTROINTESTINAL GLUTATHIONE-PEROXIDASE ACTIVITY

Several naturally occurring and synthetic food components reduce gastr ointestinal cancer. Many of these compounds are scavengers of free rad icals, formed during oxidative stress. Glutathione peroxidases (GPxs) protect against free radicals by catalysing their inactivation, thereb y consuming glutathione (GSH). This might be one of the mechanisms lea ding to cancer prevention. We studied the effect of several dietary an ticarcinogens on gastrointestinal GPx enzyme activities in male Wistar rats. Total as well as selenium-dependent and non-selenium-dependent GPx (t-GPx, Se-GPx and nSe-GPx) enzyme activities were determined in c ytosolic fractions of oesophagus, gastric and colonic mucosa and liver . d-Limonene induced all three types of GPx activities in the oesophag us. d-Limonene and PEITC induced colonic t-GPX and nSe-GPx activity. B -Carotene induced all three colonic GPx activities and hepatic t-GPx a nd Se-GPx activity. Coumarin and cr-tocopherol induced gastric t-GPx a nd colonic nSe-GPx activity. Oltipraz enhanced oesophageal and gastric t-GPx and oesophageal, gastric and colonic Se-GPx. All other anticarc inogens induced one type of GPx activity at one site. In conclusion, t he specific enhancement of GPx enzyme activities by dietary anticarcin ogens might lead to a more efficient reduction of organic hydroperoxid es and hydrogen peroxide and thus add to prevention of carcinogenesis in these organs.