The Effect of Dietary Constituents on Toxicity and Carcinogenicity of Aflatoxin B1 in Rats

Abstract

A long-term study, using male Wistar rats, was initiated to determine whether the effects of dietary constituents on AFBl -induced liver cancer could be associated with altered microsomal enzyme activity. They were maintained on mice pellets mixed with specific dietary constituents for 7 days and then given a single carcinogenic dose of AFBl (500ug/rat). After three months, the dietary constituents were discontinued and the animals were left on mice pellets and drinking water only fOr a period of about 20 months. At the end of the trial period" it was observed that dietary mixtures containing small quantities of either B-carotene, ascorbic ,acid, GSH, vitamin E~ s~lenium salt, or uric acid inhibited the development of AFBl - induced liver . cancer and induced increased mdcrosomal enzyme activity at least by 50%.' Where B-carotene and uric acid were the most -e.f f ect Lve inhibitors, vitamin E as was the least, yet a significant inhibitor of liver cancer. Hepatic , levels of cytochrome P-450, aniline hydroxylase and chlorpromazine demethylase were significantly induced (X) in rats fed fortified food followed by AFBl treatment than in control animals. The inhibition of liver cancer by dietary factors was probably due to their ability to induce the activity of hepatic microsomal enzymes. Increased enzyme activity could lead to rapid activation of AFBl metabolites that attack cell components. Inhbition of liver cancer is therefore associated with induction of increased microsomal enzyme activity