Protective effect of dietary tomatine against dibenzo[a,l]pyrene (DBP)‐induced liver and stomach tumors in rainbow trout

Abstract

The potential anti‐carcinogenic effects of tomatine, a mixture of commercial tomato glycoalkaloids α‐tomatine and dehydrotomatine (10:1), were examined in the rainbow trout chemoprevention model. Prior to the chemoprevention study, a preliminary toxicity study revealed that tomatine in the diet fed daily at doses from 100 to 2000 parts per million (ppm) for 4 weeks was not toxic to trout. For the tumor study, replicate groups of 105 trout were fed diets containing dibenzo[a,l]pyrene (DBP) alone (224 ppm), (N = 3), DBP plus tomatine at 2000 ppm (N = 2), tomatine alone (N = 2), or control diet (N = 2) for 4 weeks. The fish were then returned to control diet for 8 months and necropsied for histopathology. Dietary tomatine was found to reduce DBP‐initiated liver tumor incidence from 37.0 to 19.0% and stomach tumor incidence from 46.4 to 29.4%. Tomatine also reduced stomach tumor multiplicity. The tomatine‐containing diets did not induce mortality, change in fish weights, or liver weights. No adverse pathological effects in the tissues of the fish on the tomatine diets were observed. Dose‐response and chemopreventive mechanisms for tomatine protection remain to be examined. This is the first report on the anticarcinogenic effects of tomatine in vivo.