COMPARISON OF METABOLIC EFFECTS OF VEGETABLES AND TEAS WITH COLORECTAL PROLIFERATION AND WITH TUMOR-DEVELOPMENT IN DMH-TREATED F344 RATS

The aim of this study was to screen potentially chemopreventive vegeta bles and teas for their effects as human dietary components for the co lorectal epithelium and also to seek biomarkers of preventive efficacy . Groups of F344 rats were adapted to a human basal diet supplemented with vegetables or teas, having known contents of glucosinolates, poly phenols and anti-oxidants. Both inductions and suppressions were found for overall glutathione S-transferase (GST) and quinone reductase act ivities. The mitotic index (MI) showed a three-fold range between grou ps; with substantial reductions by black tea, spinach, petit pois and peppers. Changes to PCNA labelling index and proliferation zone were m arginal. No correlation was found between colonic and hepatic enzyme a ctivities, nor with glucosinolate intake. Colonic MI was associated wi th the activity ratio GST(hepatic)/GST(colonic) (r = 0.49, P < 0.002), possibly reflecting a need for direct induction rather than exposure to products of hepatic conjugation. (C) 1997 Elsevier Science Ireland Ltd.