DIETARY GLUCOSINOLATES AS BLOCKING-AGENTS AGAINST CARCINOGENESIS - GLUCOSINOLATE BREAKDOWN PRODUCTS ASSESSED BY INDUCTION OF QUINONE REDUCTASE-ACTIVITY IN MURINE HEPA1C1C7 CELLS

We have tested the ability of a representative range of dietary glucos inolates and their breakdown products, found in high concentrations in cruciferous vegetables, to act as blocking agents against carcinogene sis by inducing the activity of the anticarcinogenic phase II marker e nzyme quinone reductase in murine hepa1c1c7 cells. Breakdown of glucos inolates was catalysed by the endogenous plant enzyme thioglucoside gl ucohydrolase at neutral and acid pH. Only two unmodified glucosinolate s, p-hydroxybenzyl and 2-hydroxybut-3-enyl, significantly induced quin one reductase activity. However, after enzymic hydrolysis at near-neut ral pH, some of the glucosinolates yielded breakdown products that sig nificantly induced quinone reductase in the order: 3-methylsulphinylpr opyl --> prop-2-enyl --> pent-4-enyl similar to 2-phenylethyl similar to benzyl --> all others tested, Incubation with myrosinase at acidic pH resulted in induction of quinone reductase activity by the hydrolys is products of only three of the tested glucosinolates: 3-methylsulphi nylpropyl similar to 2-phenylethyl --> benzyl --> all others, activity due to the two alkenyl compounds being lost. The results show that th e potential cancer-blocking action of both intact and thioglucoside gl ucohydrolase-treated glucosinolates, as assessed by induction of phase II enzyme activity, is dependent on the nature of the side chain of t he parent glucosinolate.