Anticancer enzyme-based dietary manipulating strategies: from the cruciferae extract to the isolated single constituent.

Epidemiological and animal studies linking high and varied fruit and vegetable intake to lower cancer risk, suggest the theoretical possibility that regular, long-term mass administration of isolated naturally occurring dietary constituents can provide a means of controlling cancer incidence. Although no exact mechanism of molecular chemoprotection is known, it is believed that the up-regulation of phase-II metabolizing enzymes by phytoalexins, such as sulforaphane - released from its thioglucoside natural precursor, glucoraphanin, by myrosinase hydrolysis – an isothiocyanate found in Cruciferae, could provide a defence against carcinogens.With the aim to verify such hypothesis, the effects of glucoraphanin supplementation on xenobiotic metabolizing enzymes were thus investigated in male and female Sprague-Dawley rats (aged 6-7 weeks, 150±15 g) receiving per os daily either 24 or 48 mg/kg b.w. glucoraphanin and, for comparison, either 120 or 240 mg/kg b.w. of the palmizio cauliflower extract (PCE – OD74 containing the same amount of glucoraphanin) for four consecutive days; controls received saline only and liver microsomes tested for various CYPs.Glucoraphanin slightly affected phase-II “detoxifying” enzymes, but powerfully induced phase-I bioactivating enzymes (P<0.01, Wilcoxon) such as CYP1A1 (up to ~8.4-fold), CYP3A1/2 (~3-fold), CYP2C11 (~3-fold), CYP1A2 and CYP2B1 (~5.5-fold) and CYP2E1 (~2-fold) associated monooxygenases. Both induction (up to 1.5-fold, for CYP3A1/2) and inactivation (up to 86% loss for CYP2C11) were seen in PCE-OD74 supplemented rats. Results of the most affected isoforms (e.g. CYP3A1/2, CYP1A1/2 and CYP2E1) were sustained by means of Western immunoblotting. CYP induction was paralleled by a corresponding increase in mRNA.Electronic Paramagnetic Resonance (EPR) spectroscopy coupled to a spin-probe technique showed a link between CYP induction and free radical over-generation