Glutathione S-transferase subunit induction patterns of Brussels sprouts, allyl isothiocyanate and goitrin in rat liver and small intestinal mucosa: A new approach for the identification of inducing xenobiotics

Effects of Brussels sprouts (2.5–30%), allyl isothiocyanate (0.03 and 0.1%) and goitrin (0.02%), in the diet, on the glutathione S-transferase subunit pattern in the liver and small intestinal mucosa of male Fisher rats were investigated. A statistically significant linear relationship was found between the amount of Brussels sprouts in the diet and the induction of glutathione S-transferase subunits in two experiments. Increases in total activity of glutathione S-transferases towards 1-chloro-2,4-dinitrobenzene ranged from about 15% (2.5% Brussels sprouts in the diet) to 180% (30% Brussels sprouts in the diet) in the liver, and from 3% (2.5% Brussels sprouts) to 150% (30% Brussels sprouts) in the small intestinal mucosa. There were similar increases in the total amounts of glutathione S-transferase subunits. In the first experiment, when the average sinigrin and progoitrin levels found in the sprouts were 1835 and 415 μmol/kg, respectively, subunit induction patterns in both the liver and the small intestinal mucosa were very similar to the pattern observed after feeding allyl isothiocyanate. In the second experiment, when the average sinigrin level found in the sprouts was as low as the progoitrin level (both about 540 μmol/kg), a goitrin-like induction pattern was observed. The most pronounced difference between the glutathione S-transferase subunit induction patterns due to administration of allyl isothiocyanate and goitrin is the much stronger enhancement of subunit 2 by allyl isothiocyanate. The induction patterns of both experiments indicate that in Brussels sprouts at least two compounds, probably allyl isothiocyanate and goitrin, are responsible for the induction of glutathione S-transferases.