Effect of glucosinolate breakdown products on b-naphthoflavone- induced expression of human cytochrome P450 1A1 via the Ah receptor in Hep G2 cells

The ability of glucosinolates, the main bioactive components of brassica vegetables, to influence beta-naphthoflavone-induced transcription of human cytochrome P450 1A1 was examined. Human Hep G2 cells, which contain a functional Ah receptor, were transiently transfected with a reporter construct containing the entire promoter sequence of the human CYP1A1 gene. Breakdown products of four of the glucosinolates tested (prop-2-enyl, 3-methylsulphinylpropyl, 2- hydroxybut-3-enyl and p-hydroxybenzyl), at a concentration as low as 1 microM, reduced the level of beta-naphthoflavone-induced transcription of CYP1A1. It is already known that certain glucosinolate breakdown products can induce phase II enzymes and inhibit the catalytic activity of some cytochrome P450 isoenzymes. This study demonstrates that certain alkyl and aromatic glucosinolates may also influence cytochrome P450 1A1 transcription.