In vitro induction of the anticarcinogenic marker enzyme, quinone reductase, in human hepatoma cells by food extracts.

The effect of vegetable extracts on the activity of the anticarcinogenic phase II marker enzyme, quinone reductase (QR), was investigated by using human Hep G2 cells as the model system. Hep G2 cells were less sensitive than murine Hepa1c1c7 cells to QR-inducible compounds such as tert-butylhydroquinone which have been widely used to examine the QR-inducing activity of the compounds. However, among 45 different vegetable samples, an extract of ashitaba clearly induced QR activity in Hep G2 cells. Ashitaba is therefore considered to have contained certain substances that could induce QR activity, and such induction may play a role in the anticarcinogenic action of vegetables.