Inhibitory effects of kale ingestion on metabolism by cytochrome P450 enzymes in rats.

Kale (Brassica oleracea L. var acephala DC) is a leafy green vegetable belonging to the cabbage family (Brassicaceae) that contains a large amount of health-promoting phytochemicals. There are any reports about the effects of kale ingestion on the chemoprevention function and mechanism, but the interactions between kale and drugs have not been researched. We investigated the effects of kale intake on cytochrome P450 (CYP) metabolism by using cocktail probe drugs, including midazolam (for CYP3A4), caffeine (for CYP1A2), dextromethorphan (for CYP2D6), tolbutamide (for CYP2C9), omeprazole (for CYP2C19), and chlorzoxazone (for CYP2E1). Cocktail drugs were administered into rats treated with kale and cabbage (2000 mg/kg) for a week. The results showed that kale intake induced a significant increase in plasma levels and the AUC of midazolam, caffeine, and dextromethorphan. In addition, the plasma concentration and AUC of omeprazole tended to increase. Additionally, no almost differences in the mRNA expression levels of CYP enzymes in the liver were observed. In conclusion, kale ingestion was considered to have an inhibitory effect on the activities of CYP3A4, 1A2, 2D6, and 2C19 for a reason competitive inhibition than inhibitory changes in the mRNA expressions.