Oven‐dried Brussels sprouts with undetectable levels of glucosinolates or isothiocyanates increased expression of detoxification enzymes in vitro and in vivo

Abstract

Many individuals use supplementation to increase exposure to crucifers in order to decrease their risk of chronic disease. However supplements require extensive processing including grinding and drying that can affect their ability to induce detoxification enzymes. This study measured the ability of oven‐dried (OD) (without glucosinolates (GLS); without myrosinase activity (MYR)), freeze‐dried (FD) (with GLS; with MYR), and blanched, freeze‐dried (BFD) (with GLS; without MYR) Brussels sprouts to increase detoxification enzyme expression in vitro and in vivo. A 48 hour treatment with OD and FD, but not BFD, Brussels dose‐dependently induced quinone reductase (QR) activity and the expression of RNA for cytochrome P450 (CYP) 1A1, CYP1A2, heme oxygenase, and QR in HepG2 human carcinoma cells. In vivo, mRNA expression of detoxification enzymes was measured in the livers of mice fed diets containing BFD or OD Brussels (20%, 10% or 5%) for 14 days. Mice fed diet containing OD Brussels demonstrated a dose‐dependent induction of CYP1A1, CYP1B1, and QR in the liver, while BFD Brussels had no effect. Despite lacking the phytochemicals typically thought to be responsible, the OD Brussels sprouts induced detoxification enzymes. Additionally BFD Brussels failed to induce detoxification enzymes in vitro and in vivo, suggesting that endogenous myrosinase activity is required for the bioactivity of FD Brussels sprouts.