FIG. 3.

The conversion of glucoraphanin to sulforaphane, and its subsequent metabolism. Hydrolytic conversion of glucoraphanin to sulforaphane occurs through the action of physical damage to the plant, by either the action of plant-derived myrosinase (intracellular broccoli thioglucosidase) or the microbiota of the human colon. After rapid diffusion into the cells of the intestinal epithelium, sulforaphane undergoes metabolism via the mercapturic acid pathway. This process involves its initial conjugation with glutathione, rapidly catalyzed by important glutathione S-transferase (GST) enzymes. The process of N-acetylation (to form sulforaphane-N-acteylcysteine) is important for the subsequent excretion of sulforaphane from the body.