Background: Recent epidemiologic studies promote the notion that high intake of food rich in phytochemicals protects against degenerative diseases such as coronary heart diseases and cancer. Phytochemicals are detoxified in mammalian tissues by conjugation with glucuronic acid yielding less active glucuronide conjugates. However, in several tissues glucuronide conjugates are reactivated by the cleaving enzyme beta-glucuronidase. The aim of the present study was to develop a routinely manageable, rapid technique to localize the beta-glucuronidase activity in the small intestinal tissue.
Methods: Histologic slices of rat duodenum, jejunum, and ileum were incubated with a specific chromogenic beta-glucuronidase substrate, 5-bromo-4-chloro-3-indolyl-beta-D-glucuronide (X-GlcU). After enzymatic cleavage, X-GlcU yields 5-bromo-4-chloro-3-indol, a dark blue crystalline precipitate easily monitored by light microscopic technique.
Results: The number and intensity of the crystals were highest in the jejunum and lowest in the ileum. In all three sections of the small intestine, the highest activity was observed at the villar tip and in the tela submucosa and only moderate activity in other layers of the intestinal tissue.
Conclusions: By using the X-GlcU-technique, it could be demonstrated convincingly that beta-glucuronidase exists in all three segments of the rat small intestine. The proposed method is an efficient, simple, and convenient method to visualize beta-glucuronidase activity.