Distribution of Glucosinolates and Myrosinase Activity in Cruciferous Vegetables

A diet rich in curciferous vegetables has been associated with inhibition of chemically induced carcinogenesis in laboratory animals and humans. The underlying mechanism(s) for this inhibition is not completely clear; however, cruciferous vegetables are rich in sulfur-containing glucosides called gluco-sinolates. Myrosinase-mediated breakdown of glucosinolates has been shown to produce compounds with anti-cancer activity. About 100 forms of glucosinolates have been identified, mostly in the Cruciferae family. In this study, we have developed a unique data set of glucosinolate types and amounts in 51 broccoli, three cauliflower, five Brussels sprouts, five cabbage, and two kale lines. The types of glucosinolates and their concentrations were variable among the different genotypes and within each genotype. The dominant glucosinolates in broccoli were glucoraphanin, gluconapin, and glucobrassicin. Glucoraphanin concentration in broccoli ranged from 0.1 μmol·g–1 dry weight in EV6-1 to 21.7 μmol·g–1 dry weight in Brigadier. Concentrations of the other types of glucosinolates in broccoli also showed wide range of variability. In cabbage, Brussels sprouts, cauliflower, and kale, the dominant glucosinolates were sinigrin (7.8, 8.9, 9.3, and 10.3 μmol·g–1 dry weight, respectively) and glucobrassicin (0.9, 3.2, 1.3, and 1.2 μmol·g–1 dry weight, respectively). Brussels sprouts also has significant amounts of gluconapin (6.8 μmol·g–1 dry weight). Myrosinase activity, using sinigrin as substrate, was significantly higher in cabbage, Brussels sprouts, cauliflower, and kale than in broccoli. Wide variations in glucosinolates, glucosinolates content, and myrosinase activity among cruciferous genotypes and within each genotype suggest differences in the health-promoting properties of these vegetables.