Bioactivity of Selenium-Enriched Brassica

摘要

@@Brassica vegetables are grown throughout much of the world and are a staple food in many countries.In china,Chinese cabbage and bokchoy are commonly consumed and in Japan and Korea radish and wasabi are more popular.In Europe and the USA cauliflower and broccoli are frequently consumed.In all these countries,cabbage is a common ingredient of the diet. The variation in physical appearance of Brassica vegetables belies the similarities in nutrient and phytochemical content.Most Brassica are a rich source of vitamins A,E and C,as well as folate,calcium and fiber.Furthermore,they all share the ability to synthesize a group of plant secondary compounds,the glucosinolates (GS).Upon crushing or chewing the plant,GS come into contact with the plant enzyme myrosinase,a thiohydrolase that removes glucose from the GS. This allows the remnant to rearrange to a number of alternative products,including bioactive isothiocyanates (ITC).In mammals,ITC activate a host defense system that slows or prevents many chronic diseases.For example,ITC significantly decrease risk for a number of cancers in people who eat 3-5 servings a week.Many genes are upregulated by ITC via the same mechanism,involving an antioxidant response element in the promoter region of each of these genes. This shared mechanism can be used to compare the bioactivity of different ITC.For this reason,the gene nqo1,which encodes the phase Ⅱ detoxification enzyme quinone reductase,comprises an excellent biomarker for health benefits of many ITCs (Munday and Munday,2004).