Phenolic compounds have been studied for their ability to chelate redox-active metal ions, to inhibit LDL cholesterol oxidation, and to neutralize other processes involving ROS, since they are efficient free radical scavengers . Moreover, dietary polyphenols may inhibit the growth of adipose tissue by modulating adipocyte metabolism . It is reported that polyphenols are able to enhance glucose uptake in adipocytes and muscle cells by GLUT4, a glucose transporter that exerts its action through the AMP-activated protein kinase pathway . It has also been demonstrated that flavonoids can normalize blood glucose levels and promote β-cell regeneration in islets of alloxan-treated rats , while epicatechin and quercetin can improve insulin production in isolated rat islets . Turnip leaf (Brassica rapa) extracts, which are rich in flavonoids and tannins, showed an anti-hyperglycemic activity in alloxan-induced diabetic rats . In general, different varieties of broccoli may have different total phenolics content, ranging from 5 up to 8 mg/g dry weight (DW) . The amount of total phenolics in Brassica may be further increased by using specific agronomic techniques, such as sulphur fertilization and/or light-treatment .