Antioxidant Activity of Edible Isothiocyanates

Naturally occurring isothiocyanates (ITCs), products of hydrolysis of glucosinolates (GSLs), attract great attention due to their well-defined indirect antioxidant and antitumor properties, which come as a result of their ability to regulate transcription factors, signaling pathways, cell cycle and apoptosis. Majority of studies on antioxidant activity of ITCs, in particular of those present in Brassica vegetables (sulforaphane, sulforaphene, erucin), indicate that some health-promoting effects might be connected rather with their indirect antioxidant mechanism of action. In this chapter several aspects of chemical and biological activity of ITCs and some parent GSLs are presented, with emphasis on chemical structure, reactivity of isothiocyanate moiety (–NCS) and the role of side chain during reactions with the reactive oxygen species and with model radicals used in common antioxidant assays. The literature survey indicates that at ambient temperatures ITCs are preventive antioxidants removing hydroperoxides and they are not radical trapping agents. However, chain-breaking character can be observed at elevated temperatures during oxidation of bulk phase lipids