ABSTRACT
An impressive and growing number of bioactive compounds have been identi-ed that have potentially important health benets. These compounds can act as antioxidants, enzyme inhibitors and inducers, inhibitors of receptor activities, and inducers and inhibitors of gene expression, among other actions. Antioxidants are emerging as prophylactic and therapeutic agents. Antioxidants are substances which counteract oxidative stress, which is dened as an imbalance between oxidants and antioxidants in favour of the oxidants, potentially leading to damage (Sies, 1997). The oxidative stress is caused by highly reactive molecules or chemical species containing unpaired electrons known as free radicals. These can greatly reduce the adverse damage due to oxidants by crumbling them before they react with biologic targets, preventing chain reactions or preventing the activation of oxygen to highly reactive products (Azzi et al., 2004). Dietary antioxidants are ‘substances which can (sacricially) scavenge reactive oxygen/nitrogen to stop radical chain reactions, or can inhibit the reactive oxidants from being formed in the rst place’ (Huang et al., 2005, p. 1842). Fruit and vegetable juices are predominately rich sources of polyphenols and carotenoids, and these constituents act as antioxidants. Brassica plants and oilseeds canola, mustard and sunower are potential rich sources of naturally occurring phenolic compounds such as sinapic acid derivatives and chlorogenic acid derivatives. Rapeseed contains more phenolic compounds than most of the other oilseeds (Naczk et al., 1998).
