Glutathione S-transferases (GSTs), found in virtually all eukaryotes, are a multigene family of phase-II metabolic enzymes, which catalyze the conjugation of reduced glutathione with a variety of endogenous and exogenous electrophilic compounds, including several potentially toxic carcinogens and chemotherapeutic drugs (Hayes et al., 2005), thereby reducing the reactivity of the compounds by making them water soluble and favouring their elimination from the body.