Effects of malachite green exposure on liver drug metabolizing enzymes and oxidative stress in untreated versus b naphthoflavone pre-treated rainbow trouts (Oncorhyncus mykiss)

Despite the ban imposed by EU, the triphenylmethane dye malachite green (MG) is still illegally used in aquaculture to treat fungal infestations and parasitic diseases. Previous in vitro studies indicate that in the trout MG could inhibit a number of liver drug metabolizing enzymes (DME) and suggest that it may be a CYP1A substrate (1). It is believed that the oxidative metabolism of MG results in the formation of a number of reactive species which may participate in the MG-mediated oxidative stress (OS) (2). This study was designed to characterize the effects of a short MG exposure on DME and OS in the rainbow trout and to study their modulation by the pretreatment with b-naphthoflavone (b-NAF), a model cytochrome P450 (CYP) 1A inducer.