Xenobiotic metabolism in helminths.
During its life cycle a parasite, like mammals and other organisms, comes into contact with a variety of toxic molecules. In mammals the main line of defence against such compounds is a group of oxidative enzymes that occur predominantly in the liver. Many of these oxidations are dependent on the haemoprotein cytochrome P-450 which serves as a terminal oxidase accepting electrons from NADPH and cytochrome [Formula: see text] . This review by Wendy Precious and John Barrett illustrates that in contrast to mammals, xenobiotic metabolism in both parasitic and free-living platyhelminths and nematodes is predominantly reductive and hydrolytic as the cytochrome P-450 system is absent. This is surprising since it is present in many groups including bacteria, fungi and protozoa, which suggests an ancient origin. The absence of the cytochrome P-450 system not only severely limits the ability of helminths to detoxify compounds but also limits their ability to activate prodrugs.
Department of Biological Sciences, University College of Wales, Aberystwyth, Dyfed, UK.
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Precious
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Barrett