Species differences and evolution of xenobiotic metabolizing enzymes

<p>Animals are thought to have adapted to their environment by evolving and developing detoxification enzymes depending on their diet. Herbivorous animals have often had to adapt to the toxic components of plant origin that they constantly ingest, such as plant alkaloids and terpenoids. In mammals, including humans, detoxification of diet-derived chemicals occurs primarily in the liver. Detoxification enzymes that are frequently expressed in the liver include cytochrome P450 in phase I reactions and glucuronyltransferases (UGTs) and sulfotransferases (SULTs) in phase II reactions. These enzymes are thought to have developed specifically in herbivores for detoxification of various toxic chemicals. Carnivorous animals, on the other hand, have relatively little need to deal with detoxification of plant-derived chemicals. In fact, genomic analysis has revealed that more pseudogeneity of xenobiotics-metabolizing enzymes, such as UGT1 and UGT2, occurs in carnivorous animals than in omnivorous animals. Experiments using enzyme fractions of the liver have also revealed that metabolic activity of xenobiotics such as environmental pollutants and pharmaceuticals in the liver is lower than in omnivorous animals. In this symposium, we will report on how mammals with diverse diets have adapted to the xenobiotics ingested daily, especially focusing on the detoxification metabolic capacity of carnivorous animals.</p>