Generation of phase II in vitro metabolites using homogenized horse liver

The successful use of homogenized horse liver for the generation of phase I in vitro metabolites has been previously reported by the authors' laboratory. Prior to the use of homogenized liver, the authors' laboratory had been using mainly horse liver microsomes for carrying out equine in vitro metabolism studies. Homogenized horse liver has shown significant advantages over liver microsomes for in vitro metabolism studies as the procedures are much quicker and have higher capability for generating more in vitro metabolites. In this study, the use of homogenized liver has been extended to the generation of phase II in vitro metabolites (glucuronide and/or sulfate conjugates) using 17-estradiol, morphine, and boldenone undecylenate as model substrates. It was observed that phase II metabolites could also be generated even without the addition of cofactors. To the authors' knowledge, this is the first report of the successful use of homogenized horse liver for the generation of phase II metabolites. It also demonstrates the ease with which both phase I and phase II metabolites can now be generated in vitro simply by using homogenized liver without the need for ultracentrifuges or tedious preparation steps. Copyright (c) 2015 John Wiley & Sons, Ltd.