<prompt> Ischemiareperfusion IR injury is considered to be a MAJOR mechanism for organ transplant failure. Allopurinol is used in organ preservation as:AntioxidantPreservativeFree radical scavengerPrecursor for energy metabolism  <response>: The most commonly used solution for organ storage and flushing is the University of Wisconsin solution that contains lactobionate, raffinose, adenosine a precursor for ATP generation, magnesium sulfate to retard calcium influx, glutathione as an antioxidant, and allopurinol to inhibit xanthine oxidase induced reactive oxygen species ROS formation. Ref: Immunobiology of Organ Transplantation edited by David S. Wilkes, William J. Burlingham, 2004, Page 548, 560. 