Notes: 4-Hydroxyphenylglyoxylic acid is an inhibitor of carnitine palmitoyltransferase 1 (CPT1) and an active metabolite of the prodrug oxfenicine (Item No. 33698).{58439} It inhibits CPT1 in isolated rat liver mitochondria when used at concentrations ranging from 200 to 1,000 µM and inhibits oleate oxidation in isolated rat hepatocytes.{68466}