A comparison of diphenylhydantoin metabolism in different tissues using high performance liquid chromatography

We have quantified diphenylhydantoin metabolism in vitro using high performance liquid chromatography. Five metabolites from rat liver post-mitochondrial supernates were assayed (in order of concentrations): pHPPH, dihydrodiol, pHPPHglucuronide, mHPPH, and an unknown. Catechol was rarely identified and 3-0-methyl catechol was not found. Induction of DPH metabolism by phenobarbital, beta-naphthoflavone, and DPH was studied. While phenobarbital increased synthesis of all the products, beta-naphthoflavone decreased DPH metabolism. DPH itself stimulated only dihydrodiol formation. Studies of dog liver showed that microsomes were more efficient metabolizers of DPH than post-mitochondrial supernatants, with predominance of mHPPH over pHPPH. This finding differed from that with rat liver. Rat thymus lymphocytes and cultured human peripheral blood lymphocytes converted less than 1% of DPH and yielded HPLC profiles indistinguishable from cell-free blanks.