Mono- and Diglucuronide formation from benzo[a]pyrene and chrysene diphenols by AHH-1 cell-expressed UDP-glucuronosyltransferase UGT1A7

Biochem Pharmacol. 1999 Mar 15;57(6):653-6. doi: 10.1016/s0006-2952(98)00337-2.


Polycyclic aromatic hydrocarbon (PAH)-type compounds induce at least two rat UDP-glucuronosyltransferase isoforms, UGT1A6 and UGT1A7. Among the glucuronidation reactions of PAH metabolites studied, mono- and diglucuronide formation of benzo[a]pyrene and chrysene-3,6-diphenol showed the highest induction factors in rat liver microsomes. Availability of AHH-1 cells stably expressing UGT1A7 allowed us to study whether this PAH-inducible isoform could catalyze benzo[a]pyrene and chrysene-3,6-diphenol glucuronidation. It was found that UGT1A7 indeed catalyzed mono- and diglucuronide formation of both benzo[a]pyrene and chrysene 3,6-diphenols. V79 cell-expressed rat UGT1A6 also catalyzed these reactions, except for chrysene diphenol diglucronide formation (Bock et al., Mol Pharmacol 42: 613-618, 1992). Enzyme kinetic studies of the glucuronidation of 6-hydroxychrysene (used as a stable PAH phenol) indicated that UGT1A7 conjugated this compound with a lower apparent Km value (0.1 microM) than UGT1A6 (10 microM). The results suggest that the two PAH-inducible UGTs may cooperate in conjugating PAH metabolites, but that UGT1A7 is more efficient.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzo(a)pyrene / metabolism*
  • Cell Line
  • Chrysenes / metabolism*
  • Glucuronates / analysis
  • Glucuronates / metabolism*
  • Glucuronosyltransferase / biosynthesis
  • Glucuronosyltransferase / metabolism*
  • Hymecromone / metabolism
  • Kinetics
  • Phenols / metabolism
  • Substrate Specificity
  • Transfection


  • Chrysenes
  • Glucuronates
  • Phenols
  • Benzo(a)pyrene
  • 6-hydroxychrysene
  • Hymecromone
  • Glucuronosyltransferase
  • UDP-glucuronosyltransferase, UGT1A7