A novel activity of microsomal epoxide hydrolase: Metabolism of the endocannabinoid 2-arachidonoylglycerol

Kasem Nithipatikom, Michael P. Endsley, Adam W. Pfeiffer, J R Falck, William B. Campbell

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Microsomal epoxide hydrolase (EPHX1, EC is a highly abundant α/β-hydrolase enzyme that is known for its catalytical epoxide hydrolase activity. A wide range of EPHX1 functions have been demonstrated including xenobiotic metabolism; however, characterization of its endogenous substrates is limited. In this study, we present evidence that EPHX1 metabolizes the abundant endocannabinoid 2-arachidonoylglycerol (2-AG) to free arachidonic acid (AA) and glycerol. The EPHX1 metabolism of 2-AG was demonstrated using commercially available EPHX1 microsomes as well as PC-3 cells overexpressing EPHX1. Conversely, EPHX1 siRNA markedly reduced the EPHX1 expression and 2-AG metabolism in HepG2 cells and LNCaP cells. A selective EPHX1 inhibitor, 10-hydroxystearamide, inhibited 2-AG metabolism and hydrolysis of a well-known EPHX1 substrate, cis-stilbene oxide. Among the inhibitors studied, a serine hydrolase inhibitor, methoxy-arachidonyl fluorophosphate, was the most potent inhibitor of 2-AG metabolism by EPHX1 microsomes. These results demonstrate that 2-AG is an endogenous substrate for EPHX1, a potential role of EPHX1 in the endocannabinoid signaling and a new AA biosynthetic pathway.

Original languageEnglish (US)
Pages (from-to)2093-2102
Number of pages10
JournalJournal of lipid research
Issue number10
StatePublished - Oct 1 2014


  • Anandamide
  • Arachidonic acid
  • Prostate carcinoma cells

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology
  • Cell Biology


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