title: 4'-O-methylhonokiol increases levels of 2-arachidonoyl glycerol in mouse brain via selective inhibition of its COX-2-mediated oxygenation.
abstract: OBJECTIVE
  4'-O-methylhonokiol (MH) is a natural product showing anti-inflammatory, anti-osteoclastogenic, and neuroprotective effects. MH was reported to modulate cannabinoid CB2 receptors as an inverse agonist for cAMP production and an agonist for intracellular [Ca2+]. It was recently shown that MH inhibits cAMP formation via CB2 receptors. In this study, the exact modulation of MH on CB2 receptor activity was elucidated and its endocannabinoid substrate-specific inhibition (SSI) of cyclooxygenase-2 (COX-2) and CNS bioavailability are described for the first time.
  
  
  METHODS
  CB2 receptor modulation ([35S]GTPγS, cAMP, and β-arrestin) by MH was measured in hCB2-transfected CHO-K1 cells and native conditions (HL60 cells and mouse spleen). The COX-2 SSI was investigated in RAW264.7 cells and in Swiss albino mice by targeted metabolomics using LC-MS/MS.
  
  
  RESULTS
  MH is a CB2 receptor agonist and a potent COX-2 SSI. It induced partial agonism in both the [35S]GTPγS binding and β-arrestin recruitment assays while being a full agonist in the cAMP pathway. MH selectively inhibited PGE2 glycerol ester formation (over PGE2) in RAW264.7 cells and significantly increased the levels of 2-AG in mouse brain in a dose-dependent manner (3 to 20 mg kg(-1)) without affecting other metabolites. After 7 h from intraperitoneal (i.p.) injection, MH was quantified in significant amounts in the brain (corresponding to 200 to 300 nM).
  
  
  CONCLUSIONS
  LC-MS/MS quantification shows that MH is bioavailable to the brain and under condition of inflammation exerts significant indirect effects on 2-AG levels. The biphenyl scaffold might serve as valuable source of dual CB2 receptor modulators and COX-2 SSIs as demonstrated by additional MH analogs that show similar effects. The combination of CB2 agonism and COX-2 SSI offers a yet unexplored polypharmacology with expected synergistic effects in neuroinflammatory diseases, thus providing a rationale for the diverse neuroprotective effects reported for MH in animal models.
authors.affiliation: Institute of Biochemistry and Molecular Medicine, NCCR TransCure, University of Bern, Bühlstrasse 28, CH-3012, Bern, Switzerland. chicca@ibmm.unibe.ch.
authors.forename: Andrea
authors.initials: A
authors.lastname: Chicca
authors.affiliation: Institute of Biochemistry and Molecular Medicine, NCCR TransCure, University of Bern, Bühlstrasse 28, CH-3012, Bern, Switzerland. gachet@ibmm.unibe.ch.
authors.forename: Maria Salomé
authors.initials: MS
authors.lastname: Gachet
authors.affiliation: Institute of Biochemistry and Molecular Medicine, NCCR TransCure, University of Bern, Bühlstrasse 28, CH-3012, Bern, Switzerland. petrucci@ibmm.unibe.ch.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Petrucci
authors.affiliation: Institute of Zoology, Karl-Franzens-University Graz, Universitätsplatz 2, 8010, Graz, Austria. wolfgang.schuehly@uni-graz.at.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schuehly
authors.affiliation: Institute of Biochemistry and Molecular Medicine, NCCR TransCure, University of Bern, Bühlstrasse 28, CH-3012, Bern, Switzerland. charles@ibmm.unibe.ch.
authors.forename: Roch-Philippe
authors.initials: RP
authors.lastname: Charles
authors.affiliation: Institute of Biochemistry and Molecular Medicine, NCCR TransCure, University of Bern, Bühlstrasse 28, CH-3012, Bern, Switzerland. gertsch@ibmm.unibe.ch.
authors.forename: Jürg
authors.initials: J
authors.lastname: Gertsch
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001095:Arachidonic Acids / Q000378:metabolism* / Q000493:pharmacokinetics; D019390:Arrestins / Q000378:metabolism; D001713:Biphenyl Compounds / Q000494:pharmacology*; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D016466:CHO Cells; D002461:Cell Line, Transformed; D003412:Cricetulus; D000242:Cyclic AMP / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D063388:Endocannabinoids / Q000378:metabolism* / Q000493:pharmacokinetics; D005260:Female; D005989:Glycerides / Q000378:metabolism* / Q000493:pharmacokinetics; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000493:pharmacokinetics; D017705:Lignans / Q000494:pharmacology*; D008264:Macrophages; D051379:Mice; D012826:Silicone Elastomers / Q000493:pharmacokinetics; D013460:Sulfur Isotopes / Q000493:pharmacokinetics; D014316:Tritium / Q000493:pharmacokinetics; D000071557:beta-Arrestins
chemical_list: C542058:4-O-methylhonokiol; D000893:Anti-Inflammatory Agents; D001095:Arachidonic Acids; D019390:Arrestins; D001713:Biphenyl Compounds; D063388:Endocannabinoids; D005989:Glycerides; D017705:Lignans; D012826:Silicone Elastomers; D013460:Sulfur Isotopes; D000071557:beta-Arrestins; D014316:Tritium; C006194:aminoethyl-aminopropyl-trimethoxysilane; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C094503:glyceryl 2-arachidonate; D000242:Cyclic AMP; D051546:Cyclooxygenase 2