Analysis of endocannabinoids by Ag+ coordination tandem mass spectrometry.
The neutral arachidonic acid derivatives N-arachidonylethanolamide (anandamide or AEA) and 2-arachidonylglycerol (2-AG) have been identified as endogenous ligands for the cannabinoid receptors. Quantitation of these endocannabinoids from various tissues has been shown to be essential in the elucidation of cannabinoid-mediated processes in vivo. Here, we describe a novel method for the detection and quantitation of AEA and 2-AG from mammalian tissue. We exploit the ability of silver cation to bind to the polyunsaturated arachidonate backbone of both molecules to form the charged species [M+Ag](+). These complexes are amenable to liquid chromatography-electrospray ionization-tandem mass spectrometry analysis, resulting in the simple and specific quantitation of AEA and 2-AG. The limits of detection of 2-AG and AEA are 13 and 14fmol, respectively, on-column. This method provides an alternative to existing methods, which employ derivation and/or selected ion monitoring (when mass spectrometric detection is used), and may facilitate the understanding of the physiological roles of this new class of compounds.
Kingsley
Philip J
PJ
Department of Biochemistry and Chemistry, Center in Molecular Toxicology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
Marnett
Lawrence J
LJ
D000818:Animals; D001923:Brain Chemistry; D063385:Cannabinoid Receptor Modulators; D002186:Cannabinoids / Q000032:analysis* / Q000737:chemistry; D002853:Chromatography, Liquid; D063388:Endocannabinoids; D005231:Fatty Acids, Unsaturated / Q000032:analysis* / Q000737:chemistry; D008297:Male; D051379:Mice; D015394:Molecular Structure; D012680:Sensitivity and Specificity; D012834:Silver / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
D063385:Cannabinoid Receptor Modulators; D002186:Cannabinoids; D063388:Endocannabinoids; D005231:Fatty Acids, Unsaturated; D012834:Silver