A Methodology for Radiolabeling of the Endocannabinoid 2-Arachidonoylglycerol (2-AG)
作者:Richard I. Duclos、Meghan Johnston、Subramanian K. Vadivel、Alexandros Makriyannis、Sherrye T. Glaser、S. John Gatley
DOI:10.1021/jo102277q
日期:2011.4.1
The metabolic intermediate and endocannabinoid signaling lipid 2-arachidonoylglycerol (2-AG) has not been readily labeled, primarily because of its instability toward rearrangement. We now detail a synthetic method that easily gives tritiated 2-AG from [5,6,8,9,11,12,14,15-H-3(N)]arachidonic acid in two steps. We utilized a short chain 1,3-diacylglycerol and proceeded through the "structured lipid" [5 '',6 '',8 '',9 '',11 '',12 '', 14 '',15 ''-H-3(N)]2-arachidonoyl-1,3-dibutyrylglycerol, a triacylglycerol that was conveniently deprotected in ethanol with acrylic beads containing Candida antarctica lipase B to give [5 '',6 '',8 '',9 '',11 '',12 '',14 '',15 ''-H-3(N)]2-arachidonoylglycerol ([H-3]2-AG). The flash chromatographic separation necessary to isolate the labeled 2'-acylglycerol [H-3]2-AG resulted in only 4% of the rearrangement byproducts that have been a particular problem with previous methodologies. This reliable "kit" method to prepare the radiolabeled endocannabinoid as needed gave tritiated 2-arachidonoylglycerol [H-3](2)-AG with a specific activity of 200 Ci/mmol for enzyme assays, metabolic studies, and tissue imaging. It has been run on unlabeled materials on over 10 mg scales and should be generally applicable to other 2-acylglycerols.