No-carrier-added carbon-11-labeled sn-1,2- and sn-1,3-diacylglycerols by [11C]propyl ketene method.
This article describes the preparation of sn-1,2-[11C]diacylglycerols and sn-1,3-[11C]diacylglycerols by a no-carrier-added reaction based on a labeling method using [1-11C]propyl ketene, which is one of the most potent acylating agents. [1-11C]Propyl ketene was produced by pyrolytic decomposition of [1-11C]butyric acid and was trapped in pyridine containing L-alpha-palmitoyl-lysophosphatidylcholine, producing L-alpha-palmitoyl-2-[1-11C]butyryl-sn-glycero-3-phosphorylcholine. We adopted an enzymatic reaction to remove the phosphorylcholine, in which L-alpha-palmitoyl-2-[1-11C]butyryl-sn-glycero-3-phosphorylcholine was incubated with phospholipase C, hydrolyzing to produce 1-palmitoyl-sn-2-[1-11C]butyrylglycerol. Total synthesis time was about 50 minutes and the specific activity was estimated at 93 GBq/mumol (2.5 Ci/mumol) at end of synthesis. Radiochemical yield was 3.8% based on the trapped 11CO2. sn-1,3-[11C]Diacylglycerol was also synthesized by [1-11C]propyl ketene reaction with 1-palmitoyl-sn-glycerol in a single procedure. The regional brain tissue radioactivities obtained in sn-1,2-[11C]diacylglycerol were higher than those of sn-1,3-[11C]diacylglycerol, and the regional values varied widely. In autoradiography of brain slices from conscious rats, sn-1,2-[11C]diacylglycerol incorporation sites were discretely localized, especially in the amygdala, cerebral cortex, and hippocampus, suggesting that intensive neuronal processing occurred in these areas on the basis of phosphatidylinositol turnover.
Imahori
Y
Y
Department of Neurosurgery, Kyoto Prefectural University of Medicine, Japan.
Fujii
R
R
Ueda
S
S
Ido
T
T
Nishino
H
H
Moriyama
Y
Y
Yamamoto
Y L
YL
Nakahashi
H
H
D000215:Acylation; D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000000981:diagnostic imaging*; D002250:Carbon Radioisotopes; D004075:Diglycerides; D005030:Ethylenes; D007553:Isotope Labeling / Q000379:methods; D007659:Ketones; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D004075:Diglycerides; D005030:Ethylenes; D007659:Ketones; C008223:ketene