Dephosphorylation and benzoylation reactions occurring in the benzoolysis of diacyl-, alkylacyl-, alk-1-enylacyl-, and acyl-lyso-glycerophosphocholines.

Series of benzoolysis experiments with 1,2-dipalmitoyl glycerophosphocholine (GPC), 1-palmitoyl-2-lyso GPC, and 1-O-hexadecenyl-2-oleoyl GPC, as well as a few experiments with 1-oleoyl-2-acetyl GPC and 1-O-hexadecyl-2-acetyl GPC are reported. The results are used to present a consistent picture of the various dephosphorylation and benzoylation reactions occurring in molten benzoic anhydride.

Benzoolysis of diacylglycerophosphocholines: dephosphorylation and sequential formation of isomeric reaction products.

Benzoolysis experiments are reported in which diacylglycerophosphocholine is heated at 100 degrees C with benzoic anhydride for variable periods of time. It is shown that more than 90% of the phospholipid is dephosphorylated after 5 h of heating. Lipid extracts of the reaction mixture contained 1,2- and 1,3-diacylglycerobenzoate and 1,2- and 1,3-diacylglycerol in nearly constant isomer ratios of about 3:1 and 1:2, respectively, independent of the heating and extraction time.

Quantitation of the diacyl, alkylacyl, and alk-1-enylacyl subclasses of choline glycerophospholipids by chemical dephosphorylation and benzoylation.

A method for the determination of the relative amounts of the diacyl, alkylacyl, and alk-1-enylacyl subclasses of choline glycerophospholipids by benzoolysis is described. The procedure consists of simply heating the phospholipid with benzoic anhydride in the presence of boric acid for 5 h at 100 degrees C, followed by reaction with 4-dimethylaminopyridine for 2 h at room temperature and HPLC analysis of the lipidic products formed. With model compounds of the three subclasses it is shown that diacyl- and alkylacylglycerophosphocholines are completely dephosphorylated by this procedure, yielding quantitatively the corresponding diacyl- and alkylacylglycerobenzoates.

Investigation of two new [99mTc]Tc-HEDP preparations that can be expected to give a better lesion-to-normal-bone uptake ratio when used as bone scanning agents.

Two new potential bone scanning agents have been prepared and characterized. One of the agents, Tc(Sn,pH 12)-HEDP, is prepared at pH 12 (and subsequently neutralized). The other agent, Tc(Fe)-HEDP, is prepared by reducing [99mTc]TcO4- by a mixture of Fe(II) and Sn(II).