The preparation of Tay-Sachs ganglioside specifically labeled in either the N-acetylneuraminosyl or N-acetylgalactosaminyl portion of the molecule

Synthesis of Benzophenone-Containing Analogues of Phosphatidylcholine

As part of a collaborative study of cellular efflux of cholesterol and phospholipids, photoactivable analogues 4-8 of phosphatidylcholine (PC) having benzophenone groups in the choline moiety and at the end of the C2 and C1 alkyl chains have been synthesized. The efficient preparation via Suzuki coupling of the appropriate long-chain benzophenone-containing carboxylic acid and alcohol and their incorporation by adaptation of known approaches into the acyl- and ether-linked PC analogues 6-8 are described. Development of a method for radiolabeling these PC analogues, via hydrogenation of a double bond in modified side chains, is also described.

Quantitation of choline and its metabolites in tissues and foods by liquid chromatography/electrospray ionization-isotope dilution mass spectrometry

Choline is important for normal membrane function, acetylcholine synthesis, lipid transport, and methyl metabolism. The U.S. National Academy of Sciences recently set requirements for choline in the human diet. In tissues and foods, there are multiple choline compounds that contribute to choline content. Betaine, a derivative of choline, is also important because of its role in donation of methyl groups to homocysteine to form methionine. Radioisotopic, high-pressure liquid chromatography, and gas chromatography/isotope dilution mass spectrometry (GC/IDMS) methods are available for measurement of choline. However, these existing methods are cumbersome and time-consuming, and none measures all of the compounds of interest. In this study, we describe a new method for quantitation of choline, betaine, acetylcholine, glycerophosphocholine, cytidine diphosphocholine, phosphocholine, phosphatidylcholine, and sphingomyelin in liver, plasma, various foods, and brain using liquid chromatography/electrospray ionization-isotope dilution mass spectrometry (LC/ESI-IDMS). Choline compounds were extracted by and partitioned into organic and aqueous phases using methanol and chloroform and analyzed directly by LC/ESI-IDMS without the need for isolation and derivatization of each compound separately as was required by the GC/IDMS method. The new LC/ESI-IDMS method was validated using the existing published GC/IDMS method.