Identification and quantitation of lipid-bound short-chain diols

Naturally-occurring diol lipids. XI. Diol lipids of rat liver. Quantitation and structural characteristics of neutral lipids and phospholipids derived from ethanediol, propanediols, and butanediols

“…The hydroxylipids produced through phospholipase C hydrolysis of individual phospholipid fractions (3a-3d), the native hydroxylipids (2a), and the nonpolar lipid fraction (1) were degraded, and their constituent diols were derivatized, as shown in Scheme I Methanolysis in the presence of anhydrous barium hydroxide completely cleaves ester functions at polyhydric moieties, including those linked to tertiary hydroxy groups. Boron trifluoride accomplishes conversion of the barium salts of fatty acids to methyl esters and, at the same time, cleaves alk-l-enyl ethers without the formation of artifacts ( Schupp and Baumann, 1973). Alkyl diol ethers would not be cleaved and accounted for using this procedure.…”

“…The procedure for the acetalation of polyhydric alcohols with long-chain aldehyde catalyzed by p-toluenesulfonic acid under azeotropic removal of water with benzene, a method proven effective for synthetic mixtures (Schupp and Baumann, 1973), required some modification to assure reproducible analyses of diol lipids in natural lipid fractions, particularly in the presence of cholesterol. Condensation of the polyols in the transmethylation mixture with hexadecanal is brought about at room temperature by addition of anhydrous p-toluenesulfonic acid.…”

“…Cyclic acetals used as standards were prepared by acidcatalyzed condensation of short-chain diols with hexadecanal (Schupp and Baumann, 1973). Internal lipid standards derived from perdeuterated ethanediol were synthesized as follows: [1,1,2,2-2H] Ethanediol monohexadecanoate and [l,l,2,2,-2H]ethanediol dihexadecanoate were prepared by acylation of [l,l,2,2-2H]ethanediol (99.9%; Merck Co., Rahway, N.J.) with hexadecanoyl chloride (Baer, 1953;Baumann et al, 1967).…”

“…Individual diol lipids were quantified as the respective diol acetals by glc relative to the amount of 2-pentadecyl-1.3-[4,4,5,5-2H]dioxolane present in the ethanediol acetal fraction. The ratio of deuterated (from internal standard) to nondeuterated ethanediol cyclic acetals was determined by glc-ms on the basis of the intensities of the prominent 1.3-dioxolane ions (65% of total ionization) at mje 77 and m/e 73 for the deuterated and nondeuterated species, respectively (Schupp and Baumann, 1973;Baumann et al, 1973). The amounts of individual acetals were finally corrected for small amounts of "background" acetals as determined through control analyses on reagents only.…”