Quantitative analysis and comparison of the physical properties of O-alkyl and S-alkyl monoethers of glycerol

A homologous series (C(10), C(12), C(14), C(16), C(18)) of synthetic O-alkyl and S-alkyl ethers of glycerol was analyzed by gas-liquid chromatography (GLC) and thin-layer chromatography (TLC), and examined by IR and n.m.r. spectroscopy; the physical properties of the O-alkyl and S-alkyl ethers were compared. Isopropylidene derivatives of the glycerol ethers and thioethers were quantitatively analyzed by GLC on polar and nonpolar liquid phases. On a medium polar liquid phase (ethylene glycol succinate), mixtures of the O-alkyl and S-alkyl ethers were completely resolved. Isopropylidene derivatives of glycerol ethers and of thioethers could be separated as classes (though not into individual homologues) by TLC. O-hexadecyl and S-hexadecyl ethers of glycerol are easily distinguished by IR and n.m.r. spectroscopy.     

1-O-alkyl-2-N-methylcarbamyl-glycerophosphocholine: a biologically potent, non-metabolizable analog of platelet-activating factor

We prepared unlabeled and 3H-labeled analogs of platelet-activating factor (PAF) containing a N-methylcarbamyl residue at the sn-2 position. PAF and its methylcarbamyl analog competed for binding to high affinity receptors on human polymorphonuclear neutrophils; their respective dissociation constants for these receptors were 0.2 and 1.1 nM. The binding affinities of the two analogs correlated precisely with their capacities to stimulate neutrophil degranulation responses. Unlike PAF, however, the methylcarbamyl analog completely resisted metabolic inactivation by neutrophils and by human sera. Thus, these compounds' biological potencies are determined predominantly by receptor binding: cellular metabolism of the ligands neither contributes to nor appreciably limits their stimulating actions.     

Membrane lipid modifications: Biosynthesis and identification of phosphatidyl-N-methyl-N-isopropylethanolamine in rat liver microsomes

In previous studies on the modification of polar head groups of membrane phospholipids with the unnatural base analog, $\text{N-}\text{isopropylethanolamine}$, we reported an unidentified phospholipid in addition to $\text{phosphatidyl}\text{-N-}\text{isopropylethanolamine}$ in the various membrane fractions of rat liver. The structure of this phospholipid has now been identified as $\text{phosphatidyl}\text{-N-}\text{methyl}\text{-N-}\text{isopropylethanolamine}$ by nuclear magnetic resonance spectroscopy, and by chromatographic and enzymic analysis. In addition, we found that when rats were injected intraperitoneally with the $\text{N-}\text{methyl}\text{-N-}\text{isopropylethanolamine}$, 19% of teh liver microsomal phospholipid was $\text{phosphatidyl}\text{-N-}\text{methyl}\text{-N-}\text{isopropylethanolamine}$.