Ethanolamine plasmalogens, aldehydes

Also, the primary amine moities of polar lipids catalyze the aldol condensation of Cm-Cig aldehydes resulting from plasmalogen hydrolysis, thus forming a,3-unsaturated aldehydes (l2t). Phosphatidyl ethanolamine reacted with propanal and n-hexanal forming phosphatidyl l-(2-hydroxyethyl)-2-ethyl-3,5-dimethyl pyridinium, and phosphatidyl-1-(2-hydroxy ethyl)-2-hexyl-3,5-dipentyl pyridinium, respectively (125). The peridinium ring is formed by the reaction between one mole of amino-N of phosphatidyl ethanolamine and three moles of n-alkanals. The same reaction took place in the synthesis of substituted pyridines by condensation of carbonyl compounds with ammonia (126, 127). 

The a,jS-unsaturated fatty ether is an aldehydogenie group because its hydrolysis releases an a -unsaturated primary alcohol that readily tautomerizes to an aldehyde. Choline, ethanolamine, and serine plasmalogens are found in cardiac and skeletal muscle, brain, and liver. The biosynthesis of phosphatidylethanolamine is shown in Figure 19-5. 

The aldehydes, which have been isolated from these plasmalogens, are predominantly saturated and monounsaturated aldehydes (16 0, 18 0, 18 1, 18 1 ). In contrast, the fatty acids linked to the /9-C-atom in choline plasmalogens are mostly Cig-unsaturated fatty acids, no C22-polyenoic acids have been observed (Klenk et al. 1957 Debuch 1956). Heart muscle mainly contains choline plasmalogens, whereas brain tissue has ethanolamine and serine plasmalogens (Klenk et al. 1951 Ansell et al. 1956). These are localized in brain white matter (Webster 1960). Previous attempts to separate diacylglycerophosphoryl choline or -ethanolamine from the respective plasmalogens were unsuccessful. 

In vivo 94% of the aldehyde could be recovered as the alkenyl ether residue in plasmalogens. The water-soluble ethanolamine is... 

---