Metabolism of Sphingosine Bases, IV. 2-Amino-1-hydroxyoctadecane-3-one (3-oxodihydrosphingosine), the Common Intermediate in the Biosynthesis of Dihydrosphingosine and Sphingosine and in the Degradation of Dihydrosphingosine

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Abstract
The metabolism of [3-14C]3-oxodihydro-sphingosine ([3-14C]2-amino-l-hydroxyoctadecan-3-one) has been studied in the rat. This is degraded to palmitic acid and CO2 and ethanolamine at a rate comparable or even more rapid than observed for [3-14C] dihydrosphingosine, yielding the same degradation products in similar proportions. The pattern of incorporation of the resulting palmitic acid and its elongation product stearic acid, into ester- and sphingolipids also resembled that after administration of dihydrosphingosine. Experiments indicated that the 1st step in the degradation of dihydrosphingosine is the dehydrogenation of the secondary alcohol group at C-3 to 3-oxodihydrosphingosine. [3-14c]3-oxodihy-drosphingosine was transformed to [3-14C] dihydrosphingosine and sphingosine, the latter being the main product. The 2 bases are incorporated into ceramide and sphingomyelin, the only 2 labeled sphingolipids in the rat liver. No free or bound 3-oxodihydrosphingosine was recovered under these experimental conditions. The key function of 3-oxodihydrosphingosine in the biosynthesis is discussed.