Cerebrosides of frog brain. Structure of the ceramide part of the cerebrosides

Abstract

Twelve cerebrosides were isolated from the brain tissues of the bullfrog (Rana catesbeiana) and they were characterised as 1-o-β-D-galactopyranosyl ceramides. On the basis of chemical and spectral evidence, the ceramide parts of six of them were found to be composed of a sphingosine as a long-chain base and six fatty acids consisting of C_18:0, C_22:1, C_24:1 and their 2-hydroxy derivatives. The ceramide parts of the others were found to be composed of a dihydrosphingosine and the six fatty acids. The configurations at C-2 and C-3 of the two long-chain bases were determined to be S and R, respectively, on the basis of the NMR spectra of their acetates and the exciton chiralities of the benzoate-benzamide derivatives. Further, the chiral centre of the three 2-hydroxy fatty acids was determined to be R in all cases by means of CD measurements. A different distribution of the cerebrosides was seen among the hemisphere, diencephalon and mixed tissue from the optic lobe, cerebellum and medulla oblongata of the brain.