Structure and Physiological Activity of Glycolipids from Amphibias

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The structures of three ganglioside isolated from bullfrog (Rana catesbeiana) brain tissue have been established as disialosylgangliotetraosylceramide (I11^6NeuAclV^3NeuAc-GgOse_4Cer), trisialosvlgangliotetraosvlceramide (I11^6NeuAclV^3(NeuAc)_2-GgOse_4Cer), and tertasialosylgangliotetraosylceramide (I11^6(NeuAc)_2lV^3(NeuAc)_2-GgOse_4Cer) by NMR and mass spectral measurements. A similar distribution of these gangliosides was seen among hemisphere, dienecephalon and mixed tissue from the optic lobe, cerebellum and medulla oblongata of the brain. The brain tissues of Rana nigromaculata and Rhacophorus arboreus also included the same gangliosides as those of bullfrog.On the other hand, twelve cerebrosides were isolated from the brain tissues of the bullfrog and they were characterized as 1-omicron-beta-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> and C_<24:1> acids 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 chirality of the benzoate-benzamide derivatives. Furthermore, the chiral center 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 cerebroside was seen among the hemisphere, dienecephalon and mixed tissue from the optic lobe, cerebellum and medulla oblongata of the brain.