Constituents of Holothuroideae, V. Isolation and Structure of Cerebrosides from the Sea Cucumber Pentacta australis

Abstract

Four new cerebrosides, PA-0-1, PA-0-5, PA-2-5 and PA-2-6, rebroside CE-2cr1l obtained from the related sea cucumber were isolated from the two cerebroside mixtures, PA-0 and Cucumaria echinata of the same family. Reversed-phase PA-2, obtained from the less polar fraction of the methanol HPLC was effective in isolating these cerebrosides, showing extract of the sea cucumber Pentacta australis. The structures the very close similarity of their structures. An analysis of of these cerebrosides were determined on the basis of chemi-the mass spectrum of the dimethyl disulfide derivatives of cal and spectroscopic evidence. Another cerebroside, PA-1-cerebrosides was also useful for the determination of the 4, isolated in a pure state from a different cerebroside mix-double-bond position in the sea cucumber cerebroside.ture PA-1, was found to be identical with the known glucoceAs described in the preceding paper"], three sphingosinetype glucocerebrosides, CE-2b, CE-2c and CE-2d, were isolated from a cerebroside mixture, which was obtained from the less polar fraction of the methanol extract of the sea cucumber Cucumaria echinata, and characterized.In continuation of the preceding studies on the sea cucumber C. echinata, the isolation and structure determination of the homogeneous cerebrosides from the related sea cucumber Pentacta australis (Gokakukinko in Japansese) of the same family are conducted due to the considerable interest and importance attached to the determination of the composition of the mixture of glycosphingolipids, and in the hope of discovering the biologically active compounds from marine natural products.In ref.L2] we have reported o n the isolation and structure determination of the biologically active triterpenoid oligoglycosides isolated from the whole bodies of l? australis. In this paper, the isolation and structure determination of four new and one known cerebrosides from the whole bodies of l? australis are described.The chloroform soluble part, which is obtained from the methanol extract of the whole bodies of P australis, is separated by silica gel column chromatography to give three compounds, PA-0, PA-1 and PA-2, showing a single spot on normal-phase (silica gel) TLC.are observed (Scheme 1 and Table 1). Therefore, PA-0 must be a mixture of sphingosine-type cerebrosides composed of fatty acid and P-glucopyranose moieties. Furthermore, PA-0 is presumed to have type of fatty acids and ante-isd3I type of long-chain bases, mainly, because the carbon signals for the terminal methyl groups are observed at 6 = 14.3 (normal form), 6 = 11.5 and 19.4 (ante-iso form) in the 13C-NMR spectrum of PA-0 (Scheme 1 and Table 1). Before separation of the mixture PA-0 into individual cerebrosides, the fatty acid constituents and the stereochemistry of the long-chain base of the cerebroside mixture are investigated. the IR spectrum and a series of molecular ion peaks in the C According to the Gaver-Sweeley methodl41, PA-0 is methanolyzed with methanolic hydrochloric acid to yield a mix-

Constituents of Holothuroidea. 12. Isolation and Structure of Glucocerebrosides from the Sea Cucumber Holothuria pervicax.

“…[2][3][4][5][6][7][8] In the study of the GSLs of the sea cucumber Holothuria pervicax (Torafunamako in Japanese), we reported the isolation and structure of four new ganglioside molecular species. 5,7) Continuing the preceding studies, the isolation and characterization of cerebrosides from H. pervicax was conducted.…”

“…Their structures shown in Fig. 1 were characterized by comparison of their 13 C-NMR spectral data with those of known glucocerebrosides [2][3][4] hitherto obtained, and by means of the results of their chemical degradations, namely methanolysis followed by the GC-MS analysis of the methanolysis products, fatty acid methyl ester (FAM) and long-chain base (LCB), as shown in Fig. 2 and the Experimental section.…”

Constituents of Holothuroidea, 13. Structure of Neuritogenic Active Ganglioside Molecular Species from the Sea Cucumber Stichopus chloronotus.

“…Furthermore, the relative stereochemistry of the ceramide moiety was presumed to be (2S, 3R, 4E, 2ЈR), since the aforementioned 13 C-NMR signals attributable to C-1, 2, 3, 4, 5, and 2Ј of SCG-1 were in good agreement with those of the known sphingosine-type glucocerebroside molecular species 2) with (2S, 3R, 4E, 2ЈR) configurations obtained from another sea cucumber. The structure of the disaccharide moiety of SCG-1 was established as follows.…”

“…[2][3][4][5][6][7] Continuing the previous studies, our search for the biologically active ganglioside from the sea cucumber Stichopus chloronotus (shikakunamako in Japanese) has led to the isolation of three ganglioside molecular species designated SCG-1, SCG-2, and SCG-3. In this paper, we report on the isolation and characterization of these three gangliosides from the body walls of S. chloronotus.…”

“…Its 13 C-NMR spectrum exhibited the characteristic signals of a sphingosine-type ceramide, 2,3) possessing a 2-hydroxy fatty acid and a sugar moiety at C-1 [d: 70.2 (C-1), 54.1 (C-2), 72.3 (C-3), 131.4 (C-4), 132.9 (C-5), 175.7 (C-1Ј), and 72.2 (C-2Ј)]. The spectrum also revealed signals attributed to two anomeric carbons at d: 101.1 and 105.2, one of which (d: 101.1) was a quaternary carbon signal, indicating the existence of one sialic acid function.…”