In our continuing research on biologically active glycosphingolipids (GSLs) from echinoderms, a series of studies on the isolation and structural elucidation of the GSLs from sea cucumber species have been performed in our laboratory. [2][3][4][5][6][7][8][9][10][11] In the study of the GSLs of the sea cucumber Holothuria pervicax, we reported the isolation and structure of ten glucocerebrosides revealing a very close resemblance in structure.9) However, all these compounds still exist as a mixture of regio-isomers for terminal methyl groups in the side chain of the long-chain base (LCB) moiety, namely a mixture of iso and ante-iso isomers as shown in Fig. 1. Continuing the previous studies, the separation of the mixture of the regio-isomers was conducted. In this paper, we report on the isolation of an ante-iso type regio-isomer of glucocerebroside from its parent glucocerebroside molecular species HLC-2, an abundant compound obtained from the whole bodies of the sea cucumber Holothuria leucospilota (Nisekuronamako in Japanese). 12)The less polar lipid fraction, which was obtained from the chloroform/methanol extract of the whole bodies of H. leucospilota, was subjected to repeated silica gel column chromatography to give three cerebroside molecular species, HLC-1, HLC-2, and HLC-3, each showing a single spot on silica gel thin-layer chromatography (TLC).In the IR and positive-ion FAB mass spectra of HLC-1, HLC-2, and HLC-3, strong hydroxy and amide absorptions and a series of molecular ion peaks are observed. Their 13 C-NMR spectra (Fig. 1, Table 1) exhibit the characteristic signals of a sphingosine-type b-glucocerebroside possessing an unsubstituted fatty acid (HLC-1), a sphingosine-type b-glucocerebroside possessing a 2-hydroxy fatty acid (HLC-2), and a phytosphingosine-type b-glucocerebroside possessing a 2-hydroxy fatty acid (HLC-3), respectively. Therefore, they are suggested to be the molecular species of three typical types of glucocerebrosides. Their structures shown in Fig. 1 were characterized by comparison of their 13 C-NMR spectral data with those of known glucocerebrosides 2-4) 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 LCB, as shown in Fig. 2 and Experimental. The geometry (Z) of the double bond in the unsaturated fatty acyl moiety of HLC-1-HLC-3 was determined from the d value (27.4, 27.5) of the allylic carbon atoms obtained from their 1 H-detected heteronuclear multiple-bond connectivity (HMBC) spectra (Fig. 3) ; 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan: and b Department of Medical Electronics Engineering, Faculty of Engineering, Towa University; 1-1-1 Chikusigaoka, Minamiku, Fukuoka 815-0036, Japan. Received February 14, 2005; accepted March 22, 2005 An ante-iso type regio-isomer on the long chain base moiety of a glucocerebroside, HLC-2-A, has been isolated from its parent glucocerebroside molecular species HLC-2 composed of ...

In our continuing research on biologically active glycosphingolipids (GSLs) from echinoderms, a series of studies on the isolation and structural elucidation of the GSLs from sea cucumber species have been performed in our laboratory. [2][3][4][5][6][7][8][9][10][11][12] In the preceding paper, we reported the isolation of a sphingosine-type glucocerebroside (HLC-2-A in Chart 1) with ante-iso type side chain of the long-chain base (LCB) moiety from the whole bodies of the sea cucumber Holothuria leucospilota (Nisekuronamako in Japanese). 1)However, the absolute configuration of the branched methyl group (C 14 -Me) in the ante-iso moiety has not yet been determined. In this paper, we report determination of the absolute configuration of the branched methyl group of HLC-2-A.Since study on the cerebroside itself was regarded as difficult, we focused on a fragment which included the ante-iso moiety from the parent cerebroside. Trimethylsilylation followed by ozone oxidation of HLC-2-A gave C 13 -fragment (1) which was released from the cerebroside by the fission of C4-C5 bond. Compound 1 was converted to alcohol (natural 2) by reduction with NaBH 4 . The absolute configuration of natural 2, 10-methyl dodecanol, was elucidated by comparison with synthetic optically active 2 as follows (Chart 1).One of the primary alcohols of 1,4-butanediol (3) was protected by TBDMS ether to give 4. The remaining hydroxy group of 4 was converted to bromide with CBr 4 under standard conditions, producing 5. The triphenylphosphonium salt (6) was synthesized from 5 with elimination of the TBDMS group using the usual process. The Wittig reaction with 6 and (S)-6-methyl octanal (8), which was synthesized from commercially-available (S)-6-methyl octanol (7) by PCC oxidation, yielded (S)-10-methyl dodecenol (9). Finally, hydrogenation of 9 with Pd-C gave (S)-10-methyl dodecanol (synthetic 2). 13)Comparison of the optical rotations of natural 2 (ϩ50.3°) and synthetic 2 (ϩ53.3°) suggests the former is also (S)-10-methyl dodecanol. Furthermore, their ORD spectra are identical. Therefore, the branched methyl group, C 14 -Me, in the ante-iso moiety of HLC-2-A must be S configuration as shown in Chart 1.The present study is, to the best of our knowledge, the first regarding determination of the absolute configuration of branched methyl group in the ante-iso type of side chain of sphingolipids and thus worthy of noting. ExperimentalOptical rotations were measured with a Jasco Dip-370 digital polarimeter at 25°C. ORD spectra were taken with a Jasco J-720W spectropolarimeter at The absolute configuration of the branched methyl group in ante-iso type side chain moiety on the long chain base of glucocerebroside, HLC-2-A, which was isolated from the sea cucumber Holothuria leucospilota was determined. Oxidation of the glucocerebroside with ozone afforded C 13 -fragment including the ante-iso moiety. The optically active C 13 -fragment was synthesized asymmetrically by using the Wittig reaction from chiral synton for comparison with the natural fragment.

Lipids U 0750Constituents of Holothuroidea. Part 15. Isolation of Ante-iso Type Regioisomer on Long Chain Base Moiety of Glucocerebroside from the Sea Cucumber Holothuria leucospilota. -The β-D-glucopyranosyl ceramide (I) is isolated with the help of RP(C30)-HPLC from a mixture of regioisomeric glucocerebrosides obtained from a sea cucumber species. -(YAMADA, K.; WADA, N.; ONAKA, H.; MATSUBARA, R.; ISOBE, R.; INAGAKI, M.; HIGUCHI*, R.; Chem. Pharm. Bull. 53 (2005) 7, 788-791; Fac. Pharm. Sci., Kyushu Univ., Fukuoka 812, Japan; Eng.) -H. Haber 50-190

Lipids U 0750 Constituents of Holothuroidae. Part 16. Determination of Absolute Configuration of the Branched Methyl Group in Ante-iso Type Side Chain Moiety on Long Chain Base of Glucocerebroside from the Sea Cucumber Holothuria leucospilota. -(YAMADA, K.; ONAKA, H.; TANAKA, M.; INAGAKI, M.; HIGUCHI*, R.; Chem. Pharm. Bull. 53 (2005) 10, 1333-1334; Fac. Pharm. Sci., Kyushu Univ., Fukuoka 812, Japan; Eng.) -C. Oppel