Cerebrosides from a Far‐Eastern Glass Sponge Aulosaccus sp.

Abstract

Nine new cerebrosides 1a-d, 2a, 2b, 3a-c were found in the extract of a Far-Eastern glass sponge Aulosaccus sp. (class Hexactinellida). These β-D-glucopyranosyl-(1 → 1)-ceramides contain sphingoid bases (2S,3S,4R,11Z)-2-aminoeicos-11-ene-1,3,4-triol (in 1a-d), (2S,3S,4R,13Z)-2-aminoeicos-13-ene-1,3,4-triol (in 2a, b) and (2S,3S,4R,13S*,14R*)-2-amino-13,14-methylene-eicosane-1,3,4-triol (in 3a-c), which are N-acylated by (2R,15Z)-2-hydroxydocos-15-enoic (in 1a, 2a, 3a), (2R,16Z)-2-hydroxytricos-16-enoic (in 1b, 2b, 3b), (2R,17Z)-2-hydroxytetracos-17-enoic (in 1d) and (2R)-2-hydroxydocosanoic (in 1c, 3c) acids. The monoenoic and cyclopropane-containing sphingoid bases of compounds 1a-d, 2a, 2b, 3a-c have not been found previously in any sphingolipids. The structures of the cerebrosides were elucidated on the basis of (1)H-, (13)C-NMR spectroscopy, mass spectrometry, optical rotation data and chemical transformations. A simplified method for the assignment of the absolute configuration of 2-hydroxy fatty acids by GC analysis of their (2R)- and (2S)-oct-2-yl esters was proposed.

Fatty Acids from a Glass Sponge Aulosaccus sp. Occurrence of New Cyclopropane‐Containing and Methyl‐Branched Acids

“…1 H-NMR, 1 H-1 H-COSY, HSQC and HMBC spectra (in CDCl 3 ) were recorded on Bruker Avance III HD 500 and Bruker Avance III 700 spectrometers (Bruker BioSpin, Germany) at 500 and 700 MHz with TMS as an internal standard. GC-MS analyses were carried out on a Hewlett Packard HP6890 GC System (Hewlett Packard Company, USA) with an HP-5MS (J&W Scientific, USA) capillary column (30.0 m × 0.25 mm), helium as the carrier gas, and 70 eV ionizing potential.…”

“…A sample of the sponge, belonging to the genus Aulosaccus (phylum Porifera, class Hexactinellida, order Lyssacinosida, family Rossellidae), 930 g (wet weight), was collected in July, 2011, by dredging (with small Sigsbi trail) from 505 m depth near Iturup Island (Kuril Islands, 45°01,5N, 147°00,3E) during a cruise onboard the r/v "Academik Oparin" [1].…”

“…The collected sponge was frozen, stored at −15 °C, then cut and extracted with EtOH at room temperature. A mixture, containing cerebrosides, FA and other compounds (895 mg), was isolated from the EtOH extract as described in our previous study [1]. The separation of this mixture by column chromatography on silica gel gave 38 mg of free FA eluted with AcOEt.…”

“…Free FA were methylated or ethylated, using N-nitroso-N-methylurea or N-nitroso-N-ethylurea. Some FA methyl(ethyl) esters and pyrrolidides were converted into DMDS adducts or were hydrogenated over Pt in AcOH as described previously [1].…”

“…Recently, we elucidated the structures of new cerebrosides from a Far-Eastern glass sponge Aulosaccus sp. (from the north-west Pacific) [1,2]. Their trihydroxy sphingoid bases with unusual double bonds, cyclopropane ring or methyl branches have not been found in other sphingolipids.…”