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

Abstract

In order to identify new structures, the free fatty acids from an extract of a glass sponge Aulosaccus sp. (from the north-west Pacific) belonging to one of the least chemically investigated classes (Hexactinellida), were fractionated by RP-HPLC and analyzed by NMR spectroscopy and GC-MS of their pyrrolidine derivatives, methyl(ethyl) esters and their dimethyl disulfide adducts. One hundred and twenty-three C-C acids (including nine new compounds) were detected, one hundred and ten of these compounds have not been found previously in glass sponges. The levels of common methylene-interrupted polyenes, monoenes of the (n-7) family and less common branched-chain components proved to be high. New acids were shown to be 5,13-dimethyl-tetradec-4-enoic, cis-10,11-methylene-heptadecanoic, 10,12-dimethyl-octadecanoic, cis-12,13-methylene-nonadecanoic, (14E)-13-methyl-eicos-14-enoic, 19-methyl-eicos-13-enoic, cis-20,21-methylene-heptacosanoic, 27-methyl-octacos-21-enoic and (22Z)-nonacos-22-enoic. Some important mass spectrometric characteristics of pyrrolidides of homologous cyclopropane fatty acids are reported and discussed.

Analysis of the Configuration of an Isolated Double Bond in Some Lipids by Selective Homonuclear Decoupling

“…Chemicals: Methyl oleate (9-cis-octadecenoate; Fluka Chemie AG), elaidate (9-trans-octadecenoate; Sigma-Aldrich), palmitoleate (9cis-hexadecenoate), palmitelaidate (9-trans-hexadecenoate; Gasukuro Kogyo Inc. Japan), 15-cis-(2R)-2-hydroxydocosenoate, 16-cis-(2R)-2-acetyloxytricosenoate [11], oleic (9-cis-octadecenoic acid; Sigma), nervonic (15-cis-tetracosenoic; Sigma-Aldrich), 5cis,9-cis,22-cis-nonacosatrienoic [12] acids were used. The methyl 15-cis-(2R)-2-hydroxydocosenoate (0.7 mg), methyl 16-cis-(2R)-2acetyloxytricosenoate (1.2 mg) and 15-cis-tetracosenoic acid (6.0 mg in two drops of CHCl 3 ) were converted into corresponding trans-isomers using a modified procedure [13] of isomerization with nitrogen oxides (1.5 h at 25−30 ºC: NaNO 2 , 5 mg, and water, 20 mkl, and 50 % aqueous solution of HNO 3 , 50 mkl, in a capped vial).…”

Structural Analysis of Oxidized Cerebrosides from the Extract of Deep-Sea Sponge Aulosaccus sp.: Occurrence of Amide-Linked Allylically Oxygenated Fatty Acids

“…The 1 Н-NМR spectrum of these compounds also showed signals of the terminal methyl groups of dominant normal-chain (δ Н 0.88, t, J = 6.9 Hz) and minor cyclopropane-containing (δ Н 0.89, t, J = 6.9 Hz) constituents. Under our conditions of hydrogenation, ring opening was not the dominant process for the minor constituent, so the signals of cis-cyclopropane protons at δ Н −0.33 (dt, J = 4.2, 5.5 Hz), 0.56 (ddd, J = 4.2, 8.3, 8.3 Hz), and 0.645 (m) [32] were observed. The hydrolysis of derivatized oxidized cerebrosides from part 2 with subsequent acetylation of products gave three sphingoid base derivatives.…”

“…In particular, some bacterial branched-chain, cyclopropane-containing FAs, and their monoenoic precursors were present in significant amounts in Aulosaccus sp. [32], and an overwhelming number of the sterols (stanols, ∆ 5 -, ∆ 7 -, and ∆ 8 (14) -sterols) of this sponge were oxidized to the corresponding 3-ketosteroids [37]. The occurrence of these FAs and steroids in Aulosaccus sp.…”

Steroids from a Far-Eastern Glass Sponge Aulosaccus sp.

“…Our earlier study 46 indicated that Aulosaccus sp. contained significant amounts of fatty acids of microbial origin.…”

“…suggested that this sponge was associated with mycobacteria or related microbes. 46 Notably, the bacteria of this group (phylum Actinobacteria) are not only known as sponge specific microorganisms, 47 but these microbes are also potent steroid degraders, particularly active in the catabolism of sterols. 48 The proposed oxidation of sterols in Aulosaccus sp.…”