New Sphingolipids with a Previously Unreported 9‐Methyl‐C₂₀‐sphingosine Moiety from a Marine Algous Endophytic Fungus Aspergillus niger EN‐13

Abstract

Asperamides A (1) and B (2), a sphingolipid and their corresponding glycosphingolipid possessing a hitherto unreported 9-methyl-C20-sphingosine moiety, were characterized from the culture extract of Aspergillus niger EN-13, an endophytic fungus isolated from marine brown alga Colpomenia sinuosa. The structures were elucidated by spectroscopic and chemical methods as (2S,2'R,3R,3'E,4E,8E)-N-(2'-hydroxy-3'-hexadecenoyl)-9-methyl-4,8-icosadien-1,3-diol (1) and 1-O-beta-D-glucopyranosyl-(2S,2'R,3R,3'E,4E,8E)-N-(2'-hydroxy-3'-hexadecenoyl)-9-methyl-4,8-icosadien-1,3-diol (2). In the antifungal assay, asperamide A (1) displayed moderate activity against Candida albicans.

Unusual Outer Membrane Lipid Composition of the Gram-negative, Lipopolysaccharide-lacking Myxobacterium Sorangium cellulosum So ce56

“…NMR analysis confirmed this result and showed a ␤-linkage (J 1,2 7.9 Hz) to the sphingosine moiety. This result was also in accordance with reported structures (28,31).…”

“…This is in agreement with the fact that only D-erythro-sphingosine is known to occur in nature (30). Thus, we proposed for the determined sphingosine variants the abso- lute stereochemistry D-erythro (2S,3R), which allowed the two variants of C 21 -sphingosine to be described more precisely as (2S,3R,4E,8E,10E)-9-methyl-4,8,10-icosatrien-1,3-diol (21:3) and (2S,3R,4E,8E)-9-methyl-4,8-icosadien-1,3-diol (21: 2), corresponding to earlier reports (28,31,32).…”

“…Possible minimal changes in NMR shifts for other protons could not be excluded, but were not evaluable (only for 3-H a separated signal was visible). Furthermore, NMR analysis showed that all sphingolipid types occurred in two different variants of the C 21 (28). In all cases 21:3 was the predominant variant (SL: 75%, GSL: 90%, AEPnSLϩPEASL: 83%; ratios were determined by integrating the respective methyl groups at C-9).…”

Benzaldehyde Derivatives from Eurotium rubrum, an Endophytic Fungus Derived from the Mangrove Plant Hibiscus tiliaceus

“…over silica gel eluted with different solvents of increasing polarity to yield 14 fractions (Frs. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] on the basis of TLC analysis. Fr.…”

“…Many secondary metabolites with novel structures and biological activities have been characterized from mangrove-derived endophytic fungi. [5][6][7][8] In the course of our ongoing project directed toward the discovery of new natural products from endophytic fungi that were isolated from marine organisms from the Chinese sea coasts, [9][10][11][12][13][14] we have investigated the chemical constituents of an endophytic fungal strain Eurotium rubrum that was isolated from the inner tissue of stems of the mangrove plant Hibiscus tiliaceus collected from Hainan island. This paper describes the isolation, structure elucidation, and cytotoxicity of four new (1-4) and seven known (5-11) benzaldehyde derivatives.…”