The structure of the O-specific side chain of the lipopolysaccharide from the Gram-negative psychrophilic bacterium Moritella viscosa strain M2-226, responsible for the winter ulcer in Atlantic salmon, has been determined. Monosaccharide analysis and (1)H and (13)C NMR spectroscopy were employed to elucidate the structure. It was concluded that the polysaccharide is composed of a trisaccharide repeating unit with the following structure: →3)-β-D-GlcpNAc-(1→4)-[α-D-GlcpA-(1→3)]-α-L-Fucp-(1→ .

Immunochemical analysis of the Yokenella regensburgei lipopolysaccharides (LPS) indicated the presence of the core oligosaccharide-related immunotypes among the investigated strains. The structure of the core oligosaccharide segment of the Y. regensburgei LPS has been investigated using chemical methods, mass spectrometry, and (1)H, (13)C NMR spectroscopy. It was concluded that the core oligosaccharides of the strains PCM 2476 and PCM 2477 are composed of an undecasaccharide. The combined data revealed two immunotypes of the core oligosaccharide recognized by antibodies against the whole bacterial cells. The structural differences between the core oligosaccharides are limited to the outermost terminal hexopyranose residue. In the core oligosaccharide of the strain PCM 2476, it was identified as alpha-d-Glcp and in that of the strain PCM 2477 as alpha-d-Galp. This subtle difference between the glycoforms of the LPS core appeared to be essential for formation of the epitopes recognized by the specific antibodies directed against the Y. regensburgei whole bacterial cells. The oligosaccharides are not substituted by phosphate groups. Instead, the carboxyl groups of Kdo and galacturonic acid residues present in the core provide the negative charges. The undecasaccharides represent a novel core type of bacterial LPS, which is characteristic for Y. regensburgei.

Many sessile suspension-feeding marine organisms rely on chemical defense to keep their surfaces free from fouling organisms. The brominated cyclopeptides barettin (cyclo[(6-bromo-8-entryptophan)arginine]) ( 1) and 8,9-dihydrobarettin (cyclo[(6-bromotryptophan)arginine]) ( 2) from the cold-water sponge Geodia barretti have previously displayed settlement inhibition of barnacle larvae in a dose-dependent manner. In this paper, we describe a novel dibrominated cyclopeptide, bromobenzisoxazolone barettin (cyclo[(6-bromo-8-(6-bromobenzioxazol-3(1 H)-one)-8-hydroxy)tryptophan)]arginine) ( 3), which we have isolated from G. barretti and which displays settlement inhibition of barnacle larvae ( Balanus improvisus) with an EC 50 value of 15 nM. The chemical structure was determined using MS and 2D-NMR.

The structure of an acidic polysaccharide isolated from Abtorna augusta root bark was determined by sugar and methylation analyses and high resolution H-1- and C-13-NMR spectroscopy. The main chain of the polysaccharide was composed of 1,2-linked alpha-L-rhamnopyranose and 1,4- or 1,3-lifiked alpha-D-galacturonic acid residues. The terminal beta-D-glucuronic acid residue was attached to the 3- and/or 4-position of the alpha-D-galacturonic acid residue.

The red pigments exudated from Drechslera teres, D. graminea, D. tritici-repentis, D. phlei, D. dictyoides, D. avenae and Bipolaris sorokiniana , were extracted and isolated by means of thin-layer chromatography and/or high-performance liquid chromatography. Chemical characterization was made by spot-tests, uv-vis spectrophotometry and 1 H-nuclear magnetic resonance spectroscopy. The red pigment produced by the five first-mentioned Drechslera species was identified as the anthraquinone catenarin while that form D. avenae and B. sorokinana consisted of two other anthraquinones — cynodontin and helminthosporin. Catenarin was totally inhibitory against the Gram-positive bacterium Bacillus subtilis but not the Gram-negative bacterium Erwinia carotovora . However, catenarin could also partly inhibit the mycelium of D. teres itself.

An extract of Empetrum hermaphroditum Hagerup leaves was examined for germination inhibitors using an assay based on germination of Populus tremula L. seeds. The substances were extracted in water and purified by solvent partitioning. The acidic ethyl acetate fraction, containing the major part of the inhibitory activity was purified by reversed-phase high-performance liquid chromatography. Two zones of inhibitory activity were detected, combined and further purified by normal-phase HPLC. One major zone of inhibitory activity was thereafter detected and the substance in this fraction was crystallized and identified by nuclear magnetic resonance and gas chromatography-mass spectrometry as 5-methoxy-3,3'-dihydroxy-dihydrostilbene or batatasin III. Ca. 100 mg of the substance was then, by sequential HPLC, isolated in crystalline form from E. hermaphroditum leaves. The inhibitory activity of the pure substance was compared with a crude water extract of E. hermaphroditum leaves. It was concluded that the pure substance exhibited ca. 28 % of the inhibitory activity of the crude extract. The difference in inhibitory activity might be explained by the presence of a glucosidic conjugate of 5-methoxy-3,3'-dihydroxy-dihydrostilbene in the crude extract.

AbstractDie Titelverbindung (I) wird über die D‐xylo‐Hexopyranosid‐ulose (II) (nicht isoliert) in das O‐Methyl‐oxim (III) (Ausb.‐Angabe in g) übergeführt.

Die Titelverbindung (III) wird aus Ameisensäure (I) über das Triacetat (II) dargestellt.

D-gluco-Hexodialdose in Aqueous Solution : Determination of the Main Forms by NMR spectroscopy