Hans Achenbach

The pigments of Flexibacter elegans: Novel and chemosystematically useful compounds

Abstract1.Flexibacter elegans Fx e1 contains 3 pigments; their quantitative proportion is 2.5 : 2.5 : 95%. The absolute pigment content is 0.6–0.8 μg per mg dry cells.2.Contrary to statements in the literature, these pigments are not carotenoids. This can be deduced from their electronic spectra which lack fine structure and are pH-dependent; from their resistance to photooxidation; from their failure to incorporate 14C-mevalonate; and from their mass spectra which do not show the M-92 and M-106 fragments typical for carotenoids.3.The main pigment is characterized in detail; it has been named flexirubin.4.The new pigments are widely distributed among members of the Cytophaga-Flexibacter group and seem to be valuable chemosystematic markers.5.Specific pigment content of the bacteria does neither change along the growth curve, nor under illumination. Low pH or high phosphate concentrations depress specific pigment content.6.The taxonomical position of experimental strain Fx e1 is discussed: The organism shows a cyclic change in cell shape. In young cultures there are long and very agile thread cells which fragment later in culture development, until finally only very short rods remain. A redefinition of the genus Flexibacter based on this shape change is proposed.

Iridoid and other constituents of Canthium subcordatum

Abstract The main constituent of the stem bark of Canthium subcordatum was found to be shanzhiside methyl ester, an iridoid recently described for two Mussaenda species; it is accompanied by the new iridoid shanzhisin methyl ester gentiobioside. No alkaloids were detected.

Flexirubin-type pigments in Flavobacterium

In an organism (strain C 1/2 from Dr. P. R. Hayes, Leeds) regarded as a typical representative of the genus Flavobacterium, flexirubin-type pigments have been identified. The Flavobacterium pigments contain structural elements of both, the pigments of the genus Flexibacter and the pigments of the genus Cytophaga. As flexirubin-type pigments seem to have a rather restricted distribution among bacteria, and have formerly proved to be useful chemosystematic markers for the flexibacteria, this new observation may indicate that there is a relatively close phylogenetic relationship between this type of flavobacteria and the Cytophaga-Flexibacter group.

Investigations of the pigments fromCytophaga johnsonae Cy j1

Besides carotenoids a complex of flexirubin-type pigments was isolated from the gliding bacterium Cytophaga johnsonae Cy jl and separated into 6 components, which partly containe chlorine. In spite of the fact that these components still consist of pigment mixtures, the gross structures of 18 new flexirubin-type pigments could be deduced by spectroscopic and chemical investigations. The results open insights into biosynthesis and structural variety of the flexirubins, the novel non-isoprenoid pigments recently found in Flexibacter elegans.Besides carotenoids a complex of flexirubin-type pigments was isolated from the gliding bacteriumCytophaga johnsonae Cy j1 and separated into 6 components, which partly containe chlorine. In spite of the fact that these components still consist of pigment mixtures, the gross structures of 18 new flexirubin-type pigments could be deduced by spectroscopic and chemical investigations. The results open insights into biosynthesis and structural variety of the flexirubins, the novel non-isoprenoid pigments recently found inFlexibacter elegans.

5,7-Dihydroxy-3,6,8-trimethoxyflavone from the flowers of Gnaphalium elegans☆

Abstract 5,7-Dihydroxy-3,6,8-trimethoxyflavone was isolated from the flowers of Gnaphalium elegans . The structure elucidation is based mainly on proton resonance studies using Eu(fod) 3 shift reagent.

Carotenoid pigments of Stigmatella aurantiaca (Myxobacterales)

SummaryThe two main carotenoids of Stigmatella aurantiaca were identified as 1′,2′-dihydro-1′-hydroxy-3,4-dehydro-torulene glucoside (myxobactin) and 1′,2′-dihydro-1′-hydroxy-4-keto-torulene glucoside (myxobacton). Both pigments occur as monoesters of various fatty acids. The structural formulas were established by chemical and chromatographical analysis and by visible, infrared, and mass spectroscopy.

Metabolic products of microorganisms

In the course of a screening for new metabolites from fungi we isolated a substance with antimicrobial activity from cultures of Aspergillus duricaulis (CBS 481.65) (Tü 679). It was antagonized by putrescine, spermidine, spermine, arginine, citrulline, lysine, ornithine, in higher concentration by asparagine and glutamine too. The effect of ethylenediaminetetraacetate on the susceptibility of Streptomyces viridochromogenes (Tü 57) and Bacillus subtilis ATCC 6051 to this antibiotic has been studied.The substance was characterized and identified as cyclopaldic acid.

Carotenoid pigments of Sorangium compositum (Myxobacterales) including two new carotenoid glucoside esters and two new carotenoid rhamnosides

SummaryThe carotenoid pigments of the myxobacterium Sorangium compositum were analyzed by chromatographical and chemical techniques and by visible, infra red, and mass spectroscopy. Besides γ-carotene, neurosporene, torulene, lycopene, and 1′,2′-dihydro-1′-hydroxy-γ-carotene, four new carotenoid glycosides were found. These pigments were identified as 1′,2′-dihydro-1′-hydroxy-torulene glucoside ester (I), 1′,2′-dihydro-3,1′-dihydroxy-torulene glucoside ester (III), 1′,2′-dihydro-1′-hydroxy-torulene rhamnoside (II), and 1′,2′-dihydro-3,1′-dihydroxytorulene rhamnoside (IV).

3,6-bis(γ,γ-dimethylallyl)-indole from uvaria elliotiana

Abstract The new title compound 1 has been isolated from the stem bark of Uvaria elliotiana Engl. & Diels (Annonaceae).

Untersuchungen zur biogenese des flexirubins—herkunft des benzolringes a und der aromatischen C-methylgruppen

Abstract In radioactive flexirubins formed in culture from different radioactive precursors, the labelling was located by chemical degradation. The results show unambiguously that only the methyl group of ring A originates from methionine. The benzene ring A is derived from tyrosine, which is incorporated as a C 6 -C 3 unit. Acetate acts as the main precursor of the polyene and participates in the biosynthesis of ring B.