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B Vogler

Publications and source records attributed to B Vogler.

At least 19 recordsLinked to original sources
PubMed2005

HPLC-coupled spectroscopic techniques (UV, MS, NMR) for the structure elucidation of phthalides in Ligusticum chuanxiong.

Ligusticum chuanxiong Hort., a plant that is frequently used in traditional Chinese medicine, has been studied using HPLC-coupled spectroscopic techniques such as HPLC-UV, HPLC-MS as well as HPLC-NMR. With the aid of these modern spectroscopic techniques, the main constituents, namely senkyunolide A, butylphthalide, neocnidilide and Z-ligustilide, have been characterized and identified. Phthalide dimers, present in smaller amounts, have been identified by HPLC-UV and HPLC-MS analysis and compared with reference compounds. Stereochemical features of some phthalide monomers have been determined by detailed spectroscopic studies for the first time.

Chromatography, High Pressure Liquid↗
PubMed2003

Scaphopetalone and scaphopetalumate, a lignan and a triterpene ester from Scaphopetalum thonneri.

From the methanol extract of the stem bark of Scaphopetalum thonneri, two new compounds, including one lignan, named scaphopetalone, one new ester of ferulic acid, named scaphopetalumate were isolated together with three known compounds including: two coumarins (scopoletin and scopolin), and one pentacyclic triterpene (oleanolic acid). The structure of the new compounds were elucidated by means of spectroscopic analyses.

Cameroon↗
PubMed2001

Sesquiterpene lactones and a myoinositol from glandular trichomes of Viguiera quinqueremis (Heliantheae; Asteraceae).

The extract of the floral parts of Viguiera quinqueremis afforded, in addition to known compounds, six new sesquiterpene lactones as well as a new myoinositol derivative. All compounds were detected in glandular trichomes which were collected micromechanically from the anther appendages and were analyzed by HPLC. Structure identification was performed by 1H NMR measurements including LC NMR and LC MS experiments.

Asteraceae↗
PubMed2001

Isolation and identification of N-mercapto-4-formylcarbostyril, an antibiotic produced by Pseudomonas fluorescens.

Pseudomonas fluorescens strain G308 isolated from barley leaves produces a novel antibiotic substance that was purified by preparative TLC and HPLC and identified as N-mercapto-4-formylcarbostyril (Cbs) by LC/DAD, IR, LC-ES(+)/MS, LC-ES(-)/MS, GC-EI/MS, LC-HRES(+)/MS, mass isotope ratios analysis, 1H NMR and 13C NMR analysis. The purified new antibiotic compound is effective against many phytopathogenic fungi in vitro. The compound inhibited at 25 ppm spore germination and germ tube growth of the following fungi; Fusarium oxysporum f. sp. lycopersici, Fusarium culmorum, Cladosporium cucumerinum and Colletotrichum lagenarium. At concentrations up to 125 ppm, the compound did not interfere with release of zoospores from sporangia and germination of encysted zoospores of Phytophthora infestans.

Antifungal Agents↗
PubMed2001

Isoterchebulin and 4,6-O-isoterchebuloyl-D-glucose, novel hydrolyzable tannins from Terminalia macroptera.

Two new hydrolyzable tannins, isoterchebulin (1) and 4,6-O-isoterchebuloyl-D-glucose (2), together with six known tannins, 3-8, were isolated from the bark of Terminalia macroptera. Their structures were elucidated by extensive 1D and 2D NMR studies, MS, and chemical transformations. Biological activities of all compounds were evaluated against the snail Biomphalaria glabrata, the bacteria Bacillus subtilis and Pseudomonas fluorescens, the nematode Caenorhabditis elegans, and four cancer cell lines (Hep G2, MCF-7/S, MDA-MB-231, and 5637 cells). All compounds except 3 showed antimicrobial activities against B. subtilis (MIC 8-64 microg/mL), whereas only 1 was active against C. elegans (100 microg/mL) and B. glabrata(LC(100) = 60 microg/mL). 3 and 8 were toxic against 5637 cells with LC(50) = 84.66 and 41.40 microM, respectively.

Africa↗
PubMed2001

Isolation and frontier molecular orbital investigation of bioactive quinone-methide triterpenoids from the bark of Salacia petenensis.

The crude dichloromethane bark extract of Salacia petenensis (Hippocrateaceae) from Monteverde, Costa Rica, shows antibacterial and cytotoxic activity. Bioactivity-directed separation led to the isolation of tingenone and netzahualcoyonol as the biologically active materials. Also isolated from the extract were 3-methoxyfriedel-2-en-1-one (a new natural product) and 29-hydroxyfriedelan-3-one. The structures of these compounds were elucidated on the basis of NMR spectral analysis. Molecular orbital calculations have been carried out using the semi-empirical PM3 and Hartee-Fock 3-21G ab initio techniques on the quinone-methide nortriterpenoids tingenone and netzahualcoyonol, as well as on the nucleotide bases adenine, guanine, cytosine, and thymine. The molecular orbital calculations suggest that a possible mode of cytotoxic action of quinone-methide triterpenoids involves quasi-intercalative interaction of the compounds with DNA followed by nucleophilic addition of the DNA base to carbon-6 of the triterpenoid.

Indolequinones↗
PubMed2001

Isolation from Cussonia barteri of 1'-O-chlorogenoylchlorogenic acid and 1'-O-chlorogenoylneochlorogenic acid, a new type of quinic acid esters.

1'-O-Chlorogenoylchlorogenic acid and 1'-O-chlorogenoylneochlorogenic acid, a new type of quinic acid esters, have been isolated, in addition to six known quinic acid esters, rutin, and a mixture of saponins, from the methanol extract of Cussonia barteri Seemann (Araliaceae) leaves collected in Cameroon. Structure determination was achieved by NMR, mass, IR, and UV spectroscopy. All compounds were tested for inhibitory activity on 5-lipoxygenase and cyclooxygenase-1, for antimicrobial activity against Bacillus subtilis, Pseudomonas fluorescens, and Cladosporium cucumerinum, and for haemolytic activity.

Anti-Infective Agents↗
PubMed2001

Vanillic acid 4-O-beta-D-(6'-O-galloyl) glucopyranoside and other constituents from the bark of Terminalia macroptera Guill.et Perr.

A new phenolic glucoside gallate, vanillic acid 4-O-beta-D-(6'-O-galloyl) glucopyranoside (1) was isolated from the bark of Terminalia macroptera Guill.et Perr., together with 3,3',4'-tri-O-methylellagic acid (2) and two triterpene glucopyranosyl esters, 24-deoxysericoside (3) and chebuloside II (4). Compounds 2-4, not described previously for this plant, showed antimicrobial activities against Bacillus subtilis, while 3 and 4 possessed haemolytic properties. In both assays 1 was found to be inactive.

Bacillus subtilis↗
PubMed2000

Sesquiterpene lactones in Viguiera eriophora and Viguiera puruana (Heliantheae; Asteraceae).

Extracts of the aerial parts of Viguiera eriophora ssp. eriophora and Viguiera puruana afforded, in addition to known compounds, six new heliangolides and a germacrolide, whose structures were determined by spectral analysis. HPLC analysis and LC NMR experiments revealed the natural occurrence of the compounds in glandular trichomes. The taxonomic relevance of the results is briefly discussed.

Asteraceae↗
PubMed2000

Novel extracellular diterpenoids with biological activity from the cyanobacterium Nostoc commune.

Five novel extracellular metabolites with an unprecedented diterpenoid skeleton, 5-[(5-carboxy-2-hydroxy)benzyl]-11-hydroxymethyl-2,5,6,8a, 11-pentamethyldodecahydrocyclopenta naphthalene (1), 5-[(5-carboxy-2-hydroxy)benzyl]-11-formyl-2,5,6,8a, 11-pentamethyl-dodecahydrocyclopenta naphthalene (2), 5-[(5-carboxy-2-hydroxy)benzyl]-11-carboxy-2,5,6,8a, 11-pentamethyl-dodecahydrocyclopenta naphthalene (3), 5-[(5-carboxy-2-hydroxy)benzyl]-11-dihydroxymethyl-2,5,6,8a, 11-pentamethyldodecahydrocyclopenta naphthalene (4), and 5-[(5-carboxy-2-hydroxy)benzyl]-11-acetyl-2,5,6, 8a-tetramethyldodecahydrocyclopenta naphthalene (5), have been isolated from the culture medium of the terrestrial cyanobacterium Nostoc commune by means of bioguided isolation. The molecules were designated as comnostins A-E. The structures were determined by spectroscopic methods, mainly NMR and mass spectrometry. The relative stereochemistry of comnostin A was confirmed by single-crystal X-ray structure analysis. All comnostins showed antibacterial activities. Additionally, cytotoxic and molluscicidal activities were found for comnostin B.

Cyanobacteria↗
PubMed1999

Application of high-performance liquid chromatography coupled to nuclear magnetic resonance spectrometry, mass spectrometry and bioassay for the determination of active saponins from Bacopa monniera Wettst.

Reversed-phase high-performance liquid chromatographic separation coupled to (structurally informative) spectroscopic methods like NMR and MS and an efficient bioassay have been used to determine the active compounds from a crude fraction of Bacopa monniera. The fraction containing a mixture of saponins with closely related structures was found to show a significant anthelmintic activity against Caenorhabditis elegans (used as a model test organism for determining anthelmintic activity). The activity was correlated to two dammarane type triterpenoidal saponins containing at least three sugar units. The optimization of separation for 1 mg of the crude sample on column and the sensitivity of on-flow one- and two-dimensional NMR experiments to the high-molecular-mass compounds (M(r) 890-930) has been demonstrated.

Animals↗
PubMed1998

Biosynthesis of vitamin B12 in anaerobic bacteria--experiments with Eubacterium limosum on the transformation of 5-hydroxy-6-methyl-benzimidazole, its nucleoside, its cobamide, and of 5-hydroxybenzimidazolylcobamide in vitamin B12.

In anaerobic bacteria 5-hydroxybenzimidazole and 5-hydroxy-6-methylbenzimidazole are precursors of the 5,6-dimethylbenzimidazole moiety of vitamin B12. In order to elucidate the pathway from these bases to vitamin B12, experiments on the transformation of 5-hydroxy-6-methylbenzimidazole, of 5-hydroxy-6-methylbenzimidazole-alpha-D-ribofuranoside, of 5-hydroxybenzimidazolylcobamide and of 5-hydroxy-6-methylbenzimidazolylcobamide into vitamin B12 were carried out. The vitamin B12 synthesized by the anaerobe Eubacterium limosum in the presence of 5-hydroxy-6-methylbenzimidazole and L-[methyl-13C]methionine was subjected to NMR spectroscopy. It revealed that the methyl group at C5 of the 5,6-dimethylbenzimidazole moiety was 13C labeled, whereas the methyl group at C6 was unlabeled. This shows that the transformation of 5-hydroxy-6-methylbenzimidazole into the base moiety of vitamin B12 occurs regiospecifically. 5-Hydroxy-6-methylbenzimidazole-alpha-D-ribofuranoside as well as 5-hydroxybenzimidazolylcobamide and 5-hydroxy-6-methylbenzimidazolylcobamide were also transformed into vitamin B12 by E. limosum. When 5-hydroxy-6-methylbenzimidazolylcobamide 13C labeled at C2 of the base part and 14C labeled in the ribose was used for this experiment, the vitamin B12 obtained from this cobamide was 13C and 14C labeled in the same positions. This demonstrates that the alpha-glycosidic bond of the precursor cobamide is not split during the formation of vitamin B12. It can be deduced from these results that the precursor bases are transformed regiospecifically into their alpha-nucleotides, and partially into their cobamides. The alpha-nucleotides are then transformed into alpha-ribazole-5'-phosphate and, subsequently, into vitamin B12. Most likely the cobamides are degraded to the alpha-nucleotides before being used for the biosynthesis of vitamin B12. A pathway for the latter process is suggested.

Benzimidazoles↗
PubMed1998

Combination of LC-MS and LC-NMR as a Tool for the Structure Determination of Natural Products

Application of both LC-MS and LC-NMR to a partially purified extract of Vernonia fastigiataled to the direct identification of antibacterial sesquiterpene lactones 1-9 without isolation of individual compounds. The rapid structural analysis of both major and minor components of this class of compounds demonstrated the power of structure-guided screening as a complementary method to assay-guided screening.

Journal Article↗
PubMed1995

7-Azabenzimidazolylcobamide and 5,6-dimethyl-7-azabenzimidazolylcobamide, new vitamin B12-analogs synthesized from 4(5)-aminoimidazole by Eubacterium limosum.

In anaerobic bacteria, glycine, formate, and the amide-N of glutamine are building blocks for the biosynthesis of the imidazole moiety of the vitamin B12-base 5,6-dimethylbenzimidazole. These building blocks are also used for the biosynthesis of the imidazole moiety of purine bases. Therefore we tested 4(5)-aminoimidazole, the base moiety of the purine nucleotide precursor 5-aminoimidazole ribonucleotide, for its putative function as precursor of 5,6-dimethylbenzimidazole. The anaerobic vitamin B12-producer Eubacterium limosum, grown in the presence of [2-13C]4(5)-aminoimidazole, synthesized nonlabeled vitamin B12, but also [2-13C]7-azabenzimidazolylcobamide and [2-13C]5,6-dimethyl-7-azabenzimidazolylcobamide. [2-13C]limidazole was used by E. limosum to form [2-13C]imidazolylcobamide. Simultaneously nonlabeled vitamin B12 was synthesized. This shows that 4(5)-aminoimidazole and imidazole are not intermediates in the biosynthesis of 5,6-dimethylbenzimidazole. However, 4(5)-aminoimidazole has obviously a structure similar to the structure of an as yet unknown precursor of the vitamin B12-base, and is therefore transformed into the aza analogs. In order to prepare a reference compound 4(5)-azabenzimidazole was added to a culture of Propionibacterium shermanii and to a culture of E. limosum, P. shermanil transformed this base mainly to 4-azabenzimidazolylcobamide, as determined by 1H NMR-spectroscopy (NOE experiment). In contrast E. limosum produced mainly 7-azabenzimidazolylcobamide. The reason for this difference is discussed.

Anaerobiosis↗
PubMed1994

Metabolism of 4-chlorophenol by Azotobacter sp. GP1: structure of the meta cleavage product of 4-chlorocatechol.

A mutant strain of Azotobacter sp. GP1 converted 4-chlorophenol to 4-chlorocatechol under cometabolic conditions. Under the same conditions the wild-type strain accumulated a yellow compound, which by chemical and spectroscopic methods was identified as 5-chloro-2-hydroxy-6-oxohexadienoic acid (5-chloro-2-hydroxy-muconic semialdehyde). The structure of this compound indicates a meta-proximal cleavage of 4-chlorocatechol.

Azotobacter↗