zur Suche springenzur Navigation springenzum Inhalt springen

Publikationen - Natur- und Wirkstoffchemie

Sortieren nach: Erscheinungsjahr Typ der Publikation

Zeige Ergebnisse 1 bis 10 von 51.

Publikation

Yurkov, A.; Krüger, D.; Begerow, D.; Arnold, N.; Tarkka, M. T.; Basidiomycetous Yeasts from Boletales Fruiting Bodies and Their Interactions with the Mycoparasite Sepedonium chrysospermum and the Host Fungus Paxillus Microb. Ecol. 63, 295-303, (2012) DOI: 10.1007/s00248-011-9923-7

Interactions between mushrooms, yeasts, and parasitic fungi are probably common in nature, but are rarely described. Bolete fruiting bodies are associated with a broad spectrum of microorganisms including yeasts, and they are commonly infected with filamentous mycoparasites of the genus Sepedonium (teleomorph Hypomyces). We report the isolation of 17 yeast strains from Paxillus and Xerocomus, 16 of which were obtained from the surface tissue, the primary site of Sepedonium infection. Phylogenetic analyses with the D1/D2 region of the 28S ribosomal gene and the internal transcribed spacers placed the yeasts as Rhodotorula, Rhodosporidium, and Mastigobasidium from the Pucciniomycotina, Cryptococcus, Cystofilobasidium, Holtermanniella, and Trichosporon from the Agaricomycotina, and Kluyveromyces from the Saccharomycotina including the first isolation of Rhodotorula graminis from Europe. To investigate the influence of the yeast strains on the mycoparasite and the host fungus, in vitro assays were conducted with Sepedonium chrysospermum and Paxillus involutus. Both S. chrysospermum growth inhibitory and stimulating yeast strains were detected among the isolates. The number of S. chrysospermum inhibitory yeast strains increased and the number of S. chrysospermum stimulatory yeast strains decreased in the presence of P. involutus in co-cultures. Low nutrient levels in the culture medium also led to an increased number of S. chrysospermum inhibitory yeast strains and ten yeasts inhibited the mycoparasite in spatial separation by a crosswall. Six yeast strains inhibited P. involutus in dual culture, and the inhibitory P. involutus yeast interactions increased to nine in the presence of S. chrysospermum. Our results suggest that the bolete-associated yeasts influence the growth of the mycoparasitic fungus, which may affect the health of the fruiting bodies.
Publikation

Yeboah, S. O.; Mitei, Y. C.; Ngila, J. C.; Wessjohann, L.; Schmidt, J.; Compositional and structural studies of the oils from two edible seeds: Tiger nut, Cyperus esculentum, and asiato, Pachira insignis, from Ghana Food Res. Int. 47, 259-266, (2012) DOI: 10.1016/j.foodres.2011.06.036

A comprehensive lipid profiling has been carried out on the seed oils of tiger nut, Cyperus esculentum, and asiato, Pachira insignis, from Ghana in order to evaluate their potential uses for the region. Composition of FAs and phytosterols were determined using GC–MS, while tocol composition was determined with HPLC. TAG composition and regiochemistry were determined using ES-FTICR-MS and 13C NMR, respectively. The major FA components in asiato seed oil were palmitic acid (56.58%) and sterculic and dihydrosterculic acids (20.06% combined). The major FA components in tiger nut oil were oleic (65.55%), palmitic (16. 32%), and linoleic (12.13%) acids. Asiato seed oil had 18 major TAG classes, dominated by, C51:1 (38.45%) and C50:1 (13.941%). Tiger nut oil had 7 major TAG classes, with C54:3 (29.00%) and C52:2 (27.82%) dominating. The sn-1/3 and sn-2 positions in the TAGS for asiato oil were predominantly occupied by saturated acyl chains (87.25%) and cyclic acyl chains (71.44%), respectively. Oleoyl chain primarily occupied both sn-1/3 (52.68%) and sn-2 (77.62%) positions in the tiger nut oil. Total tocol content in asiato oil was 200.31 μg/g, with γ-tocopherol (182.99 μg/g) dominating. Tiger nut oil had a total tocol content of 120.10 μg/g, dominated by α-tocopherol (86.73) and β-tocopherol (33.37 μg/g).Tiger nut oil had total 4-desmethylsterol content of 986 μg/g, dominated by β-sitosterol (517.25 μg/g) and stigmasterol (225.25 μg/g), while asiato oil had total desmethylsterol content of 590.24 μg/g, dominated by β-sitosterol (518.91 μg/g). The presence of cyclopropenoid FAs in asiato oil makes it unsuitable for food uses. Tiger nut oil can replace imported olive oil in food products in the West African region.
Publikation

Wessjohann, L.; Vogt, T.; Kufka, J.; Klein, R.; Prenyl- und Methyltransferasen in Natur und Synthese BIOspektrum 18, 22-25, (2012) DOI: 10.1007/s12268-012-0137-4

Late stage enzymatic prenylation and methylation are means to diversify (natural) compounds and to specify their functions. In eukaryotes and microbes, these steps are performed by large enzyme families, the prenyl and methyl transferases, which modify various types of small molecules, like isoprenoids, phenolics or alkaloids, but also DNA and proteins. We investigate the theoretical basis of these processes and possible commercial applications in synthetic chemistry.
Publikation

Welsch, S. J.; Kalinski, C.; Umkehrer, M.; Ross, G.; Kolb, J.; Burdack, C.; Wessjohann, L. A.; Palladium and copper catalyzed cyclizations of hydrazine derived Ugi products: facile synthesis of substituted indazolones and hydroxytriazafluorendiones Tetrahedron Lett. 53, 2298-2301, (2012) DOI: 10.1016/j.tetlet.2012.02.095

Indazolones are medicinally relevant targets. Herein we disclose an improved synthesis to N′-(acetamido-2-yl)-substituted indazolones with four points of diversity introduced by Ugi-[M]-amination and -amidation. The ring closure can be achieved by either conventional palladium catalysis or with a ligandless copper protocol. When α-unbranched isocyanides were employed the sole cyclization products of the copper catalyzed reactions are the hitherto undescribed 2-hydroxy-3H-3,4a,9a-triaza-fluorene-4,9-diones.
Publikation

van Berkel, S. S.; Brauch, S.; Gabriel, L.; Henze, M.; Stark, S.; Vasilev, D.; Wessjohann, L. A.; Abbas, M.; Westermann, B.; “Spurlose” Tosylhydrazon-basierte Triazolsynthese: eine metallfreie Alternative zur ringspannungskatalysierten Azid-Alkin-Cycloaddition Angew. Chem. 124, 5437-5441, (2012) DOI: 10.1002/ange.201108850

Durch Reaktion primärer Amine mit funktionalisierten α,α‐Dichlortosylhydrazonen unter milden Bedingungen gelingt eine „spurlose“ Tosylhydrazon‐basierte Triazolsynthese, die ausschließlich zur Bildung 1,4‐substituierter Triazol‐„Klick‐Produkte“ unter vollständigem Konfigurationserhalt am Stereozentrum führt. Primäre Amine, die in vielen Naturstoffen vorkommen, können chemoselektiv ohne die Notwendigkeit einer umfassenden Schutzgruppenstrategie modifiziert werden.
Publikation

van Berkel, S. S.; Brauch, S.; Gabriel, L.; Henze, M.; Stark, S.; Vasilev, D.; Wessjohann, L. A.; Abbas, M.; Westermann, B.; Traceless Tosylhydrazone-Based Triazole Formation: A Metal-Free Alternative to Strain-Promoted Azide-Alkyne Cycloaddition Angew. Chem. Int. Ed. 51, 5343-5346, (2012) DOI: 10.1002/anie.201108850

Triple‐T trick! Traceless tosylhydrazone‐based triazole formation is readily achieved by reacting primary amines with functional α,α‐dichlorotosylhydrozones under ambient conditions. This fast and efficient alternative affords exclusively 1,4‐substituted triazole “click products” with complete retention of configuration. Primary amines, inherent to many natural products, can be modified in this way without protecting group manipulations.
Publikation

van Berkel, S. S.; Bögels, B. G. M.; Wijdeven, M. A.; Westermann, B.; Rutjes, F. P. J. T.; Recent Advances in Asymmetric Isocyanide-Based Multicomponent Reactions Eur. J. Org. Chem. 2012, 3543-3559, (2012) DOI: 10.1002/ejoc.201200030

This review discusses the use of various isocyanides (regular, chiral, and convertible) in asymmetric multicomponent reactions. In particular, stereoselective Ugi and Passerini reactions are highlighted, as well as their applications in modular sequential reactions and natural product synthesis.Isocyanide‐based multicomponent reactions (IMCRs) can be considered one of the breakthrough reaction classes of the last century. Moreover, asymmetric IMCRs have recently developed into powerful reactions for the versatile synthesis of highly complex molecules. The progress made in the development of stereoselective Passerini and Ugi reactions has led to the advancement of catalytic asymmetric IMCRs. This review gives an overview of recent advances in the field of asymmetric IMCRs with a focus on stereoselective α‐additions of isocyanides. In addition, the use of convertible isocyanides in stereoselective cascade IMCRs is covered and future opportunities and potential applications of (asymmetric) IMCRs are briefly discussed.
Publikation

Thomsen, H.; Reider, K.; Franke, K.; Wessjohann, L. A.; Keiser, J.; Dagne, E.; Arnold, N.; Characterization of Constituents and Anthelmintic Properties of Hagenia abyssinica Sci. Pharm. 80, 433-446, (2012) DOI: 10.3797/scipharm.1109-04

The dried female flowers of Hagenia abyssinica (Bruce) J. F. Gmel. (Rosaceae) are traditionally used as an anthelmintic remedy in Ethiopia and formerly were incorporated into the European Pharmacopoeia. One-, two- and tricyclic phloroglucinol derivatives (kosins) were suggested to be the active principles. However, polar constituents may also contribute to the activity. Therefore, we investigated for the first time the polar constituents. We isolated typical Rosaceae constituents such as quercetin 3-O-β-glucuronide, quercetin 3-O-β-glucoside and rutin. Polar kosin glycosides or derivatives could not be detected.The anthelmintic activity of fractions of different polarity were tested against the blood fluke Schistosoma mansoni, the liver flukes Clonorchis sinensis and Fasciola hepatica and the intestinal fluke Echinostoma caproni. The anthelmintic activity decreased with increasing polarity of the tested fractions. ESI-MS investigations indicated the predominant occurrence of kosins in the active fractions.Using the anthelmintic active extracts of Hagenia abyssinica we developed a simple, inexpensive bioassay against the non-parasitic nematode Caenorhabditis elegans, which can be used as an initial screening procedure for anthelmintic properties of crude extracts of plants or fungi. The anthelmintic activity of test extracts against the model organism was determined in a microtiter plate assay by enumeration of living and dead nematodes under a microscope.
Publikation

Thien, D. G.; Hoang Anh, N. T.; Porzel, A.; Franke, K.; Wessjohann, L.; Van Sung, T.; Triterpene acids and polyphenols from Eriobotrya poilanei Biochem. Syst. Ecol. 40, 198-200, (2012) DOI: 10.1016/j.bse.2011.11.001

The occurrence of flavolignans might be a valuable chemotaxonomic marker for the classification of Rosaceae species.
Publikation

Tarman, K.; Palm, G. J.; Porzel, A.; Merzweiler, K.; Arnold, N.; Wessjohann, L. A.; Unterseher, M.; Lindequist, U.; Helicascolide C, a new lactone from an Indonesian marine algicolous strain of Daldinia eschscholzii (Xylariaceae, Ascomycota) Phytochem. Lett. 5, 83-86, (2012) DOI: 10.1016/j.phytol.2011.10.006

From an endophytic Daldinia eschscholzii strain isolated from the agar-producing red alga Gracilaria sp. SGR-1, collected from the coast of South Sulawesi, Indonesia, a new lactone helicascolide C (1) was obtained as colourless crystals from the ethyl acetate extract together with the related structurally known compound helicascolide A (2). The structure of the new compound 1 reveals a carbonyl group replacing an alcohol group of compound 2. The structure of 1 was elucidated by X-ray diffraction and spectral analyses. Compound 1 showed fungistatic activity against the phytopathogenic fungus Cladosporium cucumerinum.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
IPB Mainnav Search