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Publikationen - Natur- und Wirkstoffchemie

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Publikation

Arnold, N.; Palfner, G.; Kuhnt, C.; Schmidt, J.; Chemistry of the earthy odour of basidiomata of Cortinarius hinnuleus (Basidiomycota, Agaricales) Österr. Z. Pilzk. 25, 5-10, (2016)

Cortinarius hinnuleus (Earthy Webcap), a common mycorrhizal mushroom in Central Europe, is characterized by a mouldy earthy odour. The relevant volatile compounds were detected by gas chromatography-mass spectrometry using headspace-solid phase microextraction technology and identified as geosmin, ß-caryophyllene and ß-barbatene together with the C8-volatiles 1-octen-3-ol, 1-octen-3-one, octan-3-ol, octan-3-one, and 2-octen-1-ol.
Publikation

Al-Fatimi, M.; Ali, N. A. A.; Kilian, N.; Franke, K.; Arnold, N.; Kuhnt, C.; Schmidt, J.; Lindequist, U.; Ethnobotany, chemical constituents and biological activities of the flowers of Hydnora abyssinica A.Br. (Hydnoraceae) Pharmazie 71, 222-226, (2016) DOI: 10.1691/ph.2016.5808

Hydnora abyssinica A.Br. (Hydnoraceae), a holoparasitic herb, is for the first time recorded for Abyan governorate of South Yemen. Flowers of this species were studied for their ethnobotanical, biological and chemical properties for the first time. In South Yemen, they are traditionally used as wild food and to cure stomach diseases, gastric ulcer and cancer. Phytochemical analysis of the extracts showed the presence of terpenes, tannins, phenols, and flavonoids. The volatile components of the air-dried powdered flowers were identified using a static headspace GC/MS analysis as acetic acid, ethyl acetate, sabinene, α-terpinene, (+)-D-limonene and γ-terpinene. These volatile compounds that characterize the odor and taste of the flowers were detected for the first time in a species of the family Hydnoraceae. The flowers were extracted by n-hexane, dichlormethane, ethyl acetate, ethanol, methanol and water. With exception of the water extract all extracts demonstrated activities against Gram-positive bacteria as well as remarkable radical scavenging activities in DPPH assay. Ethyl acetate, methanol and water extracts exhibited good antifungal activities. The cytotoxic activity of the extracts against FL cells, measured in neutral red assay, was only weak (IC50 > 500 μg /mL). The results justify the traditional use of the flowers of Hydnora abyssinica in South Yemen.
Publikation

Arnold, N.; Palfner, G.; Schmidt, J.; Kuhnt, C.; Becerra, J.; CHEMISTRY OF THE AROMA BOUQUET OF THE EDIBLE MUSHROOM "LEBRE" (Cortinarius lebre, BASDIOMYCOTA, AGARICALES) FROM CHILE J. Chil. Chem. Soc. 57, 1333-1335, (2012) DOI: 10.4067/S0717-97072012000300029

Cortinarius lebre Garrido, a common edible mushroom from central Chile, is distinct from other Cortinarii by its strong, naphtalene-like smell. The relevant volatile compounds were detected by gas chromatography - mass spectrometry and identified as indole together with 1-octen-3-ol, octane-3-one, and octan-3-ol.
Publikation

Teichert, A.; Lübken, T.; Schmidt, J.; Kuhnt, C.; Huth, M.; Porzel, A.; Wessjohann, L.; Arnold, N.; Determination of β‐carboline alkaloids in fruiting bodies of Hygrophorus spp. by liquid chromatography/electrospray ionisation tandem mass spectrometry Phytochem. Anal. 19, 335-341, (2008) DOI: 10.1002/pca.1057

The β ‐carboline alkaloids harmane (1 ) and norharmane (2 ) were isolated from fruiting bodies of Hygrophorus eburneus (Bull.) Fr. as well as brunnein A (3 ) from Hygrophorus hyacinthinus Quél. (Tricholomataceae, Agaricales) for the first time. Their occurrence within the genus was investigated using liquid chromatography/electrospray ionisation tandem mass spectrometric methods, especially by selected reaction monitoring. Based on these results their chemotaxonomical relevance is discussed.
Publikation

Arnold, N.; Schmidt, J.; Kuhnt, C.; Wessjohann, L.; Lukten hos naftalinskinnet, Scytinostroma portentosum Svensk Mykologisk Tidskrift 28, 49-53, (2007)

The naphthalene-like smell of Scytinostroma portentosum (Berk. & Curt.) Donk originates predominantly from indole (1) together with 3-chloroindole (3) and to a lesser extent of 1-octen-3-ol (9). Naphthalene (8) itself could not be detected.
Publikation

Schmidt, J.; Boettcher, C.; Kuhnt, C.; Kutchan, T. M.; Zenk, M. H.; Poppy alkaloid profiling by electrospray tandem mass spectrometry and electrospray FT-ICR mass spectrometry after [ring-13C6]-tyramine feeding Phytochemistry 68, 189-202, (2007) DOI: 10.1016/j.phytochem.2006.10.003

Papaver alkaloids play a major role in medicine and pharmacy. In this study, [ring-13C6]-tyramine as a biogenetic precursor of these alkaloids was fed to Papaver somniferum seedlings. The alkaloid pattern was elucidated both by direct infusion high-resolution ESI-FT-ICR mass spectrometry and liquid chromatography/electrospray tandem mass spectrometry. Thus, based on this procedure, the structure of about 20 alkaloids displaying an incorporation of the labeled tyramine could be elucidated. These alkaloids belong to different classes, e.g. morphinan, benzylisoquinoline, protoberberine, benzo[c]phenanthridine, phthalide isoquinoline and protopine. The valuable information gained from the alkaloid profile demonstrates that the combination of these two spectrometric methods represents a powerful tool for evaluating biochemical pathways and facilitates the study of the flux of distant precursors into these natural products.
Publikation

Li, S.-M.; Westrich, L.; Schmidt, J.; Kuhnt, C.; Heide, L.; Methyltransferase genes in Streptomyces rishiriensis: new coumermycin derivatives from gene-inactivation experiments Microbiol. 148, 3317-3326, (2002) DOI: 10.1099/00221287-148-10-3317

The coumarin antibiotic coumermycin A1 contains at least eight methyl groups, presumably derived from S-adenosylmethionine. Two putative methyltransferase genes, couO and couP, of the coumermycin A1 biosynthetic gene cluster were inactivated by in-frame deletion. In the resulting mutants, coumermycin A1 production was abolished. New coumermycin derivatives were accumulated instead, and were identified by HPLC-MS using selected reaction monitoring via electrospray ionization. couO mutants accumulated a coumermycin derivative lacking the methyl groups at C-8 of the characteristic aminocoumarin rings, whereas in the couP mutant a coumermycin derivative lacking the methyl groups at the 4-hydroxyl groups of the two deoxysugar moieties was identified. These results provided evidence that couO encodes a C-methyltransferase responsible for the transfer of a methyl group to C-8 of the aminocoumarin ring, and couP an O-methyltransferase for methylation of 4-OH of the sugar in the biosynthesis of coumermycin A1, respectively. C-methylation of the aminocoumarin ring is considered as an early step of coumermycin biosynthesis. Nevertheless, the intermediates with the non-methylated aminocoumarin ring were accepted by the enzymes catalysing the subsequent steps of the pathway. The new, demethylated secondary metabolites were produced in an amount at least as high as that of coumermycin A1 in the wild-type.
Publikation

Schrick, K.; Mayer, U.; Martin, G.; Bellini, C.; Kuhnt, C.; Schmidt, J.; Jürgens, G.; Interactions between sterol biosynthesis genes in embryonic development of Arabidopsis Plant J. 31, 61-73, (2002) DOI: 10.1046/j.1365-313X.2002.01333.x

The sterol biosynthesis pathway of Arabidopsis produces a large set of structurally related phytosterols including sitosterol and campesterol, the latter being the precursor of the brassinosteroids (BRs). While BRs are implicated as phytohormones in post‐embryonic growth, the functions of other types of steroid molecules are not clear. Characterization of the fackel (fk ) mutants provided the first hint that sterols play a role in plant embryogenesis. FK encodes a sterol C‐14 reductase that acts upstream of all known enzymatic steps corresponding to BR biosynthesis mutants. Here we report that genetic screens for fk‐like seedling and embryonic phenotypes have identified two additional genes coding for sterol biosynthesis enzymes: CEPHALOPOD (CPH), a C‐24 sterol methyl transferase, and HYDRA1 (HYD1), a sterol C‐8,7 isomerase. We describe genetic interactions between cph , hyd1 and fk , and studies with 15‐azasterol, an inhibitor of sterol C‐14 reductase. Our experiments reveal that FK and HYD1 act sequentially, whereas CPH acts independently of these genes to produce essential sterols. Similar experiments indicate that the BR biosynthesis gene DWF1 acts independently of FK , whereas BR receptor gene BRI1 acts downstream of FK to promote post‐embryonic growth. We found embryonic patterning defects in cph mutants and describe a GC–MS analysis of cph tissues which suggests that steroid molecules in addition to BRs play critical roles during plant embryogenesis. Taken together, our results imply that the sterol biosynthesis pathway is not a simple linear pathway but a complex network of enzymes that produce essential steroid molecules for plant growth and development.
Publikation

Schrick, K.; Mayer, U.; Horrichs, A.; Kuhnt, C.; Bellini, C.; Dangl, J.; Schmidt, J.; Jürgens, G.; FACKEL is a sterol C-14 reductase required for organized cell division and expansion in Arabidopsis embryogenesis Genes Dev. 14, 1471-1484, (2000) DOI: 10.1101/gad.14.12.1471

In flowering plants, the developing embryo consists of growing populations of cells whose fates are determined in a position-dependent manner to form the adult organism. Mutations in the FACKEL(FK) gene affect body organization of theArabidopsis seedling. We report that FK is required for cell division and expansion and is involved in proper organization of the embryo. We isolated FK by positional cloning. Expression analysis in embryos revealed that FK mRNA becomes localized to meristematic zones. FK encodes a predicted integral membrane protein related to the vertebrate lamin B receptor and sterol reductases across species, including yeast sterol C-14 reductase ERG24. We provide functional evidence that FK encodes a sterol C-14 reductase by complementation of erg24. GC/MS analysis confirmed that fk mutations lead to accumulation of intermediates in the biosynthetic pathway preceding the C-14 reductase step. Although fk represents a sterol biosynthetic mutant, the phenotype was not rescued by feeding with brassinosteroids (BRs), the only plant sterol signaling molecules known so far. We propose that synthesis of sterol signals in addition to BRs is important in mediating regulated cell growth and organization during embryonic development. Our results indicate a novel role for sterols in the embryogenesis of plants.
Publikation

Franke, K.; Kuhnt, C.; Schmidt, J.; Muñoz, O.; 24-Epi-castasterone and phytosterols from seeds of Maytenus boaria (Celastraceae) Rev. Latinoam. Quím. 27, 111-115, (2000)

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