Omanische Heilpflanze im Fokus der Phytochemie IPB-Wissenschaftler und Partner aus Dhofar haben jüngst die omanische Heilpflanze Terminalia dhofarica unter die phytochemische Lupe genommen. Die Pflanze ist reich an…
Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
Otto, A.; Porzel, A.; Schmidt, J.; Wessjohann, L.; Arnold, N.;A study on the biosynthesis of hygrophorone B12 in the mushroom Hygrophorus abieticola reveals an unexpected labelling pattern in the cyclopentenone moietyPhytochemistry118174-180(2015)DOI: 10.1016/j.phytochem.2015.08.018
The hitherto unknown natural formation of hygrophorones, antibacterial and antifungal cyclopentenone derivatives from mushrooms, was investigated for hygrophorone B12 in Hygrophorus abieticola Krieglst. ex Gröger & Bresinsky by feeding experiments in the field using 13C labelled samples of d-glucose and sodium acetate. The incorporation of 13C isotopes was extensively studied using 1D and 2D NMR spectroscopy as well as ESI-HRMS analyses. In the experiment with [U-13C6]-glucose, six different 13C2 labelled isotopomers were observed in the 2D INADEQUATE spectrum due to incorporation of [1,2-13C2]-acetyl-CoA. This labelling pattern demonstrated that hygrophorone B12 is derived from a fatty acid-polyketide route instead of a 1,4-α-d-glucan derived anhydrofructose pathway. The experiment with [2-13C]-acetate revealed an unexpected incorporation pattern in the cyclopentenone functionality of hygrophorone B12. Four single-labelled isotopomers, in particular [1-13C]-, [2-13C]-, [3-13C]-, and [4-13C]-hygrophorone B12, were detected that showed only half enrichment in comparison to the respective labelled alkyl side chain carbons. This labelling pattern indicates the formation of a symmetrical intermediate during hygrophorone B12 biosynthesis. Based on these observations, a biogenetic route via a 4-oxo fatty acid and a chrysotrione B homologue is discussed.
Publikation
Tanemossu, S. A. F.; Franke, K.; Arnold, N.; Schmidt, J.; Wabo, H. K.; Tane, P.; Wessjohann, L. A.;Rare biscoumarin derivatives and flavonoids from Hypericum ripariumPhytochemistry105171-177(2014)DOI: 10.1016/j.phytochem.2014.05.008
Hypericum riparium A. Chev. is a Cameroonian medicinal plant belonging to the family Guttiferae. Chemical investigation of the methanol extract of the stem bark of H. riparium led to the isolation of four natural products, 7,7′-dihydroxy-6,6′-biscoumarin (1), 7,7′-dihydroxy-8,8′-biscoumarin (2), 7-methoxy-6,7′-dicoumarinyl ether (3), 2′-hydroxy-5′-(7″-methoxycoumarin-6″-yl)-4′-methoxyphenylpropanoic acid (4), together with one known 7,7′-dimethoxy-6,6′-biscoumarin (5), two flavones, 2′-methoxyflavone (6) and 3′-methoxy flavone (7), and two steroids, stigmast-4-en-3-one (8) and ergosta-4,6,8,22-tetraen-3-one (9). In addition, tetradecanoic acid (10), n-pentadecanoic acid (11), hexadecanoic acid (12), cis-10-heptadecenoic acid (13), octadecanoic acid (14) campesterol (15), stigmasterol (16), β-sitosterol (17), stigmastanol (18), β-eudesmol (19), 1-hexadecanol (20), and 1-octadecanol (21) were identified by GC–MS analysis. Compound 4 consists of a phenylpropanoic acid derivative fused with a coumarin unit, while compounds 2 and 3 are rare members of C8–C8′ and C7–O–C6 linked biscoumarins. Their structures were elucidated by UV, IR, extensive 1D- and 2D-NMR experiments and electrospray (ESI) high resolution mass spectrometry (MS) including detailed MS/MS studies. This is the first report on the isolation of biscoumarins from the genus Hypericum, although simple coumarin derivatives have been reported from this genus in the literature. The cytotoxic activities of compounds 2–5 were evaluated against the human prostate cancer cell line PC-3 and the colon cancer cell line HT-29. They do not exhibit any significant cytotoxic activity.
Five sesquiterpene carboxylic acids (1–5) and one nor-sesquiterpene carboxylic acid (6) of the very rare ventricosane type, named penarines A–F, were isolated from fruiting bodies of the basidiomycete Hygrophorus penarius (Hygrophoraceae). This is the first report of (nor)-sesquiterpenes isolated from basidiocarps of the family Hygrophoraceae. Their structures were elucidated on the basis of extensive 1D (1H, 13C) and 2D (HSQC, HMBC, COSY, ROESY) NMR spectroscopic analyses as well as high-resolution mass spectrometry studies. Additionally, the only known member of this rare type of sesquiterpenes, ventricos-7(13)-ene (7), could be identified via headspace GC–MS analysis in a fruiting body of H. penarius. Compounds 1–6 were devoid of remarkable antifungal activity against Cladosporium cucumerinum. Additionally, the cytotoxic activities of compounds 1 and 2 were evaluated against the human prostate cancer cell line PC-3 and the colon cancer cell line HT-29 showing no significant cytotoxic activity.
Publikation
Günnewich, N.; Higashi, Y.; Feng, X.; Choi, K.-B.; Schmidt, J.; Kutchan, T. M.;A diterpene synthase from the clary sage Salvia sclarea catalyzes the cyclization of geranylgeranyl diphosphate to (8R)-hydroxy-copalyl diphosphatePhytochemistry9193-99(2013)DOI: 10.1016/j.phytochem.2012.07.019
The bicyclic diterpene (−)-sclareol is accumulated in glandular trichomes in Salvia sclarea (Schmiderer et al., 2008), and is a major terpenoid component of this plant species. It is used as the starting material for Ambrox synthesis, a synthetic ambergris analog used in the flavor and fragrance industry. In order to investigate the formation of sclareol, cDNA prepared from secretory cells of glandular trichomes from S. sclarea inflorescence were randomly sequenced. A putative copalyl diphosphate synthase encoding EST, SscTPS1, was functionally expressed in Escherichia coli. Whereas reaction of geranylgeranyl diphosphate with the putative copalyl diphosphate synthase followed by hydrolysis with alkaline phosphatase yielded a diastereomeric mixture of (13R)- and (13S)-manoyl oxide, HCl hydrolysis yielded (−)-sclareol (1) and 13-epi-sclareol as products. The product of the reaction of SscTPS1 with geranylgeranyl diphosphate was subjected to analysis by LC-negative ion ESI-MS/MS without prior hydrolysis. EPI scans were consistent with copalyl diphosphate to which 18 mass units had added (m/z 467 [M+H]−). The enzymatic reaction was also carried out in the presence of 60% H218O. LC-negative ion ESI-MS/MS analysis established an additional reaction product consistent with the incorporation of 18O. Incubation in the presence of 60% 2H2O resulted in the incorporation of one deuterium atom. These results suggest water capture of the carbocation intermediate, which is known to occur in reactions catalyzed by monoterpene synthases, but has been described only several times for diterpene synthases.