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Publikation

Lam, Y. T. H.; Hoppe, J.; Dang, Q. N.; Porzel, A.; Soboleva, A.; Brandt, W.; Rennert, R.; Hussain, H.; Davari, M. D.; Wessjohann, L.; Arnold, N.; Purpurascenines A–C, azepino-indole alkaloids from Cortinarius purpurascens: Isolation, biosynthesis, and activity studies on the 5-HT2A receptor J. Nat. Prod. 86, 1373-1384, (2023) DOI: 10.1021/acs.jnatprod.2c00716

Three previously undescribed azepino-indole alkaloids, named purpurascenines A−C (1−3), together with the new-to-nature 7-hydroxytryptophan (4) as well as two known compounds, adenosine (5) and riboflavin (6), were isolated from fruiting bodies of Cortinarius purpurascens Fr. (Cortinariaceae). The structures of 1−3 were elucidated based on spectroscopic analyses and ECD calculations. Furthermore, the biosynthesis of purpurascenine A (1) was investigated by in vivo experiments using 13C-labeled sodium pyruvate, alanine, and sodium acetate incubated with fruiting bodies of C. purpurascens. The incorporation of 13C into 1 was analyzed using 1D NMR and HRESIMS methods. With [3-13C]-pyruvate, a dramatic enrichment of 13C was observed, and hence a biosynthetic route via a direct Pictet−Spengler reaction between α-keto acids and 7-hydroxytryptophan (4) is suggested for the biosynthesis of purpurascenines A−C (1−3). Compound 1 exhibits no antiproliferative or cytotoxic effects against human prostate (PC-3), colorectal (HCT-116), and breast (MCF-7) cancer cells. An in silico docking study confirmed the hypothesis that purpurascenine A (1) could bind to the 5-HT2A serotonin receptor’s active site. A new functional 5-HT2A receptor activation assay showed no functional agonistic but some antagonistic effects of 1 against the 5-HT-dependent 5-HT2A activation and likely antagonistic effects on putative constitutive activity of the 5-HT2A receptor.
Publikation

Lam, Y. T. H.; Ricardo, M. G.; Rennert, R.; Frolov, A.; Porzel, A.; Brandt, W.; Stark, P.; Westermann, B.; Arnold, N.; Rare glutamic acid methyl ester peptaibols from Sepedonium ampullosporum Damon KSH 534 exhibit promising antifungal and anticancer activity Int. J. Mol. Sci. 22, 12718, (2021) DOI: 10.3390/ijms222312718

Fungal species of genus Sepedonium are rich sources of diverse secondary metabolites (e.g., alkaloids, peptaibols), which exhibit variable biological activities. Herein, two new peptaibols, named ampullosporin F (1) and ampullosporin G (2), together with five known compounds, ampullosporin A (3), peptaibolin (4), chrysosporide (5), c(Trp-Ser) (6) and c(Trp-Ala) (7), have been isolated from the culture of Sepedonium ampullosporum Damon strain KSH534. The structures of 1 and 2 were elucidated based on ESI-HRMSn experiments and intense 1D and 2D NMR analyses. The sequence of ampullosporin F (1) was determined to be Ac-Trp1-Ala2-Aib3-Aib4-Leu5-Aib6-Gln7-Aib8-Aib9-Aib10-GluOMe11-Leu12-Aib13-Gln14-Leuol15, while ampullosporin G (2) differs from 1 by exchanging the position of Gln7 with GluOMe11. Furthermore, the total synthesis of 1 and 2 was carried out on solid-phase to confirm the absolute configuration of all chiral amino acids as L. In addition, ampullosporin F (1) and G (2) showed significant antifungal activity against B. cinerea and P. infestans, but were inactive against S. tritici. Cell viability assays using human prostate (PC-3) and colorectal (HT-29) cancer cells confirmed potent anticancer activities of 1 and 2. Furthermore, a molecular docking study was performed in silico as an attempt to explain the structure-activity correlation of the characteristic ampullosporins (1–3).
Publikation

Ditfe, T.; Bette, E.; N. Sultani, H.; Otto, A.; Wessjohann, L. A.; Arnold, N.; Westermann, B.; Synthesis and biological evaluation of highly potent fungicidal deoxy‐hygrophorones Eur. J. Org. Chem. 2021, 3827-3836, (2021) DOI: 10.1002/ejoc.202100729

Although stripped from hydroxyl-groups, deoxygenated hygrophorones remain highly active against severe phytopathogens. The synthesis to these natural product congeners is achieved in rearrangement sequences, with an optimized deprotection strategy avoiding retro-aldol reactions. The activities are comparable to fungicides used in agriculture. Based on naturally occurring hygrophorones, racemic di- and mono-hydroxylated cyclopentenones bearing an aliphatic side chain have been produced in short synthetic sequences starting from furfuryl aldehyde. For the series of dihydroxylated trans-configured derivatives, an Achmatowicz-rearrangement and a Caddick-ring contraction were employed, and for the series of trans-configured mono-hydroxylated derivatives a Piancatelli-rearrangement. All final products showed good to excellent fungicidal activities against the plant pathogens B. cinerea, S. tritici and P. infestans.
Publikation

Palfner, G.; GALLEGUILLOS, F.; Arnold, N.; CASANOVA-KATNY, A.; HORAK, E.; Sequestrate syndrome in Bondarzewia guaitecasensis (Fungi, Basidiomycota)? The case of Hybogaster giganteus revisited Phytotaxa 474, 272-282, (2020) DOI: 10.11646/phytotaxa.474.3.6

Based on comparison of molecular, morphological and ecological data, we propose that Hybogaster giganteus Singer, a parasitic basidiomycete on stem bases and coarse roots of Nothofagus in Chile, is conspecifically related to the sympatric Bondarzewia guaitecasensis. According to our concept, H. giganteus is representing a sequestrate form of the latter and is hence recombined and formally described as Bondarzewia guaitecasensis f. gigantea; we further discuss the evidence that its sequestrate morphology may provide higher resistance to drought stress in early autumn, extending the sporulation season of the species.
Publikation

Chuankid, B.; Schrey, H.; Thongbai, B.; Raspé, O.; Arnold, N.; Hyde, K. D.; Stadler, M.; Secondary metabolites of Phlebopus species from Northern Thailand Mycol. Prog. 19, 1525-1536, (2020) DOI: 10.1007/s11557-020-01643-y

AbstractSubmerged cultures of the edible mushrooms Phlebopus portentosus and Phlebopus spongiosus were screened for their secondary metabolites by HPLC-UV/Vis and HR-LC-ESI-MS. Two new compounds, 9′-hydroxyphenyl pulvinone (1), containing an unusual pulvinone structure, and phlebopyron (2), together with the seven known pigments, atromentic acid (3), xerocomic acid (4), variegatic acid (5), methyl atromentate (6), methyl isoxerocomate (7), methyl variegatate (8), and variegatorubin (9) were isolated from the cultures. Their structures were assigned on the basis of extensive 1D/2D NMR spectroscopic analyses, as well as HR-ESI-MS, and HR-ESI-MS/MS measurements. Furthermore, the isolated compounds were evaluated for their antimicrobial and cytotoxic properties. 9′-hydroxyphenyl pulvinone (1), xerocomic acid (4), and methyl variegatate (8) exhibited weak to moderate cytotoxic activities against several tumor cell lines. The present paper provides a comprehensive characterization of pigments from the class of pulvinic acids that are present in the basidiomes of many edible bolete species.
Publikation

Tchatchouang Noulala, C. G.; Fotso, G. W.; Rennert, R.; Lenta, B. N.; Sewald, N.; Arnold, N.; Happi, E. N.; Ngadjui, B. T.; Mesomeric form of quaternary indoloquinazoline alkaloid and other constituents from the Cameroonian Rutaceae Araliopsis soyauxii Engl. Biochem. Syst. Ecol. 91, 104050, (2020) DOI: 10.1016/j.bse.2020.104050

A mesomeric form of quaternary indoloquinazoline alkaloid, soyauxinium chloride (1) was obtained through the chemical investigation of stem bark and roots of Araliopsis soyauxii Engl. [syn. Vepris soyauxii (Engl.) Mziray] (Rutaceae) together with fifteen known compounds, including three furoquinoline alkaloids, three 2-quinolones, two limonoids, two triterpenes, two steroids, a coumarin, an acridone alkaloid, and a flavonoid glycoside. Their structures were established by comprehensive spectroscopic and spectrometric analyses (1D and 2D NMR, ESI-HR-MS) and by comparison with previously reported data. 13C NMR data of araliopsinine are also reported here for the first time. The isolated compounds were screened in vitro for their effects on the viability of two different human cancer cell lines, namely prostate PC-3 adenocarcinoma cells and colorectal HT-29 adenocarcinoma cells. However, none of the tested compounds exhibited strong anti-proliferative or cytotoxic activities, to either prostate PC-3 cells or colon HT-29 cells. At 100 μM, the furoquinoline maculine showed a slightly increased anti-proliferative effect, however, exclusively on HT-29 cells. The chemotaxonomic significance of the isolated compounds has also been discussed.
Publikation

Lam, Y. T. H.; Palfner, G.; Lima, C.; Porzel, A.; Brandt, W.; Frolov, A.; Sultani, H.; Franke, K.; Wagner, C.; Merzweiler, K.; Wessjohann, L. A.; Arnold, N.; Nor-guanacastepene pigments from the Chilean mushroom Cortinarius pyromyxa Phytochemistry 165, 112048, (2019) DOI: 10.1016/j.phytochem.2019.05.021

For the first time, the pigment composition of basidiocarps from the Chilean mushroom Cortinarius pyromyxa was studied under various aspects like phylogeny, chemistry and antibiotic activity. A molecular biological study supports the monotypic position of C. pyromyxa in subgenus Myxacium, genus Cortinarius. Four undescribed diterpenoids, named pyromyxones A-D, were isolated from fruiting bodies of C. pyromyxa. Their chemical structures were elucidated based on comprehensive one- and two-dimensional NMR spectroscopic analysis, ESI-HRMS measurements, as well as X-ray crystallography. In addition, the absolute configurations of pyromyxones A-D were established with the aid of JH,H, NOESY spectra and quantum chemical CD calculation. The pyromyxones A-D possess the undescribed nor-guanacastane skeleton. Tested pyromyxones A, B, and D exhibit only weak activity against gram-positive Bacillus subtilis and gram-negative Aliivibrio fischeri as well as the phytopathogenic fungi Botrytis cinerea, Septoria tritici and Phytophthora infestans.
Publikation

Fobofou, S. A. T.; Ares, K.; Arnold, N.; Imming, P.; New source report: Chemical constituents of Hypericum quartinianum (Hypericaceae), a sub-Saharan African plant species Biochem. Syst. Ecol. 85, 46-49, (2019) DOI: 10.1016/j.bse.2019.05.006

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Publikation

Reisberg, M.; Arnold, N.; Bisrat, D.; Asres, K.; Neubert, R. H.; Dräger, B.; Quantification of glycosylceramides in plants by automated multiple development–high-performance thin-layer chromatography JPC - J. Planar Chromat. 30, 460-466, (2017) DOI: 10.1556/1006.2017.30.6.1

Glycosylceramides (GlyCers) are precursors of ceramides (Cers) that are major components of the outer layer of human skin, the stratum corneum. A Cer deficiency is associated with skin diseases such as psoriasis and atopic dermatitis and can be treated with Cer-containing semisolid formulations. Plants may serve as alternative sources for expensive semisynthetic Cer production. Since the GlyCer contents of plants vary widely, there is a need to develop a rapid, simple, selective, and precise method for GlyCer quantification in plants. In the present study, an effective and validated automated multiple development‒high-performance thin-layer chromatography (AMD‒HPTLC) method has been developed for GlyCer quantification in 9 different plant materials. An 18-step gradient elution program (n-hexane, chloroform, ethyl acetate, methanol) led to a clear separation of bands from complex matrices and allowed densitometric analysis for quantification purposes. Apple pomace and wheat germs yielded 26.8 and 39.5 mg of GlyCer per 100 g plant material, respectively, while the yields of coffee grounds were below the limit of quantification. The GlyCer contents of the seeds of six Fabaceae species, namely, Albizia grandibracteata, Albizia gummifera, Albizia lebbeck, Albizia schimperiana, Acacia etbaica, and Robinia pseudoacacia, ranged from 9.4 to 23.1 mg per 100 g plant material. GlyCers were separated by preparative thin-layer chromatography (TLC) and identified by offline high-performance liquid chromatography–mass spectrometry (HPLC–MS). Intact GlyCers were detected in the Fabaceae species for the first time. A simple AMD–HPTLC screening and quantification technique for GlyCers was developed, which may serve as a tool in searching plant GlyCers for a possible “phyto”-Cer production.
Publikation

Greff, A.; Porzel, A.; Schmidt, J.; Palfner, G.; Arnold, N.; Pigment pattern of the Chilean mushroom Dermocybe nahuelbutensis Garrido & E. Horak Rec. Nat. Prod. 11, 547-551, (2017) DOI: 10.25135/rnp.69.17.01.027

Fruiting bodies of the Chilean mushroom Dermocybe nahuelbutenis Garrido & E. Horak (syn.: Cortinariusnahuelbutensis (Garrido & E. Horak) E. Valenz. & G. Moreno) were chemically investigated for the first time andafforded the new dimeric anthraqinone 7,7'-emodinphyscion (1) beside the know anthraquinones dermolutein (2),endocrocin (3), skyrin (4) and the dimeric pre-anthraquinone derivative flavomannin C (5). The chemotaxonomicsignificance of the pigments is discussed.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
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