Kongens Lyngby, Denmark
Kongens Lyngby, Denmark

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Ronnest M.H.,Technical University of Denmark | Ronnest M.H.,Center for Microbial Biotechnology | Nielsen M.T.,Center for Microbial Biotechnology | Leber B.,University of Heidelberg | And 5 more authors.
Acta Crystallographica Section C: Crystal Structure Communications | Year: 2011

The fungal metabolite (+)-geodin [systematic name: (2R)-methyl 5,7-dichloro-4-hy-droxy-6′-meth-oxy-6-methyl-3,4′-di-oxo-spiro- [benzofuran-2,1′-cyclo-hexa-2′,5′-diene]-2′-carboxyl- ate], C 17H 12Cl 2O 7, was isolated from Aspergillus terreus. The crystal structure contains two independent mol-ecules in the asymmetric unit. Mol-ecules denoted 1 inter-act through O - H⋯O hydrogen bonds creating chains of mol-ecules parallel to the crystallographic 2 1 screw axis. Mol-ecules denoted 2 inter-act through an O⋯Cl halogen bond, also creating chains of mol-ecules parallel to the crystallographic 2 1 screw axis. Mol-ecules 1 and 2 inter-act through another O⋯Cl halogen bond. The two mol-ecules are similar but mol-ecules 2 have a slightly more planar cyclohexadiene ring than mol-ecules 1. The absolute structure of (+)-geodin has been unequivocally assigned with the spiro centre having the R configuration in both mol-ecules. The structurally related (+)-griseofulvin has an S configuration at the spiro centre, a difference of potential biological and biosynthetic relevance. © 2011 International Union of Crystallography.


Ronnest M.H.,Center for Nanomedicine and Theranostics | Nissen F.,University of Heidelberg | Pedersen P.J.,Center for Nanomedicine and Theranostics | Larsen T.O.,Center for Microbial Biotechnology | And 2 more authors.
European Journal of Organic Chemistry | Year: 2013

A novel technique to label ortho-, meta-, and para-trimethylsilyl- substituted aryl substituents with radioactive iodide is described. The method takes advantage of the ipso-directing and activating properties of trimethylsilyl substituents on the arenes. The method was demonstrated on a griseofulvin analogue with promising anticancer properties and on lidocaine, a widely used local anesthetic drug. Treatment of a trimethylsilyl precursor with Tl(OCOCF3)3 followed by Na125I consistently afforded radioactive purities over 95 % in all cases. A mild and selective method for radioiodination of aromatic compounds is described. This method is used to label three regioisomers of an analogue of griseofulvin with potent anticancer activity. The method takes advantage of the ipso-directing effect of a trimethylsilyl (TMS) substituent and is also demonstrated to work for the local anesthetic lidocaine. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Phipps R.K.,Center for Microbial Biotechnology | Gotfredsen C.H.,Technical University of Denmark | Paludan S.R.,Wilhelm Meyers Alle | Frisvad J.C.,Center for Microbial Biotechnology | And 4 more authors.
Tetrahedron Letters | Year: 2011

Six new meroterpenoid compounds, hesseltins B-G, were isolated from Penicillium species along with the previously described hesseltin A. A further 14 compounds, which turned out to be photoisomers, were detected during purification and were subsequently isolated. The structures of these analogues were elucidated by comparison of their NMR spectral data with that of hesseltin A. None of the new hesseltins showed antiviral activity in a Herpes simplex virus type 2 assay. © 2010 Elsevier Ltd. All rights reserved.


Ronnest M.H.,Technical University of Denmark | Ronnest M.H.,Center for Microbial Biotechnology | Harris P.,Technical University of Denmark | Gotfredsen C.H.,Technical University of Denmark | And 2 more authors.
Tetrahedron Letters | Year: 2010

The two phenols, 6-O-desmethyl griseofulvin and 4-O-desmethyl griseofulvin are metabolites of the antifungal drug griseofulvin. Herein, we present an improved synthesis of the 6-phenol derivative, and an unequivocal proof of both structures by single-crystal X-ray analysis. © 2010 Elsevier Ltd. All rights reserved.

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