AUTHOR=Silber Johanna , Ohlendorf Birgit , Labes Antje , Wenzel-Storjohann Arlette , Näther Christian , Imhoff Johannes F. 

TITLE=Malettinin E, an antibacterial and antifungal tropolone produced by a marine Cladosporium strain

JOURNAL=Frontiers in Marine Science

VOLUME=1

YEAR=2014

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2014.00035

DOI=10.3389/fmars.2014.00035

ISSN=2296-7745

ABSTRACT=<p>The isolation and structure elucidation of malettinins A–C (<bold>1</bold>–<bold>3</bold>) along with the new malettinin E (<bold>4</bold>) are described. The compounds were produced by the fungus <italic>Cladosporium</italic> sp. strain KF501, which was isolated from the German Wadden Sea. The malettinins are built up of tropolone/dihydropyran ring structures linked to a furan ring. The structure elucidation of the isolated compounds was achieved by means of one- and two-dimensional NMR spectroscopy supported by mass and UV data. The relative configuration of <bold>4</bold> was determined on the basis of single-crystal X-ray diffraction analysis. <bold>1</bold>–<bold>4</bold> exhibited antibacterial and antifungal activities when profiled against <italic>Xanthomonas campestris</italic> and <italic>Trichophyton rubrum</italic>. The influence of the chemical structure of the furan ring and of configurational changes on biological activities was observed.</p>