Trypethelone and phenalenone derivatives isolated from the mycobiont culture of <i>Trypethelium eluteriae</i> Spreng. and their anti-mycobacterial properties

<p>The metabolites of the mycobiont culture of the lichen <i>Trypethelium eluteriae</i> were isolated by column chromatography and preparative TLC. Nine compounds (<b>1</b>–<b>9</b>) including two new trypethelones, 8-methoxytrypethelone (<b>6</b>) and 5′-hydroxy-8-ethoxytrypethelone (<b>9</b>), together with four known trypethelones (<b>3</b>–<b>4</b>, <b>7</b>–<b>8</b>), and two known phenalenones (<b>1</b>–<b>2</b>) were characterized. It is the first report of 8-methoxytrypethelone methyl ether (<b>5</b>) purification as a racemic mixture in <i>T. eluteriae</i>. Earlier, 7-hydroxyl-8-methoxyltrypethelone (<b>10</b>) was reported as new compound with erroneous spectroscopic data. This compound was identified later as 8-hydroxytrypethelone methyl ether (<b>4</b>). X-ray crystallographic structures of compounds <b>5</b>–<b>7</b> were elucidated for the first time. Phenalenones (<b>1</b>–<b>2</b>) and trypethelones (<b>5</b>–<b>6</b> and <b>9</b>) were the additional compounds discovered in the cultured mycobiont of <i>T. eluteriae</i>. Six compounds (<b>1</b>–<b>2</b>, <b>5</b>–<b>8</b>) were screened against <i>Mycobacterium tuberculosis</i> H37Rv and two compounds (<b>7</b>–<b>8</b>) against non-tuberculosis mycobacteria and other human pathogenic bacteria. Compound (<b>7</b>) inhibited <i>M. tuberculosis</i> H37Rv strain with an MIC of 12.5 µg/mL.</p>