A new bioactive diterpenoid from <i>pestalotiopsis adusta</i>, an endophytic fungus from <i>clerodendrum canescens</i>

<p>Bioassay-guided fractionation of the culture extract of <i>Pestalotiopsis adusta</i>, an endophytic fungus isolated from the medicinal plant <i>Clerodendrum canescens</i>, led to the isolation of one new, (10<i>S</i>)-12,16-epoxy-17(15→16)-abeo-3,5,8,12,15-abietapentaen-2,7,11,14-tetraone (<b>1</b>), and four known diterpenoids, teuvincenone F (<b>2</b>), uncinatone (<b>3</b>), coleon U (<b>4</b>), coleon U-12-methyl ether (<b>5</b>). These structures were identified by using spectroscopic methods, including UV, MS, 1D and 2D NMR experiments. This is the first report of these compounds being isolated from a <i>Pestalotiopsis</i> species. The cytotoxic activities of the compounds were evaluated, and compounds <b>1</b> and <b>3</b> demonstrated cytotoxic activities against the HL-60 tumour cell line (IC<sub>50</sub> < 20 μM).</p>