Cytochalasins from endophytic <i>Diaporthe</i> sp. GDG-118

Abstract

The plant <i>Sophora tonkinensis</i>, possessed a range of active compounds, was traditionally used in the medicine of Chinese minorities. Endophytic fungi were isolated from this plant, of which the fungus <i>Diaporthe</i> sp. GDG-118 was fermented and extracted with methanol. The extract was screened by antifungal and antibacterial assays leading to the discovery of two new 21-acetoxycytochalasins (<b>1-2</b>) and five known cytochalasins (<b>3-7</b>). These two new compounds were elucidated by spectroscopic analyses, and further their absolute configurations were determined by the X-ray of compound <b>3</b> and comparing their experimental CD spectra. The antibacterial and antifungal effects of these compounds were evaluated. Compound <b>2</b> showed significant inhibitory activity against <i>Bacillus anthraci</i> and <i>Escherichia coli</i> with MIC value of 12.5 μg/mL, and <b>7</b> showed strong antifungal activity against <i>Alternaria oleracea</i>, <i>Pestalotiopsis theae</i> and <i>Colletotrichum capsici</i> with MIC values of 3.125, 1.56 and 1.56 μg/mL, respectively.