Cytotoxic Ergosteroids from a Strain of the Fungus <i>Talaromyces adpressus</i>

Abstract

Nine new ergosteroids (<b>1</b>-<b>9</b>) and seven known ones (<b>10</b>-<b>16</b>) were isolated from <i>Talaromyces adpressus</i>. Their structures and absolute configurations were determined by the interpretation of NMR spectroscopic data, HRESIMS, ECD calculations, and single-crystal X-ray diffraction analyses. Structurally, compound <b>1</b> was an ergosteroid with two epoxy and a 3<i>α</i>-OH group at ring A, while compounds <b>8</b> and <b>9</b> had a contracted ring A with a peroxy bridge between C-3 and C-9, which were reported for the first time. Compounds <b>2</b>-<b>6</b>, <b>9</b>, <b>11</b>, and <b>15</b> displayed cytotoxic activities with IC₅₀ values ranging from 0.4 to 32 <i>μ</i>M, and compound <b>7</b> exhibited an immunosuppressive effect against LPS-induced B lymphocyte proliferation with an IC₅₀ value of 8.6 <i>μ</i>M. The structure-activity relationships of these compounds are briefly discussed.