Pullenvalenes E–H: Triterpenyl-Aminoglycosides from an Australian Soil-Derived Fungus, <i>Clonostachys</i> sp.

Chemical profiling of soil-derived microbes collected under the auspices of the Australian citizen science initiative Soils for Science detected two fungi, <i>Clonostachys</i> sp. S4S-07771A07 and <i>Coccidiodes</i> sp. S4S-14879B01, capable of producing pullenvalenes, a rare class of triterpene glycoside. Cultivation profiling followed by scaled up cultivation and fractionation of the former yielded the known pullenvalenes A-D (<b>1</b>-<b>4</b>) and the new analogues E-H (<b>5</b>-<b>8</b>), with structures secured by detailed spectroscopic analysis and biogenetic considerations. This study reveals that the pullenvalenes <b>1</b>-<b>8</b> are produced by several genera of fungi (<i>Clonostachys</i>, <i>Coccidiodes</i> and <i>Talaromyces</i>) recovered from different geographic locations and substrates. We also draw attention to structural and biosynthetic similarities with the known Red Sea sponge metabolites neviotines A-D (<b>9</b>-<b>12</b>) and abudinols A-B (<b>13</b>-<b>14</b>), prompting speculation that the latter may be products of sponge-associated fungi.