Talaroterpenoids A–F: Six New Seco-Terpenoids from the Marine-Derived Fungus Talaromyces aurantiacus

Six new highly oxidized <i>seco</i>-terpenoids, including three 3-<i>nor</i>-labdane type diterpenes, talaroterpenoids A-C (<b>1</b>-<b>3</b>), and three meroterpenoids containing an orthoester group, talaroterpenoids D-F (<b>6</b>-<b>8</b>), together with five known compounds (<b>4</b>-<b>5</b> and <b>9</b>-<b>11</b>), were isolated from the marine-derived fungus <i>Talaromyces aurantiacus</i>. Their chemical structures were elucidated through 1D, 2D NMR, HRESIMS, <i>J</i>-based configuration analysis (JBCA), computational ECD calculations, and single-crystal X-ray diffraction analysis. Compounds <b>1</b> and <b>2</b> contain an unusual 6,20-<i>γ</i>-lactone-bridged scaffold. Compounds <b>10</b> and <b>11</b> presented inhibitory effects on NO release in lipopolysaccharide (LPS)-induced BV-2 cells with IC₅₀ values of 11.47 and 11.32 μM, respectively. Talaroterpenoid C (<b>3</b>) showed moderate antifungal activity against <i>A. alternata</i> and <i>P. theae</i> Steyaert.