Eremophilane-Type Sesquiterpenoids from Fungus Aspergillus aurantiobrunneus

Six previously undescribed sesquiterpenoids, aurantiophilanes A-F (<b>1</b>-<b>6</b>), along with six identified analogues (<b>7</b>-<b>12</b>), were isolated from the fungus <i>Aspergillus aurantiobrunneus</i>. Among these, compounds <b>1</b> and <b>3</b> were identified as highly oxygenated eremophilane sesquiterpenoids, with compound <b>1</b> featuring a rare ketone functional group at C-1. The structures of all compounds were unambiguously elucidated using comprehensive spectroscopic analyses, including HRESIMS, NMR, and UV spectroscopy, supplemented by electronic circular dichroism (ECD) analyses and single-crystal X-ray diffraction. All identified compounds were evaluated for immunosuppressive activity; none showed significant effects at concentrations up to 40 µM.