Antioxidant metabolites from the endophytic fungus Aspergillus spelaeus

Five undescribed compounds, including two drimane-type sesquiterpenoids, asperdrimanes A and B (1 and 2), and three amide compounds, asperspamides A-C (3-5), together with four known metabolites 6-9, were isolated from the fungus Aspergillus spelaeus GDGJ-286. By extensively analyzing NMR, LC-MS/MS, Marfey's method, and X-ray crystallography, the structures were characterized successfully. Asperdrimanes A and B (1 and 2) are drimane-type sesquiterpenoids characterized by a spiro-β-lactone moiety. Asperspamide B (4) exhibited exceptional antioxidant capacity in ABTS, FRAP, and DPPH tests, along with significant neuroprotective effects in a hydrogen peroxide-induced PC12 cell oxidative injury model, demonstrating strong anti-apoptotic and anti-necrotic properties. These findings highlight asperspamide B's potential as a lead compound for developing antioxidant agents.