Antiviral and cytotoxic indole diterpenoids from the antarctic sponge-derived fungus Aspergillus candidus HDN15-152

One new indole diterpenoid, ascandinine T (1), and three known analogues (2–4) were isolated from an Antarctic sponge-derived fungus Aspergillus candidus HDN15-152. The structures, including absolute configurations, were established based on NMR, HRESIMS, and electronic circular dichroism (ECD) calculations. All isolated compounds were tested for antiviral and anticancer activity. Compound 4 displayed antiviral activity against influenza A virus (IAV) of A/PR/8/34(H1N1) strain with an IC₅₀ value of 39.2 μM, while compound 2 showed cytotoxicity against NCI-H446, NCI-H446/EP and L-02 cells with IC₅₀ values ranging from 9.77 to 13.91 μM.