Antiviral and antiplasmodial spirodihydrobenzofuran terpenes from the fungus Stachybotrys nephrospora.

Two known spirodihydrobenzofuran terpenes (1 and 2) were isolated from a mycelium extract of the fungus Stachybotrys nephrospora BCC 3900. Compound 1 (Mer-NF5003F or stachybotrydial) exhibited potent antiviral activity (the IC50 value of 4.32 microg/mL) comparable to the standard drug, acyclovir, while compound 2 was inactive against the HSV-1 virus. Both 1 and 2 possessed antiplasmodial activity (IC50 values of 0.85 and 0.15 microg/mL for 1 and 2, respectively), and were not toxic towards the Vero cell line. A regiospecific conversion of the dialdehyde 1 to the lactone 2 proceeded simply under acidic conditions.