Bistachybotrysins A-C, three phenylspirodrimane dimers with cytotoxicity from Stachybotrys chartarum.

Bistachybotrysins A-C (1-3), three phenylspirodrimane dimers representing an unusual [6,6,7,6]-tetracyclic skeleton with a central 2,10-dioxabicyclo[4.3.1]decan-7-ol core fused with two phenyl units, were isolated from a fungal strain, Stachybotrys chartarum CGMCC 3.5365. The structures of 1-3 were elucidated through extensive spectroscopic data analysis, including Mo2(AcO)4-induced and calculated electronic circular dichroism (ECD). 1 and 2 exhibited potent cytotoxicity against four human tumor cell lines with IC50 values in the range of 2.8-7.5 μM. Furthermore, a possible biogenesis for 1-3 is proposed.