Undescribed cytotoxic bisabosqual-type meroterpenoids from an endophytic Stachybotryaceae sp. associated with Delphinium yunnanense.

Five undescribed bisabosqual-type meroterpenoids, bisabosquals E (1) and F (2), stachybisbins J-L (4-6), together with two known ones, were isolated from a novel endophytic fungus KMU22001 within the Stachybotryaceae family. Their structures with absolute configurations were elucidated by detailed interpretation of NMR spectroscopy, mass spectrometry, single-crystal X-ray diffraction and electronic circular dichroism calculations. Compounds 2, 4 and 6 exhibited significant cytotoxicities against five human cancer cell lines with IC50 values ranging from 1.80 ± 0.08 to 17.76 ± 0.97 μM.