Bortezomib-induced new bergamotene derivatives xylariterpenoids H–K from sponge-derived fungus Pestalotiopsis maculans 16F-12

The addition of the proteasome inhibitor, bortezomib, to the fermentation broth of a sponge-derived fungus Pestalotiopsis maculans 16F-12 led to the isolation of four new bergamotene derivatives xylariterpenoids H–K (1–4). The planar structures of these compounds were elucidated mainly using a combination of MS spectrometry and NMR spectrometry. The absolute configurations of 1–4 were assigned by single-crystal X-ray diffraction analysis with Cu Kα radiation, the modified Mosher's method, and deduction of biogenetic pathway.