Epoxyexserohilone, a Novel Metabolite from Nigrospora sphaerica

Fermentation of Nigrospora sphaerica on shredded wheat medium generated the novel metabolite, epoxyexserohilone, a congener of the known phytotoxin, exserohilone. Single crystal X-ray diffraction determined the structure and absolute stereochemistry of this metabolite which had the molecular formula C20H22N2O6S2, melting point 190–192°C, and an EI-MS identical with its congener exserohilone. The metabolite did not exhibit biological activity in an etiolated wheat coleoptile bioassay, neither was it active against Gram-positive or Gram-negative bacteria.