Polyellisin, a novel polyketide from cultures of the basidiomycete Polyporus ellisii .

Polyellisin (1), an unprecedented polyketide possessing a tricyclic system sharing a spiroketal carbon, was isolated from cultures of the basidiomycete Polyporus ellisii . The structure with absolute configuration was elucidated by means of spectroscopic methods and the single crystal X-ray diffraction. Polyellisin showed NO production inhibition with an IC 50 value of 17.2 μM.