Structure revision of tricholomenyn B, an antimitotic geranylcyclohexenone rediscovered as a bitter and antibacterial substance, from a basidiomycete Tricholoma japonicum (Shiro-shimeji)

Tricholomenyn B, an antimitotic geranylcyclohexenone originally discovered from a basidiomycete Tricholoma acerbum, was isolated as a bitter and antibacterial constituent from fruiting bodies of T. japonicum. Careful comparison of NMR, MS, and other physicochemical properties of the isolated substance with the literature values revised a previously proposed macrolide structure 1 to a macrodiolide 2. Compound 2 was perceived bitter at a minimum dose of 37.5 μg, showed weak antimicrobial activity against Kocuria rhizophila and Staphylococcus aureus, and was marginally cytotoxic (IC50 2.6 µM) against P388 murine leukemia cells.