Microbial transformation of kawain and methysticin.

The styryl alpha-pyrones, d-kawain (1) and d-methysticin (2) are two of the major kavalactone constituents of the anxiolvtic herb Piper methysticum, commonly known as kava. The use of fungal models to mimic the mammalian metabolism of 1 resulted in the production of 4'-hydroxykawain (1a) from the culture broth of Cunninghamella elegans (ATCC 9245), the same metabolite identified in rat urine. The fungus Torulopsis petrophilum (ATCC 20225) biotransformed 2 to 3'-hydroxy-4'-methoxykawain (2c) which is analogous, but not identical, to a known rat metabolite of methysticin.