Microbial hydroxylation and reduction of the diterpene psiadin

Microbial bioconversion studies conducted on the diterpene psiadin have rev ealed that it was metabolized by Aspergillus niger (NRRL 2295) to give 2 al pha -hydroxydeoxopsiadin, Cunninghamella blakesleeana (ATCC 8688a) to give 11 beta -hydroxypsiadin, and Cylindrocephalum aureum (ATCC 12720), Gongrone lla butleri (ATCC 22822), Kloeckera africana (ATCC 20111), and Kluyveromyce s marxianus var, lactis (ATCC 2628) to yield 7 alpha -hydroxypsiadin. Their structures have been established on the basis of spectral data. The struct ure and relative stereochemistry of 7 alpha -hydroxypsiadin was confirmed b y single-crystal X-ray analysis.