Microbial Transformations of Natural Antitumor Agents: Products of Rotenone and Dihydrorotenone Transformation by Cunninghamella blakesleeana

Various species of Absidia, Aspergillus, Cunninghamella, Trichothecium, Penicillium, and Phanerochaete were found to transform rotenone to one or more metabolites. Two biotransformation products were isolated from a preparative-scale incubation of rotenone with Cunninghamella blakesleeana and identified as 1′,2′-dihydro-1′,2′-dihydroxyrotenone and 3′-hydroxyrotenone (amorphigenin). The catalytic reduction of the isopropylene side chain of rotenone resulted in the formation of 1′,2′-dihydrorotenone. The latter was transformed by C. blakesleeana to 2′-hydroxy-1′,2′-dihydrorotenone.