Stereochemistry of Hydrogenation of (—)-Dehydrogriseofulvin to (+)-Griseofulvin with a Cell-Free System of Streptomyces cinereocrocatus

To elucidate the stereochemistry of the hydrogenation of(-)-dehydrogriseofulvin (la) to (+)- (3a) by Streptomyces cinereocrocatus, we have prepared from the microorganism a cell- system which can transform la to 3a. The hydrogenation activity of the cell-free system increased in the presence of added reduced nicotinamide adenine dinucleotide phosphate (NADPH). The stereochemistry of hydrogenation was determined by 400 MHz proton nuclear magnetic resonance (¹H-NMR) analysis of the products obtained by the enzymatic conversion of (—)-[5^/-²H]-dehydrogriseofulvin (lb) and also by the enzymatic conversion of h in medium containing deuterium oxide.