Steroid transformations microbial oxidations

Fig. 2. Oxidation and reduction reactions using microbial transformation for steroid synthesis.

Microbial and enzymic transformations of steroids have been reviewed. 5a-Pregnane-7,20-dione gave a reasonable yield of the la, 12/3-dihydroxy-derivative on incubation with Calonectria decora High yields of 10 8-hydroxy-19-nortes-tosterone were obtained by incubation of 19-nortestosterone with Rhizopus arr-hizus (Fischer 11). Oxidation of canrenone with a Penicillium species provided the 15a-hydroxy-derivative (348) which is a product of human metabolism of spironolactone.16j8-Hydroxylation of androstenolone, androst-4-ene-3,17-... 

Oxidations - Enzymes which functionalize inactivated carbon are often difficult to obtain and handle. Many examples exist of oxidations using microbial fermentations, e.g. for steroids, and recently in olefin oxidation.Such preparative transformations have not been achieved with purified enzymes and are unlikely to be amenable to large-scale in vitro approaches because of instability and complexity of the enzyme systems. Klibanov and coworkers, however, have developed systems with horseradish peroxidase and xanthine oxidase for oxidation of aromatic alcohols and amines, for use in syntheses and waste water treatment. Hydroxyphenyl compounds can be oxidized to dihydroxy derivatives. L-DOPA has been made from L-tyrosine in this manner.Cyclohexanone was oxidized to t-caprolactone with a bacterial oxygenase. 

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