Enzymatic Degradation of Side-Chain of Adrenocortical Steroids: Conversion of Hydrocortisone to Reichstein's E.

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Abstract
Previous demonstration that the microsome and supernatant fractions of rat liver homogenates contain an enzyme which catalyzes the reduction of the C-20 ketone group of adreno-cortical steroids, was confirmed. The microsome fraction also contains an enzyme system which catalyzes the reduction of the [DELTA] 4-3-ketone group. Both systems require reduced pyridine nucleotide, and were inhibited by the p-chloromercuribenzoate (PCMB). However, glucose-6-phosphate, added as an auxiliary means of TPNH generation, was also inhibited by PCMB. The microsome fraction was shown to catalyze the reduction of the 17-keto group of C-19 steroids in the presence of the glucose-6-phosphate dehydrogenase system. A large scale incubation of hydrocortisone with rat liver microsomes was extracted and processed chromatographically. Reichstein''s substance E was obtained in high yield as a product of the reaction. Another product chromatographically similar to Reichstein''s E, but without absorption at 240 [mu], was obtained but not further characterized.