Acidic metabolites. V. Isosteroids as intermediates in cortoic acid formation.

The role of steroid-17-aldols, 20 beta-isocortisol (11 beta, 17,20 beta-trihydroxy-3-oxo-pregn-4-en-21-al) or 20 beta-iso THE (3 alpha,17,20 beta-trihydroxy-11-oxo-pregnan-21-al), as preferred intermediates for the biosynthesis of cortoic acids was studied in human subjects. The results demonstrated that the isosteroids were converted moe efficiently than cortisol to cortoic acids and hexahydro neutral metabolites. In all cases, the oxidation state at C-11 was largely conserved. After the administration of the 20 beta compounds both 20 alpha and 20 beta epimers of the acidic and neutral metabolites were isolated. This inversion occurred without oxidation at C-20 and provided evidence for the mediation of an epimerase in this transformation. The results further indicate that reversion of the isosteroids to ketolic intermediates (i.e. cortisol, tetrahydrocortisol, and tetrahydrocortisone did not occur.