Studies in the biotransformation of cortisol to cortoic acids in man. III. 21-Oxidation of 4-14C,21-3H-desoxycorticosterone.

The metabolism of (4-14C, 21-3H) desoxycorticosterone (DOC) in man has been studied. DOC, like cortisol, undergoes oxidation at C-21 with the formation of acidic metabolites (2.3-8.2% of the dose). The release of 3H into the body water, either by oxidation or exchange, is approximately twice as great as the actual formation of acidic metabolites (as judged from the recovery of 14C in the urinary acidic fraction), but both parameters were considerably smaller than the corresponding values for cortisol. The principal metabolite isolated from the urine was 21-hydroxypregnanolone, which had an isotope ratio (3H/14C) greater than that of the dose; the pregnanetriols, which were formed in lesser amounts, had significantly lower isotope ratios than the dose. The absence of the 17-hydroxy group in DOC appears to modify C-21 oxidation, decreasing its magnitude and altering the character of the products.