ON METABOLISM OF 16ALPHA-HYDROXY-C-21-STEROIDS .I. MICROBIOLOBICAL SYNTHESIS OF RADIOISOTOPICALLY LABELED 16ALPHA-HYDROXYLATED STEROIDS IN HIGH SPECIFIC ACTIVITY

16α-Hydroxyprogesterone-4-14C and 16α-hydroxypregnenolone-7α-3H were obtained in good yields by microbiological hydroxylation of correspondingly labeled progesterone (21.7 mC/mM) and pregnenolone (1.2 C/mM) by Streptomyces roseochromogenus (ATCC 3347). The 16α-hydroxylase was induced with an unlabeled steroid. Then a trace amount of the labeled precursor was incubated, and the products were chromatographically separated, identified and their radiochemical purity established by isotopic dilution analysis. Since a steroid different from the labeled precursor was used as the inducer, the specific activities of the products are presumed to be the same as those of their precursors. The microbiological preparation of labeled steroid compounds in trace quantities can be generally applied to obtain other presently unavailable labeled steroids having high specific activities. © 1968.