On the relative conversion of 6,7-3H-estrone to 3H-15α-hydroxyestrogens and 3H-7α-hydroxyestrogens by Glomerella fusarioides

Mixtures of 6, 7‐3 H‐estrone and 16‐14C‐estrone were fermented in media of Glomerella fusarioides. Conversions of each form of estrone to 15α‐hydroxyestrone (15α‐OHE1) and 7α‐hydroxyestrone (7α‐OHE1) and in one experiment to 15α‐hydroxyestradiol (15α‐OHE2) and 7α‐hydroxyestradiol (7α‐OHE2) were compared. The metabolites were separated and purified by repeated column chromatography on Celite. Similar to results reported for non‐isotope studies, 14C‐estrone was converted to more 7α‐hydroxyestrogens than 15α‐hydroxyestrogens. The reverse was true for the tritiated substrate. The difference is attributed to an isotope effect resulting in diminished hydroxylation of the tritiated substrate at C‐7 with concomitant enhanced hydroxylation at C‐15 where no isotope effect would be expected. Reduction to 17β‐hydroxyestrogens also occurred, but quantitative significance for this pathway was confined to the 15α‐hydroxy compound.