MICROBIAL TRANSFORMATION OF STEROIDS - CONTRIBUTION TO 14-ALPHA-HYDROXYLATIONS

The regioselective and stereoselective hydroxylation of steroids by fu ngal strains previously known for their hydroxylation capabilities, su ch as Thamnostylum (= Helicostylum) piriforme ATCC 8992, Mucor griseoc yanus ATCC 1207a, Actinomucor elegans (= Mucor parasiticus) MMP 3122 ( Mucorales), and Zygodesmus sp. ATCC 14716, was investigated with speci al interest for the 14 alpha-hydroxylation reaction. A preliminary scr eening had shown that some of these microorganisms were adequate for t he production of 14 alpha-hydroxylated derivatives of the following st eroids: progesterone, 5 beta-pregnane-3,20-dione, 3 beta-hydroxy-5 bet a-pregnane-20-one, 3 beta-hydroxy- 5 beta-17(alpha H)-etianic acid met hyl ester, androst-4-ene-3, 17-dione, and testosterone. About 20 metab olites have been isolated and purified by silicagel chromatography and semi-preparative reverse-phase HPLC. These metabolites have been full y characterized by H-1, C-13 NMR and mass spectrometry. All the identi fied metabolites were hydroxylated at some distinct positions, such as 6 beta-, 7 alpha-, 9 alpha-, 14 alpha-, 15 beta-, or dihydroxylated a t 6 beta, 14 alpha-, 7 alpha,14 alpha-, 9 alpha,14 alpha-, 14 alpha, 1 5 alpha-, 14 alpha,15 beta-positions; nine of these metabolites have n ot been reported previously. The relationship between the structural f eatures of the investigated steroids and the site-specific hydroxylati on has been delineated, and progesterone was found to be the best subs trate for the production of 14 alpha-hydroxylated derivative, using T. piriforme.