Efficient hydroxylation of functionalized steroids by Colletotrichum lini ST-1

Biotransformation of a series of steroid compounds (estradiol, estrone, androst-4-en-3,17-dione, testosterone, canrenone, 16 alpha,17 alpha-epoxyprogesterone and progesterone) with Colletotrichum lini ST-1 as biocatalyst was investigated. With the exception of estradiol, estrone and progesterone, the microorganism could selectively hydroxylate steroid substrates (4 g/L) with 70-85% conversion rate and 60-76% total products yield. The different hydroxylation sites between androst-4-en-3,17-dione (3) and testosterone (4) suggested that the hydroxyl group or carbonyl group on the substrate at C17 had profound influence on the location of introduced hydroxyl groups. Transformations of 3-ketosteroid (3, 4, 5, 6 and 7) included monohydroxylation or dihydroxylation at 11 alpha and 15 alpha positions, while hydroxylations of 3-hydroxy-steroid (DHEA) were hydroxylation at 7 alpha and 15 alpha positions. Moreover, time course experiments demonstrated dihydroxylation of androst-4-en-3,17-dione (3), canrenone (5) and 16 alpha,17 alpha-epoxyprogesterone (6) were all initiated by hydroxylation on ring-D (C15) followed by attack on ring-C (C11). In this study, several new hydroxylation products were discovered, including 11 alpha,15 alpha-dihydroxyandrost-4-en-3,17-dione (9), 11 alpha,15 alpha-dihydroxy-canrenone (12) and 11 alpha,15 alpha-dihydroxy-16 alpha,17 alpha-epoxyprogesterone (14). The breadth of substrate spectrum and the excellent conversion rates achieved with this fungus indicated that C lini ST-1 was a potential microorganism for production of valuable pharmaceutical ingredients and precursors. (C) 2015 Elsevier B.V. All rights reserved.