Efficient hydroxylation of functionalized steroids by Colletotrichum lini ST-1

Abstract Biotransformation of a series of steroid compounds (estradiol, estrone, androst-4-en-3,17-dione, testosterone, canrenone, 16α,17α-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-keto-steroid ( 3 , 4 , 5 , 6 and 7 ) included monohydroxylation or dihydroxylation at 11α and 15α positions, while hydroxylations of 3-hydroxy-steroid (DHEA) were hydroxylation at 7α and 15α positions. Moreover, time course experiments demonstrated dihydroxylation of androst-4-en-3,17-dione ( 3 ), canrenone ( 5 ) and 16α,17α-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 11α,15α-dihydroxyandrost-4-en-3,17-dione ( 9 ), 11α,15α-dihydroxy-canrenone ( 12 ) and 11α,15α-dihydroxy-16α,17α-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.