Biotransformation of 3-keto-androstanes by Gongronella butleri VKM F-1033

The activity of Gongronella butleri VKM F-1033 towards androst-4-ene-3,17-dione (AD), androsta-1,4-diene-3,17-dione (ADD) and 9α-hydroxyandrost-4-ene-3,17-dione (9α-OH-AD) was studied. Bioconversion products were purified by column chromatography and preparative TLC, and identified by HPLC, mass-spectrometry and 1H NMR spectroscopy.The 7α-hydroxy-AD and 14α-hydroxy-AD were revealed as major products from AD, while 7β-, 6α-, 6β-hydroxylated AD derivatives were observed in small amounts. The presence of 1(2)-double bond in ADD molecule resulted in the accumulation of 14α-, 6β- and 7β-hydroxylated ADD derivatives, whereas no 7α-hydroxy steroid was formed from ADD. Along with hydroxylation, 17-ketone reduction was observed during AD and ADD bioconversion. Unlike other fungal biocatalysts, the strain carried out neither 1(2)-dehydrogenation of AD, nor 1(2)-hydrogenation of ADD. During incubation with 9α-OH-AD, two products, 9α, 14α-dihydroxy-AD and 6β, 9α-dihydroxy-AD were revealed. The results demonstrate the dependence of hydroxylation position on the structure of steroid nucleus.