Screening For Strains Capable Of Hydroxylating Steroids And Characterization Of Products

Biotransformation of steroids plays a critical role in the production of steroid drugs. As a result of increasing demand of steroid drugs, the discovery of novel steroid compounds and the screening of strains with steroid transformation activities are desirable. This research focused on screening of700filamentous fungi for novel steroid hydroxylation activities and characterization of their products. The results are as follows:Screening has resulted in the identification of three strains with hydroxylation activities. Morphological characteristics and the phylogenetic analysis of18S rDNA identified them as Penicillium decumbens, Penicillium oxalicum and Rhizopus oryzae.The products were separated by silica gel column chromatography. The purified metabolites were crystallized in appropriate solvents and then identified by single crystal X-ray diffraction. The results showed that:microbial transformation of16,17α-epoxyprogesterone afforded7β-hydroxy-16a,17a-epoxyprogesterone and7β,11α-dihydroxy-16a,17a-epoxyprogesterone. Transformation of19-nor-4-androstene-3,17-dione generated1α-hydroxy-19-nor-4-androstene-3,17-dione and1β,15a-di hydroxy-19-nor-4-androstene-3,17-dione. Transformation of13β-ethyl-4-gonene-3,17-dione obtained1α-hydroxy-13β-ethyl-4-gonene-3,17-dione,6β-hydroxyl-13β-ethyl-4-gonene-3,17-dione and10β-hydroxy-13β-ethyl-4-gonene-3,17-dione. And the incubation of culture with androst-4-ene-3,17-dione resulted in the isolation of compounds11α-androst-4-ene-3,17-dione.Eight different hydroxylation products were identified, of which compounds6β-hydroxyl-13β-ethyl-4-gonene-3,17-dione,10β-hydroxy-13β-ethyl-4-gonene-3,17-dione and androst-4-ene-3,17-dione were previously reported and the other five metabolic products are novel derivers.