Microbial Transformation Of A C₂₇ Steroid Compound By Endophyte From Dioscorea Zingiberensis C.H. Wright

Dioscorea zingiberensis C.H. Wright is a kind of perennial medicinal plants and containslots of diosgenin, which is important in the synthesis of various steroid hormone drugs. Theside chain degradation to diosgenin can generate a serious of C₂₁steroid compounds whichcan be structural modified to get more functional steroid hormone drugs. Nowadays peopleare using microbial transformation to do the structural modification because it’s much betterthan the traditional chemical synthesis. The unique existed enzyme systems inmicroorganisms can not only afford a lot of specific transformation reactions efficiently butalso has plenty advantages such as lower costs, lower pollution and mild reaction conditions.Since1980s, many developed countries start using microbial transformation to accomplish theside chain degradation of diosgenin to get pharmaceutical intermediates.In this research we inherit our group’s former research result about diosgenin’s microbialtransformation and we choose Dioscorea zingiberensis C.H. Wright as the original plantmaterial to isolate endophytes. And then we use those endophytes with another four fungiwhich have been reported having the ability to transform diosgenin together as test strains totest their ability to transform the substrate C27steroid compound. Test results show thatDioscorea zingeberensis C.H. Wright endophyte DZ-34has the best effect. So we use DZ-34as the transformation system to finish the large scale fermentation. After the flitering,separating and EtOAc extrating we get the transformation compounds extracts. By means ofSephadex LH-20, RP-18ODS flash preparative chromatography and column chromatographywe finally get6bioconvertion products. After the structural identification by MS,¹H-NMR,¹³C-NMR, H1-H1COSY, HMQC and HMBC we confirm the structure of2compounds （4and6） and they together with the substrate C27steroid compound are all unreported.Bioconvertion products （4and6） both have an oxygen bridge between C-7and C-16andC-16become a hemiketal carbon. In addition there is a hydroxylation happened to C-14 （Compound6）.