Study On Biotransformation Of Diosgenin By Cototiolus Versicolor

Diosgenin is an important steroidal sapogenins, since it is the main start material to synthesize steroidal drugs, which posess many biological activities, such as antitumor, anti-inflammatory, hypolipemic and so on. In recent years, diosgenin was modifyed to develop new steroidal lead-structure.Microbial transformation is a powerful tool for structural modification of compounds. By specific binding of microbial enzyme to the substrate, the substrate can be catalyzed a series of reactions. In a different way from chemical synthesis, microbial transformation is characteristic of zero-pollution, low-cost, simple operation and mild conditions. At the same time, some multistep reactions always can be completed by microbial transformation through one-step. More importantly, microbial transformation can also complete the reaction of some specific sites which are difficult to be achieved by the chemical synthesis.In this thesis, diosgenin were modified by microbial transformation to develop new bioactive derivatives. The main contents and results are concluded as follow:(1) Screening experiments22 fungi were screened. Cotiolus versicolo, Cunninghamella blakesleeana and Cunninghamella echinulata have the bility to transformate the diosgenin, And the best one for biotransformation was Contiolus versicolor .(2) Isolation and identification of bioconversion products derived from biotransformation of diosgenin by Contiolus versicolorAfter liquid fermentation in a large scale, the broth was extracted with EtOAc, and after separation ,five bioconversion products(from 1 to 5)were isolated from the liquid broth. Then identified the prodeucts by spectroscopic methods, such as IR, MS, 1H-NMR, 13C-NMR, H1-H1COSY, HSQC, HMBC, NOESY. Finally we identified as (25R)-spirost-5-ene-3β,7α,12β,21-tetraol(1),(25R)-spirost-5-ene-3β,7β,11α,21-tetraol(2),.(25R)-spirost-5-ene-3β,7β,12β-tri-ol(3),(25R)-spirost-5-ene-3β,7α,15β,21-tetraol(4),(25R)-spirost-5-ene-3β,7β,12β,21-tetraol(5). The compounds 1 and 2 are new compounds, the other three are known compounds.