Microbial Preparation Of Diosgenin And Its Antioxidant Activity In Vitro

The production of diosgenin by acid hydrolysis has done much harm to the enviroment and the microorganism conversion technology is still in laboratory research stage, so continuing to find the high efficient microbial strains remains important significance to the industrial production of diosgenin. Dioscorea Zingiberensis C.H.Wright(DZW) is one kind of the Dioscorea plants, which has the world’s highest content of diosgenin. And this paper took the DZW as raw material, the microwave-assisted extraction technology of total steroid saponins was studied, there kinds of microorganisms which can transform the total steroid saponins to diosgenins effectively were found out and at the end the antioxidant activity of diosgenin in vitro were studied for the first time. Through the research, this thesis had drawn the following conclusion:The study on the process of total steroid saponins extracted with microwave. By HPLC, LC-MS/ESI+ and TLC, the best acid hydrolysis of total saponins was identified as 2mol/L sulfuric acid and 3h hydrolysis time, its content can be determined more accurately under these conditions. The optimal extracting conditions were established as 75% ethanol as solvent, ratio of solid/liquid 1:20(g/m L), temperature 75℃, irradiation power 600 W and three extraction cycles of 6 min each. Scanning electron microscopy(SEM) images of DZW processed by four different extractions provided visual evidence of the disruption effect on DZW.The study on preparation of diosgenin by microbial fermentaion. By screening and fermention, three strains of microorganisms were found that can transform total steroid saponins to diosgenin. Taking Aspergillus awamori and No.2.20140425 as associate strains to ferment total steroid saponins, the conversion rate can be increase greatly. Throuhg orthogonal test and verifying test, The optimal fermentation conditions were established as addition of carbon source 1.5%, addition of nitrogen source 1%, p H 6, inoculum size 6%, fermentation temperature 30℃, fermentation time 6d. In this condition, the conversion rate can reach about 71.57%. At the end, 98.5%(178.10mg/180.88mg) diosgenins in fermented production were separation and purfication by SGCC. HPLC determention result showed that its purity reached 96.5%.The study on vitro antioxidant activtiy of diosgenin. Based on the scavenging assays of DPPH radical, hydroxyl radical, superoxide anion radical and the comparison of those of Vc, we found out that disogenin has ideal scavenging effect on DPPH radical and superoxide anion radical but it has little effect on hydroxyl radical. All in all, these results showed that diosgenin has a certain antioxidant activity. By cell antioxidant activity assay, we confirm that diosgenin shows a certain degree of antioxidant activity.