Preparation Of Ginsenoside Rh1 Group By Enzymatic And Metal Ion Catalysis And Composition Analysis Of Its Products

The aim of this thesis was to prepare ginsenoside Rh1（including 20（S）-Rh1、20（R）-Rh1、Rk3、Rh4,etc,referred to as Rh1 group）group by catalytic transformation of protopanaxatriol type saponin Re with two-step method of enzymatic conversion and metal ion catalysis.The catalytic reaction conditions in each step were researched,and the products were analyzed then purified.The Absidia sp.P39r strains were selected to produce enzymes,the fermentation c onditions of the enzyme were optimized,and the optimum fermentation conditions wer e determined as follows:ginseng was used as inducer,the amount of inducer was 25%（V/V）and the fermentation time was 6 d;The optimum conditions for the enzymatic reaction of extracting crude enzyme solution hydrolyzing ginsenoside Re to Rg1 were:p H 5.0,reaction temperature 40℃,ethanol concentration 10%（V/V）and substrate co ncentration 12 mg/m L,reaction time 16 h.Rg1 was prepared under the above optimu m conditions.The conversion rate was 70.5%（W/W）and the purity was 99.7%（W/W）.Fe³⁺was chosen as metal ion catalyst,and the optimum conditions for the catalys is of ginsenoside Rg 1 were determined as follows:45%（V/V）ethanol solvent,Fe³⁺c oncentration 1.4 mol/L,reactio n tempera t ure 50℃,substrate concentration 17 mg/m L,reaction time 14 h.Rh1 group mixtures were prepared with ginsenoside Rg1 as substrate under the above optimal Fe³⁺reaction conditions,the conversion rate was 80.2%（W/W）.The content of 20（S）-Rh1,20（R）-Rh1,Rk3 and Rh4 in the Rh1 group mi xtures were 36.38%（W/W）,18.79%（W/W）,5.60%（W/W）and 20.48%（W/W）,respectivel y.An unknown compound（compound 1）in Rh1 group was isolated and purified by liquid chromatography.Compound 1 was identified as 25-trihydroxydammar-6-O-beta-D-glucopyranosyl-20（-H₂O）-20（22）-en-protopanaxatriol by nuclear magnetic resonance（N MR）,named 25-OH-Rh4.