Preparation Of Ginsenosides 25-OH-Rg2 Group

In this paper,the Re,and an unknown saponin were transformed into 20?S,R?-Rg2and20?S,R?-25-OH-Rg2 by using FeCl₃ as catalyst under the organic alcohol system.Using ginsenoside Re as substrate FeCl₃ as catalyst,the organic alcohol system,alcohol concentration and Fe³⁺concentration,reaction temperature,reaction time and substrate concentration were optimized respectively.The optimum conditions for Fe³⁺to catalyze re saponins in glycerol system are as follows:concentration of propanol 50%?V/V?,iron ion concentration 0.35 mol/L,substrate reaction concentration 1.2%,reaction time 26 h at50?,ethanol concentration 20%?V/V?,reaction concentration of iron ion 0.8 mol/L,reaction of substrate The concentration was 0.7%and the reaction time was 17 h at 50?.Under the optimum reaction conditions,the yields of 20 g Re at 50%?V/V?propanol and 20%?V/V?were 65%?W/W?and 63?W/W?,respectively.The 13 g product was desacked by AB-8 macroporous resin,and the product was 10.52 g,and the yield was 75%?W/W?The5 g desugar product was separated by silica gel column chromatography,and a pure 2 g mixture of 20?S,R?-25-OH-Rg2 was obtained in 40%?W/W?yield.