Studying Of Extraction And Separation And Purification Process For Astragaloside Ⅳ

Purpose: Simplify preparation process of astragalosideⅣto apply to industrial production.Method: Studing the determination conditions of AstragalosideⅣcontent by HPLC-ELSD; After alkaline treatment Radix Astragali, we extracted the astragalosideⅣfrom it by orthogonal experiment with different methods such as water extraction (time, temperature, extraction times), reflux extraction (ethanol concentration, alkaline, boiling time, extraction times) and ultrasonic extraction (extraction temperature, extraction times, Alkaline) to investigate various factors on the extraction rate of astragalosideⅣeffects. Different types of macroporous adsorptive resins (HPD100, HPD300, HPD700, AB-8, D-101), different Astragaloside IV isolation processes (ethanol concentration, elution dose, speed) and different methods (crystallization, washing) were uesd to separated and purified astragalosideⅣ. Qualitative analysis were carried out by TLC, HPLC, UV, IR methods.Result: Finding suitble conditions for determinating Astragaloside IV content by HPLC- ELSD;Radix Astragali were soaked 4 hours by 75% alkaline ethanol (NaOH adjusted pH11) 3 times in order to promote the structural changes from different Astragalosides to astragalosideⅣ( the astragalosideⅣcontent was increased from 0.186% to 0.257%). The concentration of astragalosideⅣ(0.264%), which were treated with 10 times 75% alkaline ethanol (pH11) 2 hours and extracted 2 times by reflux extraction method, were higher than water extraction(0.167%) and ultrasonic extraction (0.165%). The extractives were separated and purified by the column of macroporous adsorptive resins with the conditions of sample concentration (1.8g/L), washing column with 20% ethanol to remove impurities and 70% to purify, 1.5BV/h speed of elution. The isolates were solved by hot methanol (45℃) then concentrated nearly dry. Cold methanol was used to remove the impurities and repeated purification twice. The yield of astragalosideⅣwas 0.25%(98% purity), and the loss rate of washing (3.8%) was lower than crystallization method (13.92%). After TLC, HPLC, UV, IR detection, It's perfect that purificating AstragalosideⅣby methanol washing.Conclusion: Conversion rate (27.63%) from astragalosides to astragalosideⅣwas improved by alkaline treatment. The astragalosideⅣextraction rate(0.264%) was high by the reflux extraction method. The optimization processes such as separation by D-101 macroporous adsorptive resins and purification by methanol were simple(purity more than 97.8%, loss rate lower than 7.14%) , and reduced polysaccharides, flavonoids, proteins and other impurities interference for astragalosideⅣpreparation which provide a basis for industrial production.