Extraction And Chemical Synthesis Of Salidroside In Rhodiola

Rhodiola has been recorded in the Compendium of Materia Medica as a classy traditional Chinese medicine to be beneficial to human beings.Researchers have studied salidroside comprehensively and systematically.The results showed that salidroside could alleviate hypoxia in the oxygen-poor environment,prevent exposure of strong ultraviolet radiation,relieve body fatigue,remove free radicals,and regulate immune system,etc.Salidroside extracted from the Rhodiola was made into health food and was sold on the market.What's more,research on the application of salidroside monomer as the main component of the heart rescue drugs has come to the clinical stage,which will dramatically increase the need of Rhodiola of high purity.Currently,the large-scale application of salidroside preparation technology cannot be applied whether by natural extraction methods or through biological and chemical synthesis.Therefore,research on the extraction and chemical synthesis of salidroside was carried out in order to develop a salidroside preparation method which could be applied to industrial production.There were mainly three parts in this paper:(1)Extraction of salidroside from Rhodiola rosea;(2)Chemical synthesis of salidroside;(3)Structure characterization and performance determination of salidroside.Specific work and achievements were as follows:(1)Rhodiola powder was used as raw material and ethanol was used as solvent.Ultrasonic-assisted heat reflux method was used to extract salidroside and the content of salidroside was determined by HPLC.The optimal extraction conditions were as follows:the volume fraction of ethanol was 70%,the solid liquid ratio was 1:15 g/mL and the temperature was 61?.Under this circumstance,the extraction rate of salidroside was 1.9%.(2)In this paper,the salidroside was synthesized by chemical method.The first step was the reaction of tyrosol(hereinafter referred to as TYR)and acylation reagent,which produced 2-(4-benzoylphenyl)ethanol(hereinafter referred to as BE).In this step,the effect of acyl protecting group,feed ratio and reaction time on BE yield was studied.The optimum conditions were as follows:feed ratio of 1:1.5,reaction time of 4 h,yield of 90%,purity of 98%.The second step was the synthesis of 1-[2-(4-benzoylphenyl)-ethyl]-?-D-2,3,4,6-0-tetra-acetylglucopyranoside(hereinafter referred to as BETA)using BE and penta-O-acetyl-?-D-glucose(hereinafter abbreviated as PAG).In this step,the effect of catalyst,feed ratio and reaction time on the yield of BETA was studied.The optimum conditions were as follows:ZnCl2 as catalyst,feed ratio of 1:2,and reaction time of 30 min.At last,the yield was 47%and the purity was 95%.The third step was to use BETA as raw material to deprotect the reaction of CH3ONa/CH3OH so as to synthesize salidroside.In this step,the effect of pH value and reaction time on the yield of salidroside was studied.The optimum conditions were as follows:pH value of 11,and reaction time of 1 h.The yield was of 82%and the purity was 95%.(3)The structures of the synthesized products were characterized by IR and 1HNMR.The properties of the products were characterized by melting point,TLC,SEM and HPLC.The results were in agreement with the literature.