Optimization Of Extraction And Chemical Synthesis Of Salidroside In Rhodiola

Rhodiola is a traditional Chinese herbal plant.Most ancient books have recorded Rhodiola and its effects.Modern research shows that salidroside,the main component of Rhodiola,has the functions of scavenging free radicals,calming hypnosis,enhancing immunity,anti-tumor,and protecting the cardiovascular and cranial nervous system.Due to its multiple effects on the human body,salidroside has a good application prospect in the fields of food and health care products.A large number of Rhodiola Biscuits,Rhodiola Drinks,and salidroside functional foods have been sold,and the demand for food-grade salidroside has been drastically increased.At present,the extraction method is widely used to obtain salidroside,but this process has the problems of low extraction yield and low product purity.The chemical synthesis of salidroside has the problems of high cost and use of toxic and harmful reagents.In view of these problems,this thesis aims to optimize the extraction and chemical synthesis of salidroside.It is hoped that the extraction and synthesis conditions of salidroside suitable for industrial application can be determined and extended to practical applications.This paper mainly carries out research work from the following three aspects:(1)Optimization of the extraction process of salidroside:Compared with the conventional extraction method,this paper used ultrasonic assisted method to extract salidroside from Rhodiola root.The best factors were determined by response surface testing and the crude product was purified by column chromatography.The experimental results showed that when the extraction solvent was 70%ethanol solution,and the ratio of the liquid to the extraction solvent was 1:19(g:mL),and the pH of the extraction solvent was 8,extraction temperature was 73℃,and the extraction time was 70 min.The extraction yield of salidroside was the highest,which was 2.4%,and the purity was 98%.(2)Optimization of chemical synthesis process of salidroside:This paper uses a chemical method to synthesize salidroside.The first step was to protect the phenolic hydroxyl group by reacting benzoyl chloride with p-hydroxyphenylethanol under tetrabutylammonium bromide as a catalyst to form the hydroxyacylated product 2-(4-benzoyloxyphenyl)ethanol.In this step,we studied the effect of different substrates,feed ratios and reaction times on the synthesis yield of 2-(4-benzoyloxyphenyl)ethanol in this step.The experimental results showed that when the reaction solvent was dichloromethane,and the molar ratio of p-hydroxyphenylethanol to benzoyl chloride was 1:2,and the reaction time was 2.5 h,the synthesis yield was up to 90%and the purity was 97%.The second step was 2-(4-oxygen benzoyl phenyl)ethanol and glucose reaction generated five acetyl 1-[2-(4-oxygen benzoyl phenyl)ethyl]-2,3,4,6-O-four acetyl-β-D-pyran glucoside.In this step,we studied the effects of catalyst addition,differentreaction substrates,the feed ratio and reaction time on the synthesis yield.The experimental results showed that when the molar ratio of BE and ZnC12 added was 1:2.75,and toluene was selected as the reaction solvent,the molar ratio of 2-(4-benzoyloxyphenyl)ethanol to pentaacetylglucose was 1:1.5,and the reaction time was 25 min,the synthesis yield was 53%,and the purity was 95%.The third step was to protect the synthetic salidroside.In this step,we studied the effect of the pH of the reaction solvent,the reaction time,and the crystallization solvent on the synthesis yield.The experimental results showed that when the pH of the reaction solvent was 11,the reaction time was 2 h,and the crystallization solvent was 80%ethanol,the synthesis yield was 90%;the purity was 97%.(3)The structure of the synthesized product was determined by nuclear magnetic resonance spectroscopy,infrared spectroscopy,thin layer chromatography,melting point,scanning electron microscopy and high performance liquid chromatography.The results showed that the final composition was the desired salidroside.