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Application of Supercritical Fluid Extraction in Drug Extraction

Supercritical CO2 extraction system

Supercritical Fluid Extraction (SFE) is a high-pressure, high-density supercritical fluid as extractant, which extracts effective components from liquid or solid to improve boiling point or thermal sensitivity, in order to achieve the purpose of separation and purification. In supercritical fluid extraction (SFE), the extractant is a supercritical fluid. It not only has the common characteristics of some gases and liquids, but also has strong solubility. It is more efficient than ordinary liquid-liquid extraction. Nowadays, supercritical fluid extraction (SFE) is widely used in medicine, food, chemical industry, energy, environment and other fields because of its safety and low cost. Supercritical fluid extraction (SFE) is an ideal separation method in drug extraction. It can retain almost all the effective components of natural drugs, such as flavonoids, alkaloids, coumarins, volatile oils and polysaccharides, and plays an irreplaceable role in drug extraction.

Supercritical fluid Extraction Machine
Supercritical fluid Extraction Machine

Supercritical fluid extraction of five drugs:

1. Extraction of Flavonoids

Flavonoids can relax vascular smooth muscle and protect blood vessels. The method of pain extraction is alcohol extraction, alkaline water, hot water, alkaline alcohol and so on, and then separated according to their physical and chemical properties. This method is not only complicated in separation process, but also inefficient in extraction. Compared with the conventional ethanol extraction technology, supercritical fluid extraction was used to extract flavonoids. Ethanol was extracted by 10 times 21 mol/L ethanol reflux for 3 times, 2 hours each time. In SFE technology, CO2 was selected as the extraction medium, and the extraction time was 1 ~ 2 h at 30 ~50 ~C. The optimum extraction conditions of total flavonoids from Dragon's blood with supercritical fluid CO2 fluid were optimized by orthogonal test. Wang Jihao et al. optimized the extraction pressure of 20 MPa, extraction temperature of 35 C and extraction time of 60 min.  

2. Extraction of alkaloids

Compared with the traditional methods, the supercritical fluid technology is simpler, more economical and environmentally friendly than the solvent method and steam distillation method for the extraction of alkaloids. In the extraction of alkaloids from traditional Chinese medicine, because of the great polarity of alkaloids, the solubility of alkaloids in fluids can not be changed by simply increasing the pressure of extraction. Therefore, Cui's efficiency can be improved by adding the solubility of Alpine solutes as entrainers. Zhao Songliang et al.Through the comparison of extraction time, pressure first-order temperature equal to ethanol dosage, determined the influence of single variable on alkaloid extraction, and further explored the optimal experimental conditions: extraction pressure 25 MPa, extraction temperature 60 C, extraction time 3 hours, ethanol dosage 200 ml, alkaloid extraction rate 0.192%.  

3.Coumarin

Coumarin is generally a low polar substance, which is usually extracted by solvent method and acid-base method. Coumarin can be extracted directly by supercritical fluid extraction (SFE). Yan Youshao et al. On the basis of single factor analysis of extraction pressure, extraction temperature, extraction time, analytical pressure and analysis temperature, the main influencing factors were found out by Placktt-Burman experiment, and the important factors were optimized by Box-Behnken impact analysis method. The optimum extraction process of coumarin was obtained. Chen Na studied the supercritical fluid extractor of coumarin in luteolin. The factors affecting extraction from high to low are extraction pressure, extraction temperature and extraction time.  

4. Volatile oils

The main painful extraction method of volatile oils is steam distillation, but the traditional method can make some important boiling points low, and the more oxidizable substances deteriorate during extraction, which leads to inefficiency. Supercritical fluid extraction undoubtedly solves this problem. The volatile oil from Perilla frutescens leaves was extracted by supercritical fluid extraction and analyzed by GC-MS. Jin Jianzhong et al.  found that the extraction pressure of 20 MPa and extraction temperature of 35 ~C for 150 min were the best, and the volatilization rate was only 3.2%. Xiao Xinyu et al. optimized the supercritical extraction process of volatile oil from Laos egg flower by orthogonal design, and the yield reached 5.8927%.  

5. Polysaccharides

There are many kinds of plant polysaccharides and different parts in plants. Therefore, many different methods have been adopted in the study of plant polysaccharide bone removal, including solvent method, acid-base method, enzymatic hydrolysis, ultrafiltration method, microwave method and so on. Compared with supercritical fluid extraction, the single traditional method still has obvious shortcomings. Sheng Guihua et al. extracted polysaccharides from Platycodon grandiflorum by SFE. The optimum extraction pressure was 23.9 MPa, the extraction temperature was 47.9 C, and the carrier ethanol concentration was 58.6%. It has important reference significance for the extraction of Polysaccharides from Platycodon grandiflorum.  

The extraction of active ingredients from medicinal plants began in the past five or six years.

According to the research and development practice, the application of supercritical fluid extraction technology in the extraction and separation of traditional Chinese medicine and modernization of traditional Chinese medicine has great potential and prospects.