The chemical composition of traditional Chinese medicine is very complex. A single traditional Chinese medicine often contains various compounds such as alkaloids, amino acids, organic acids, terpenes, steroids, sugars, etc. The effect of the combination of multiple drugs in a compound recipe is not a simple superposition of chemical components, but also a single drug. The ingredients that work for different diseases are different. Therefore, it is particularly important to study the extraction method of effective parts. Finding an effective and suitable extraction method is the key to identifying the active parts of traditional Chinese medicine, and it is also the key to clarifying the active ingredients of traditional Chinese medicine.
1. Solvent Extraction
The solvent extraction method is a traditional Chinese medicine extraction method. In the process of Chinese medicine extraction and separation, due to the osmotic effect of the solvent, the solvent continuously enters the tissue cells of the medicinal material until the concentration of the solution inside and outside the cell reaches a dynamic balance, so that the effective components of the traditional Chinese medicine are dissolved. Commonly used methods are water extraction, organic solvent extraction, decoction, and continuous extraction. The researchers used distilled water, 70% ethanol, ethyl acetate, n-butanol and other different polar solvents to analyze the active components of Prunella vulgaris, and found that different solvent extracts of Prunella vulgaris had antioxidant activity, of which the effective parts were mainly concentrated in 70%. The ethanol extract has the highest content of total phenols and flavonoids, and the 70% ethanol extract of Prunella vulgaris has higher DPPH·,·OH scavenging activity and liposome peroxidation inhibitory activity, and the distilled water extract of Prunella vulgaris has the highest O2-· scavenging activity. good. The solvent extraction method is affected by the nature of the extraction solvent and the extraction times, temperature, pressure, time, etc., and has the disadvantages of a long extraction cycle, large solvent consumption, and low purity.
2. Ultrasonic extraction
Ultrasonic extraction technology is one of the new technologies for extracting the active ingredients of traditional Chinese medicine in recent years. It uses the mechanical effect, thermal effect, cavitation effect, etc. produced by ultrasonic radiation of the drug solution to instantly destroy the cell wall of the medicinal material, enhance the penetration of the solvent, and then increase the active ingredients of traditional Chinese medicine. Dissolution insolvent has the advantages of a high extraction rate, saving medicinal materials and solvents, and short extraction time, and is suitable for the extraction of most active ingredients. The researchers found that the ultrasonic extraction method can improve the extraction rate and shorten the extraction time, and is suitable for traditional Chinese medicine compounds containing more polysaccharides. Although the ultrasonic extraction method has the characteristics of a high extraction rate, it is closely related to the state, polarity and solubility of the active ingredients of traditional Chinese medicine, and is also affected by parameters such as ultrasonic frequency, power, and time. The appropriate ultrasonic parameters and online measurement technology issues need to be studied.
3.supercritical extraction
The supercritical extraction method uses the characteristics of the fluid in the supercritical state that the viscosity is close to the gas, the density is close to the liquid, and the diffusion coefficient is between the gas and the liquid. The fluid is used as a solvent, and the density of the solute is adjusted by changing the temperature or pressure. It can extract effective parts and has high selectivity for the extraction and separation of different components of traditional Chinese medicine. At present, the commonly used fluid is mostly CO2, which has lower criticality and critical pressure, higher temperature and pressure sensitivity, and is often used in the extraction of active ingredients of traditional Chinese medicine. The researchers screened the volatile oil extraction process of argyi leaves by the CO2 supercritical extraction method and found that the extraction conditions of the effective parts of argyi leaves were the extraction pressure of 20 MPa, the temperature of 30 ℃, the separation pressure of 8 MPa, and the temperature of 55 ℃. 1.443% and the extraction amount of eucalyptol was 0.318 mg/g. Although supercritical fluid extraction has many advantages, it also has limitations in the extraction of traditional Chinese medicine. The supercritical extraction device is expensive and consumes a lot of energy. It often cannot meet the requirements of the purity of active ingredients when used alone, and it is more affected by the polarity and molecular weight of traditional Chinese medicine.
4. Microwave Extraction
Microwave extraction is to use of microwave thermal effects to heat medicinal materials and organic solvents. According to the difference in the structure of different substances and the difference in microwave absorption capacity, the effective components of traditional Chinese medicines can be dissolved to achieve the purpose of extraction. The extraction efficiency is high, the operation is simple and convenient, and it is widely used in Chinese medicine extraction research. Microwave extraction is cleaned, crushed, soaked, microwaved, separated, concentrated, dried, and pulverized to obtain extracts, which are often used to extract effective parts of traditional Chinese medicines such as flavonoids, glycosides, terpenes, organic acids, and alkaloids. The researchers used the single factor experiment method to extract Nuanxin Fang (red ginseng, cooked aconite, coix seed, orange-red) and found that the optimal conditions for microwave extraction of active ingredients were power 1200 W, extraction time 40 min, and extraction times 1 time. Compared with other extraction methods, the microwave extraction process can shorten the extraction time, save material cost, and is beneficial to the extraction of traditional Chinese medicine compounds. However, microwave extraction is only suitable for heat-stable active ingredients. For heat-sensitive substances, microwave heating can cause their denaturation and inactivation. Therefore, factors such as solvent type, extraction time, extraction temperature, water content, and microwave power need to be considered when applying microwave extraction.
5. Macroporous Resin Adsorption Method
Macroporous adsorption resin can selectively adsorb organic compounds in traditional Chinese medicine through surface coefficient, surface electrical property, and formation of hydrogen bonds. It has the characteristics of good selectivity, high stability, fewer interference factors, and can be recycled and reused. It is widely used in the separation of traditional Chinese medicine. Active parts and active ingredients. The researchers used D101 macroporous adsorption resin to separate and purify different solvent extracts of Jiuwei Qiang Huo Tang. The total compound quantity and solid yield were used as purification indicators, and factors such as sample load, concentration and elution concentration were investigated respectively. The results show that the macroporous resin adsorption method is reasonable, stable and feasible to separate and purify the effective parts of Jiuwei Qiang Huo Decoction. The researchers screened the best extraction method of Perrin through antiviral experiments and found that the AB-8 weakly polar macroporous adsorption resin had the best separation and purification effect on Perrin, and the T1 value of the eluted part with a volume fraction of 25% ethanol could reach 127.001. It is the best effective site for Perrin to inhibit intestinal EV-71 virus. However, the adsorption of macroporous resins is selective, the separation effect of water-soluble components is obvious, and the adsorption of sugars and pigments is weak, which has limitations in practical applications.
6. Ultrafiltration Membrane Separation Method
The ultrafiltration membrane separation technology is a high-efficiency, energy-saving, pollution-free separation technology developed in recent years. The researchers conducted a study on the separation of the effective parts of Paeonia lactiflora Paeonia by PVC ultrafiltration membrane and separated the water extract of Paeonia lactiflora through ultrafiltration membranes with different pore sizes. The results showed that the total glucoside content of paeony in the filtrate after ultrafiltration with a large pore size ultrafiltration membrane was significantly higher than that in the original solution.
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