How to extract traditional Chinese medicine

There are many extraction methods of traditional Chinese medicine, the most important one is solvent extraction.

Traditional Chinese medicine components are extracted by solvent methods, such as impregnation, percolation, decocting method, reflux extraction and continuous extraction. At the same time, the crushing degree of raw materials, extraction time, extraction temperature, equipment conditions and other factors will also affect the extraction efficiency and must be considered.

1. Dipping method: Dipping method is to soak the treated medicinal materials in an appropriate solvent at normal temperature or warm temperature (60 ~ 80℃) to dissolve the components. This method is suitable for extracting effective components which are easily damaged by heat and contain a lot of starch, gum, pectin and mucus. Simple and easy to operate, but the leaching rate is poor, especially when water is used as solvent, its extract is easy to mildew and deteriorate, so it is necessary to pay attention to adding appropriate preservatives.

2. Percolation method: Percolation method is to put Chinese herbal medicine powder into a percolator, and constantly add new solvent to make it penetrate into the medicinal materials, so that it can be considered that the extraction is basically complete. In mass production, the collected dilute osmotic solution is often used as a solvent for another batch of new raw materials. This method has high leaching efficiency and clear leachate, but it consumes a lot of solvent, takes a long time and is still troublesome to operate.

3. decocting method: decocting method is the earliest traditional leaching method used in China. The containers used are generally pottery, casserole or copper enamel utensils, and it is not advisable to use an iron pan to avoid discoloration of the liquid medicine. It is best to stir frequently when heating with direct fire, so as to avoid local medicinal materials being heated too high and easily scalded. In pharmaceutical factories with steam heating equipment, large reaction tanks, large copper pots, large wooden barrels or cement pools are often heated by steam. Several boilers can also be connected with each other through pipes to continuously fry bubbles. This method is simple, and most of the components in the medicine can be extracted to varying degrees, but it is not suitable for traditional Chinese medicine with volatile components and effective components that are easily damaged by heat. Traditional Chinese medicine containing polysaccharides is viscous after decoction and difficult to filter.

4. Reflux extraction method: organic solvent is used for heating extraction, and reflux heating device is needed to avoid solvent volatilization loss. For small-scale operation, a reflux condenser can be connected to a round bottom flask. Soak the solvent on the surface of medicinal materials for about 1 ~ 2 cm. Heating and refluxing in a water bath, generally keeping boiling for about 65438+/-0 hours, cooling and filtering, and then adding solvent to the residue for the second and third heating, and refluxing for about half an hour respectively, or until the effective components are basically extracted. The extraction efficiency of this method is higher than that of cold soaking method, and continuous extraction method is often used in large-scale production. However, this method is not suitable for parts that are easily damaged by heat, and the solvent consumption is still large and the operation is troublesome.

5. Continuous extraction method: In order to make up for the shortage of large solvent consumption and troublesome operation of reflux extraction method, continuous extraction method can be used. Fat extractors or Soxhlet extractors are usually used in laboratories.

Using volatile organic solvents to extract the effective components of Chinese herbal medicines, whether in small-scale experiments or large-scale production, the continuous extraction effect is better, the amount of solvent required is less, and the extracted components are more complete. Continuous extraction usually takes several hours to extract completely. The extracted components are heated for a long time, so this method is not suitable for components that are unstable and changeable when heated.

The above traditional methods for extracting traditional Chinese medicines have the following disadvantages:

(1) decocting method lost more effective components, especially water-insoluble components;

(2) In the extraction process, the organic solvent may interact with the effective components, making them lose their original utility;

(3) Ineffective components cannot be removed to the maximum extent, and the concentration rate is not high enough;

(4) In addition to the effective components, there are often many impurities and a small amount of fat-soluble components in the extract, which is not conducive to refining;

(5) High temperature operation will lead to a large number of decomposition of heat-sensitive effective components.