Introduction to the principle, characteristics and application of ultrasonic extraction

Introduction to the principle, characteristics and application of ultrasonic extraction

Ultrasound refers to sound waves with frequencies above 20 kHz, out of  the human hearing range.

Ultrasonic extraction has been widely used in the quality testing of traditional Chinese medicine preparations (drug inspection system). In the Pharmacopoeia of the People's Republic of China, there are 232 varieties of ultrasonic treatment, and there is a growing trend.

In recent years, the application of ultrasonic technology in the extraction process of traditional Chinese medicine preparations has received more and more attention. Ultrasonic technology is a very effective method and means for the extraction of active ingredients from natural products. As a new technology for the preparation of traditional Chinese medicine preparations, ultrasonic extraction has broad prospects.

Ultrasonic extraction utilizes the mechanical effects, cavitation effects and thermal effects of ultrasonic waves to extract biological active components by increasing the velocity of the medium molecules and increasing the penetrating power of the medium.

1, the principle of extraction

(1) Mechanical effect The propagation of ultrasonic waves in the medium can cause the medium particles to vibrate in their propagation space, thereby strengthening the diffusion and propagation of the medium, which is the mechanical effect of ultrasonic waves. Ultrasonic waves generate a kind of radiation pressure in the process of propagation, which propagates along the direction of sound waves, which has a strong destructive effect on the material, which can deform the cell tissue and denature the plant protein. At the same time, it can also give the medium and the suspension different accelerations. And the velocity of the medium molecules is much faster than the velocity of the suspension molecules. Thereby, friction is generated between the two, which can depolymerize the biomolecules, so that the active components on the cell wall dissolve in the solvent more quickly.

(2) Cavitation effect Normally, some microbubbles are dissolved more or less inside the medium. These bubbles vibrate under the action of ultrasonic waves. When the sound pressure reaches a certain value, the bubbles increase due to the directed diffusion (rectieddiffvsion). Large, forming a resonant cavity, and then suddenly closing, this is the cavitation effect of the ultrasonic wave. When the bubble is closed, it generates pressure of several thousand atmospheres around it, forming a micro-shock, which can cause the plant cell wall and the whole organism to rupture, and the entire rupture process is completed in an instant, which is favorable for the dissolution of the active ingredient.

(3) Thermal effect Like other physical waves, the propagation of ultrasonic waves in a medium is also an energy propagation and diffusion process. That is, during the propagation of ultrasonic waves, the acoustic energy is continuously absorbed by the particles of the medium, and the medium will absorb it. All or most of the energy is converted into heat energy, which leads to an increase in the temperature of the medium itself and the medicinal tissue, which increases the dissolution rate of the active ingredient of the drug. Since the increase in the internal temperature of the drug tissue caused by the absorption of the acoustic energy is instantaneous, the biological activity of the extracted component can be kept constant.

In addition, ultrasound can also produce many secondary effects, such as emulsification, diffusion, crushing, chemical effects, etc. These effects also promote the dissolution of active ingredients in plants, promote the entry of active ingredients into the medium, and fully mix the medium to accelerate The extraction process is carried out and the extraction rate of the active ingredient of the drug is improved.

2, the characteristics of ultrasonic extraction

(1) No need to heat during ultrasonic extraction, avoiding the adverse effects of traditional Chinese medicine boiling and long-time heating on the active ingredients, suitable for the extraction of heat-sensitive substances; at the same time, because it does not require heating, it also saves Energy.

(2) Ultrasonic extraction improves the extraction rate of active ingredients of the drug, saves raw materials, facilitates the full utilization of traditional Chinese medicine resources, and improves economic benefits.

(3) The solvent is used in a small amount, and the solvent is saved.

(4) Ultrasonic extraction is a physical process in which no chemical reaction occurs during the entire leaching process and does not affect the physiological activity of most of the active ingredients of the drug.

(5) The extract has a high content of active ingredients, which is advantageous for further purification.

3. Application of ultrasonic technology in the extraction of natural products

Compared with the water decoction method, the extraction method of Astragalus by ultrasonic method showed that the extraction time was shortened compared with the conventional decoction method, and the extraction rate of baicalin was increased. Ultrasonic extraction was 10, 20, 40, 60 min. The extraction rate was higher than that extracted by boiling for 3 hours.

Ultrasonic extraction of rutin, the main active ingredient in glutinous rice, showed that the extraction rate of rutin obtained by ultrasonic treatment of glutinous rice for 30min was 47.56% higher than that of hot alkali extraction. Compared with immersion method, ultrasonic extraction was 40min, and rutin was obtained. The rate was 22.53%, while the yield of 48h soaking was only 12.23%. Ultrasonic extraction of glycosides from plants is an effective method to save 30-40% of raw materials.

Alkaloids are extracted from the roots of Rauvolfia, which requires 43 h for conventional impregnation, and 15 min for ultrasonication, and all alkaloids can be raised. The conventional method requires 5 hours to extract alkaloids from the bark of Cinchona, and ultrasonication can be completed for up to 30 minutes. It takes 3 hours to extract the mandala base from the mandala leaf by the conventional method, and only 30 minutes by the ultrasonic method. It takes 3 hours to extract the anthraquinones from rhubarb by decoction, and only 10 minutes by ultrasonic method, and the yield is high.

In short, ultrasonic extraction has the characteristics of time saving, energy saving, material saving and high yield.