Application of ultrasonic technology in the extraction of chinese herbal medicine components

The ingredients contained in herbal medicine are quite complex, including not only effective ingredients, but also ineffective ingredients. In order to improve the therapeutic effect of Chinese herbal medicine, its effective ingredients must be extracted. Extraction is directly related to the content of effective ingredients in finished products and their internal quality, monitoring efficacy and economic benefits.

At present, the common methods for extracting the effective ingredients of Chinese herbal medicine in actual production include immersion method (normal temperature immersion method, warm immersion method, decoction method), percolation method, reflux method, etc. The extraction time is long and the extraction rate is low. With the development of modern science and technology, ultrasonic technology has been widely used in industry, agriculture, medicine and health and other fields. Because of the advantages of this method, such as simple equipment, convenient operation, short extraction time, high extraction rate, energy saving, medicine saving, and no heating, its application in the extraction of Chinese herbal medicine ingredients has received more and more attention. This paper reviews the application of ultrasonic technology in the extraction of Chinese herbal medicine components and the problems that should be paid attention to in the extraction process.

1. Theoretical basis for ultrasonic extraction of Chinese herbal medicine ingredients:

Ultrasonic is a kind of elastic mechanical vibration filter, which is a vibration beyond the hearing threshold. It produces strong vibration, high speed, strong cavitation effect and stirring effect; Therefore, it can destroy the cells of medicinal plants and make the solvent penetrate into the cells of medicinal materials, thus accelerating the dissolution of effective ingredients in medicinal materials into the solvent, so as to improve the extraction rate of effective ingredients. At the same time, compared with the effective components proposed by conventional methods, the structural changes of the effective components extracted by ultrasound were investigated. According to the literature, the effective components obtained by the two methods were compared and analyzed by thin-layer chromatography, infrared spectroscopy and nuclear magnetic resonance spectroscopy. The two obtained the same chromatograms, indicating that ultrasonic extraction would not change the structure of the effective components, shorten the extraction time, and improve the extraction rate, thus providing a rapid and high-yield new method for the extraction of Chinese herbal medicine components.

2. Application of ultrasonic technology in the extraction of chinese herbal medicine components

2.1 Extracting saponin components The saponin components are usually extracted by adding water or soaking in organic solvent, which takes a long time and has a low extraction rate. The ultrasonic technology can shorten the extraction time and improve the extraction rate. Song Xiaomei et al. extracted the main effective component of Gynostemma pentaphyllum saponins from Gynostemma pedunculatum. With 75% ethanol reflux as the control, ultrasonic extraction for three times, each time for 80 min, could significantly improve the yield of Gynostemma pentaphyllum saponins; Shao Jinggou et al. extracted Codonopsis saponins from Codonopsis pilosula. Compared with the conventional solvent immersion method, the extraction rate of Codonopsis pilosula saponins from the fine powder of Codonopsis pilosula after ultrasonic treatment for 40 min was more than one time higher than that of the conventional method (methanol cold soak for 48 h), and the time was shortened by 98.6%. In addition, the amount of crude Codonopsis pilosula saponins extracted by ultrasonic was nearly twice that of the conventional method, and the purity was also high; Relevant experts mentioned the main effective ingredient dioscin from the rhizome of Dioscorea nipponica. Soak it in 70% ethanol for 48 hours as a control, extract it with 20 kHz ultrasonic for 30 minutes, the extraction rate is 12 times that of the control, and extract it with 1 MHz ultrasonic for 30 minutes, the extraction rate is 1.34 times that of the control group, which can save 23.4% of the medicinal materials. It can be seen that ultrasonic extraction of saponins has the advantages of time saving, medicine saving, less impurities and high extraction rate.

2.2 Extraction of alkaloid components The extraction of alkaloids from traditional Chinese herbal medicines takes a long time and has a low yield. However, good results can be obtained after ultrasonic treatment. Berberine was extracted from Phellodendron amurense. The extraction rate was 18.26% higher than that of the control group after soaking in saturated lime water for 24 hours and extracting for 30 minutes with 20 kHz ultrasonic wave, and the structure of berberine did not change; Guo Xiaowu et al. extracted berberine from rhizome of Coptis chinensis, and the experiment proved that ultrasonic method was superior to immersion method, that is, ultrasonic treatment with 20kHz for 30min, and the extraction rate was as high as 8.12%. In the Chinese Pharmacopoeia (1985 edition), the toxic components of trichosanthin (strychnine) and brucine were extracted by ultrasonic technology, and it was clearly stipulated that in the determination of drug content, ultrasonic treatment for 40 min was equivalent to cold soak for 24 h. It can be seen that the extraction process of alkaloids by ultrasonic technology is simple, time-saving and has a high extraction rate.

2.3 Extraction of flavonoid components The flavonoid components are usually extracted by adding water and boiling, alkali extraction and acid precipitation, or ethanol and methanol immersion extraction, which is time-consuming, labor-intensive and low extraction rate, while ultrasonic extraction can improve the extraction rate and shorten the extraction time. The main effective component baicalin was extracted from the rhizome of Scutellaria baicalensis Georgi. With water as the solvent, the extraction rate of ultrasonic extraction for 10 min was higher than that of boiling with water for 3 h. The extraction rate of baicalin extracted with 20 kHz ultrasonic wave for 40 min was higher. Rutin was extracted from Sophora japonica for 40 min by ultrasonic extraction, and the extraction rate was 22.53%, 1.7-2 times that of the current large-scale production. The comparative test shows that it can save 30-40% of the medicinal materials and has high economic benefits.

2.4 The anthraquinone derivatives extracted from plants have complex forms. Free and bound forms often coexist in the same Chinese herbal medicine. Generally, ethanol or dilute alkaline aqueous solution is used for extraction. The effective components are destroyed due to prolonged heating, which affects the extraction rate. The anthraquinones of rhubarb are extracted from rhubarb. Compared with the conventional strong boiling method, the anthraquinones extracted by ultrasonic method for 10 minutes are higher than those extracted by decoction method for 3 hours. At the same time, the extraction rate of ultrasonic extraction with a frequency of 20 kHz is higher. In the extraction process of the compound Shouwu oral liquid, the ultrasonic extraction is used for the polygonum multiflorum, rhubarb and senna leaves containing a large number of anthraquinones derivatives, so as to avoid the failure of anthraquinones glycosides to destroy the effective components due to long decoction.