Who knows how to extract alkali from alkali-containing plants?

Traditional methods for extracting 1. 1 alkaloids.

Choosing suitable extraction methods is of great significance for preparing alkaloids and maintaining the activity of effective components. According to the solid-liquid contact state, the traditional methods currently used can be divided into static methods (such as decoction and soaking) and dynamic methods (such as reflux and percolation) [4].

1. 1. 1 decoction

Decocting method is one of the earliest and most commonly used preparation methods of traditional Chinese medicine. It is suitable for medicinal materials whose effective components are soluble in water and insensitive to heating, and can extract relatively more effective components.

Huang Jiwei et al. [5] decocted in acid water, and optimized the extraction process of Sophora Tonkinensis by orthogonal test with the extraction rate of matrine and oxymatrine as the index. M.G. Ortega et al. [6] studied the extraction of alkaloids from Huperzia (a medicinal plant of Huperzia). Using decocting method, 80g of dried and crushed medicinal materials were decocted in 600 mL boiling water twice, each time for 65438 0 h, the extractive solutions were combined, alkalized, then extracted with chloroform, and the organic phase was evaporated to obtain 0.25 g of total alkaloids.

1. 1.2 impregnation

The extraction method can soak medicinal materials at room temperature or heating conditions to obtain effective components, which is simple and easy to operate, but it takes a long time, requires a lot of solvents and has low extraction rate of effective components. Soaking at room temperature is a common method to extract alkaloids. For example, Qin et al. [7] studied the cold extraction conditions of alkaloids from Sophora alopecuroides seeds. The total alkaloids in Sophora alopecuroides seeds were extracted with dilute hydrochloric acid at room temperature. The leaching rate of total alkaloids under different conditions was studied, and the highest was above 3.7%. Chen et al. [8] optimized the extraction method of total alkaloids from Cortex Phellodendri with berberine as the index. Using water, ethanol and acid as solvents respectively, the extraction rate of ethanol is 84.4%, which is much higher than the other two solvents.

1. 1.3 Reflux

Circulating method is to use volatile organic solvents such as ethanol as solvent to heat and distill the leaching solution, in which the volatile solvent is distilled and condensed again, and then returned to the extractor to continue to participate in the leaching process, which is mostly completed by Soxhlet extractor. The method has simple operation and high extraction rate. Long Deqing et al. [9] extracted total alkaloids from konjac by acid-alcohol reflux method, and obtained the best technological conditions: reflux in acid-alcohol with pH value of 2 ~ 3 for 3 hours, and the total alkaloid content was 0.39%. Reflux method is not suitable for the extraction of heat-sensitive alkaloids because it takes a long time and the whole process is in a heating state.

1. 1.4 percolation

Percolation extraction process is similar to multiple leaching process, the leaching solution can reach a higher concentration and the leaching effect is better. The method does not need to be heated at room temperature, has low solvent consumption and low filtration requirements, simplifies the separation operation process, and is especially suitable for the extraction of valuable medicinal materials with heat sensitivity, volatility and low content of effective components. The extraction rate of alkaloids can be ensured by percolating coptis chinensis with 0.5% sulfuric acid solution and collecting percolate for 7 times. Compared with reflux method, percolation method has less impurities, higher extraction rate and less solvent consumption [10]. Percolation requires high operation technology, otherwise it will affect the extraction efficiency. This method should not be used when the extract is viscous and difficult to flow.