Intensified Extraction Of Active Constituents From Several Chinese Herbs By Inner Ebullition And Its Evaluation

In China, the medicinal plant resources are abundant, and numerous industries are utilizing the superiority of resources to produce Chinese traditional medicine. However, due to different production processes, many companies had large disparities in the efficiency and the quality of production. By far, decocting method and alcohol refluxing extraction are popular in most of the factories. Although the cost on the investment of equipment is saved, some disadvantages are clear:such as low efficiency, poor quality of the products and large consumptions of energy as well as organic solvents, which restricted the development of the companies. A few companies improved their manufacturing techniques and applied new extraction and separation technologies, for instance, extractions with supercritical CO2, microwave-assist and ultrasonic-assist, etc. But the operational cost increases with the higher equipment investment and energy consumption. For the purpose of solving these problems, a method called inner ebullition was proposed by our research team in2004. It is approved to achieve good results in separation of active constituents from some medicinal plants. The study for inner ebullition still needs to be improved, though.Concerning the advantage of rapid extraction at a low temperature, inner ebullition was utilized for expanding its application fields:firstly, lentinus edodes, ganoderma lucidum fungus and fructus, which active constituents belong to polymer polysaccharides, were selected in this study. The evaluations of the adaptability on the extraction of polysaccharides were given by the results of single factor experiments and the comparison with the conventional decoction. Meanwhile, taking gymnema sylvestre and andrographis paniculata for example, the applications of inner ebullition in extraction of medicinal plants with high content of pigments were studied. The effects of inner ebullition on the regenerability for the macroporous absorbent resin were also investigated. In addition, the proper kinetics models were selected and the kinetics equations were simulated, according to the mass manner of convection-diffusion for inner ebullition. Then, Taking salvia miltiorrhiza, pueraria root and notoginseng for example, the kinetic equations were fitted and the mass transfer coefficient was calculated. On the basis of the extraction kinetics, the thermodynamic parameters were investigated, which provided theoretical support for inner ebullition. Finally, in order to compare with other extraction methods, HPLC fingerprints of honeysuckle, notoginseng and andrographis paniculata were constructed respectively, which were taken as tools with the specific constituents to make an evaluation. The fuzzy mathematics was also used to make a comprehensive evaluation for different extraction methods, which provides some useful information for selecting extraction technology of Chinese herbs.The result shows the method of inner ebullition is able to be applied in the extraction of polysaccharide polymer. In particular, the decompressing inner ebullition can achieve the selective extraction for those medical plants of which active constituent belongs to acetate-soluble polysaccharides while have a high content of reducing sugar. This process can save the consumption of organic solvents. On the other hand, the inner ebullition can reduce the yield of pigment during the extraction process and relieve the pressure to the following purification process. Thus, inner ebullition contributes to prolong the service life of macroporous absorbent resin. With regard to the extraction kinetics, the mass transfer coefficient of inner ebullition was in the range of0.07～0.14s-1, which affected little by temperature. Apart from that, the mass transfer coefficients in the broken and integrity area of plant cells were very similar, which reflected the characteristic of convection. Compared with ultrasonic-assisted extraction, inner ebullition obviously accelerated the extraction rate of inner diffusion and made the mass transfer coefficient100times more than that of ultrasonic-assisted. Undoubtedly, the energy barriers were cut down and active energies were reduced during the extraction process of inner ebullition, which helped the extraction process. To be more specific, the inner ebullition is a spontaneous, endothermic process with entropy increase, which can be certified by the thermodynamic parameters as follows:ΔH, ΔS>0; ΔG<0., it can also be found in the HPLC fingerprint and the comparison with several similarity evaluation systems. The result demonstrates that inner ebullition not only ensured the extraction ratio of the specific constituents, but also several kinds of active constituents can be extracted simultaneously. The results were similar to the leaching with methanol. It was very important to preserve the active components as much as possible and to reflect the theory of Chinese medicine-"monarch, minister, assistant and guide". In addition, by applying the fuzzy mathematics, and considering some factors such as the quality of the products, extraction efficiency and required equipment investment, the following evaluation indexes such as fuzzy matrix and weight matrix were proposed. They were used to compare those different extraction methods, namely, inner ebullition extraction (under atmospheric), traditional decocting method, methanol cold-maceration, ultrasonic-assisted extraction, microwave-assisted extraction were compared. The result shows that inner ebullition is better than other processes, which has a great potential to promotion.This study shows that inner ebullition can be widely applied in the medicinal plants, achieving their active components with rapid and environment-friendly extraction. In the near future, inner ebullition is believed to be widely used in the industry because of its great advantages.