Study On Extraction Processes Of Total Alkaloids From Semen Strychni

Semen strychni has been used as a chinese medicine for a long history, which is bitter taste and mesothermal category with channel tropism of liver and spleen. It also has many effects including anti-inflammatory and analgesic of activating meridians stop pain, welling of the lymph node. Clinically, it is widely used in the rheumatism obstinate rheumatism, traumatic injury from fall, post-polio syndrome, rheumatoid arthritis, diseases of nervous system, cancer, chronic bronchitis and various chronic aplastic anemia. Therefore, Semen strychni was widely used in chinese traditional medicines and has been proved to have prominent curative effects in the clinic.Alkaloids are the key active agents in Semen strychni with contents of 1.5-5%. This thesis focused on the microwave-assisted and ultrasonic-assisted extraction processes of alkaloids from Semen strychni. The influences on extraction efficiency of the alkaloids, including Semen strychni grain diameter, solvent concentration, solvent pH, ratio of liquid to solid, ultrasonic/microwave power and extraction time, were analyzed. Based on the signal factor investigation, a polynomial quadratic model was set up by the principles of the central composite design and the Response surface analysis methodology (RSM) to optimize the extraction conditions.The optimal conditions of microwave-assisted extraction of alkaloids from Semen strychni was determined as follows:Semen strychni grain diameter was 20 mesh, ratio of liquid to solid was 6:1, steeping time before microwave-assisted extraction was 30 min, solvent pH was 7.0, microwave power was 240 W, extraction time was 6.7 min, ethanol concentration was 58.8%(v).Meanwhile the optimal conditions of ultrasonic-assisted extraction of alkaloids from Semen strychni was concluded as follows:Semen strychni grain diameter was 20 mesh, ethanol concentration was 32.3%(v), solvent pH was 5.0, ultrasonic-assisted extraction time was 37min, ultrasonic power was 300W and ratio of liquid to solid was 10:1.Comparing with the traditional techniques of heat reflux extraction, the microwave-assisted and ultrasonic-assisted extraction processes of alkaloids from Semen strychni have many advantages with lower temperature, less solvent and time consumption, energy conservation and environmental protection.Furthermore, the two-phase system method of ethanol/dipotassium phosphate aqueous with ultrasonic-assisted extraction for extracting alkaloids from Semen strychni was studied in this thesis. The results showed that the alkaloids was greatly located in the ethanol phase. The optimal extraction conditions in the ethanol/ dipotassium phosphate aqueous two-phase system were determined as follows: ethanol mass fraction was 28%, dipotassium phosphate mass fraction was 24%, solvent pH was 9.0, temperature was 25℃, ultrasonic power was 300 W and ultrasonic-assisted extraction time was 37 min. Under aboved mention condtions, the extraction efficiency of total alkaloid can be up to 89.48%.