Study On Supercritical Carbon Dioxide Extracting And Crystallizing Andrographolide

Andrographolide is an important active ingredient from Chinese herb-Andrographis paniculate (Burm) Nees, which is required very high quality, especial purity, to develop new type injection. In order to separate and purify andrographolide in high efficiency, the author chooses extract of Andrographis paniculate (Burm) Nees as experimental material, investigating the mechanism of supercritical fluid extraction and crystallization, analyzing the influence factors; With HPLC (High perfomance liquid chromatography), SEM (Sacning electron microscope), XRD (X-ray diffraction), IR (Infrary), et al., analyzing and studying the effect of extraction and crystallization pressure, temperature, time, CO2 flux and the structure of crystallization ware on purity, crystallization ratio, crystal morphology, crystallization degree, molecule structure of andrographolide, and so on; also optimizing the correlative processing technology with response surface methodology(RSM); Investigating the means of enhancing supercritical fluid extraction and crystallization, such as entrainer, magnetic field, recrystallization.All theoretic analysis and experimental results are as follows:(1) The technology of supercritical CO2 extraction and crystallization can separate and purify andrographolide from extract of Andrographis paniculate (Burm) Nees; the purity of the product is more than 98% after three times extraction and crystallization.(2) Andrographolide formed by supercritical CO2 extraction and crystallization is distributed on the crystal board in purity grads.(3) According to the speciality of supercritical fluid extraction and crystallization, we analyze the principle of extraction and crystallization from surface adsorption, crystal nucleus formation, crystal growth and gradient crystallization: (1)crystallization ware comes into a surface adsorbing field for extraction and crystallization, which can debase interface activation energy, inducing adsorption crystallization, so crystallization ware is one of main factors that influence extraction and crystallization; (2)As crystal nucleus is forming and crystal is growing, temperature and pressure can influence supersaturation and energy bulkwark of crystal nucleus formation, and that outside fields, such as magnetic field, electric field, can also influence energy bulkwark of crystal nucleus formation; (3) As gradient crystallization goes, different matter quality from components in solute and different effects between component and crystallizationboard surface can form different damping to moving coefficient, resulting in gradient crystallization and separation.(4) According to the principle analysis of extraction and crystallization, author finds three main outer factors which can influence extraction and crystallization: (I) technology conditions, thereinto pressure and temperature can influence extraction and crystallization with positive and negative function, (II) the structure of crystallization ware including material, distance between crystallization board and surface shape can also influence extraction and crystallization, (Ill)outer fields, such as magnetic field, electric field, can influence extraction and crystallization with positive and negative function, too.(5) When temperature is 55 *C, time 90min, CO2 flux 15L/min, and the pressure is less than 25MPa? the higher the pressure, the higher the purity of on the upside of crystallization board with supercritical CO2 extraction and crystallization; With the increase of pressure, comparative crystallization mass on the upside is firstly increasing, when pressure is more than 15MPa (material purity 90%), crystallization mass then decreasing; with the increase of pressure, the particle size is smaller and smaller and more and more ruleless; According to XRD analysis, with the increase of pressure, the diffraction peak of impurity is decreasing, while the intensity of diffraction peak from andrographolide increasing, that is, the crystallization degree is improved with the increase of pressure; According to IR analysis, molecule structure of andrographolide is not changed with the increase of pressure. When the pressure is more than 25MPa. the extraction of andrographolide is in predominance, which can weaken crystallization function, thus many andrographolide is found in separation container.(6) We select the technology conditions that pressure is 16MPa, time 90min, CO2 flux 15L/min, and temperature changes between 35 "C and 65 "C , when temperature is 55X^, the purity of andrographolide is highest, what's more, the moderate increase of temperature is advantageous to improve the particle size and the homogenization of crystal and to shorten the time of crystallization; but too high temperature can decrease the purity of andrographolide; According to XRD analysis, the crystallization degree is improved with the increase of pressure; According to IR analysis, molecule structure of andrographolide is not changed with the increase of temperature.(7) When pressure is 16MPa, temperature 55'C, CO2 flux 15L/min, the increase of time is advantageous to improve the purity of andrographolide and crystal morphology; But too long time would depress the efficiency, so we select time 90min as extraction and crystallization condition.(8) When pressure is 16MPa, temperature 55'C, time 90min, the increse of CO2 flux makes for andrographolide crystallization to some extent, also forshortening time of extraction and crystallization; While the CO₂ flux is more than some value, which could reduce the purity of andrographolide.(9) For the first time, the model of technology of supercritical CO2 extraction and crystallization is built with Response Surface Methodology(RSM), which is advantageous to select technology parameters, such as pressure of 15-20MPa, temperature of 50-60 ℃ , time of 60-90min, the quality of andrographolide is better, the purity and the crystallization ratio of andrographolide is higher.(10) The board made of stainless steel is preferentially selected from plain glass, ground glass and stainless steel as crystallization board, the crystallization ratio and the purity of andrographolide is the best; moreover the crystallization ratio is increased with the increasing of the ratio of height to diameter, while the purity change indistinctively, especially the pressure exceed 20MPa, so we select the ratio of height to diameter from 6:1 to 8:1; Increasing the width between crystallization boards, the crystallization ratio of andrographolide is firstly increased, then decreased, the purity also change indistinctively, the moderate width between boards is from 0.4 to 0.6cm ; From the downside of the crystallization board to the upside, the morphology of crystal particulate is more and more regular, the diameter of particulate is bigger and bigger.(11) Entraine, magnetic fieldr, recrystallization all can enhance the effect of extraction and crystallization of andrographolide: (a) Selecting ethyl acetate as entrainer from ethanol, acetone, petrohol, ethyl acetate, this effect of separation and purification of andrographolide is best, moreover, realizing the unification of extraction solvent and entrainer, and can eliminate the pollution between solvents;(b) Magnetic field enhancing can improve supercritical CO2 extraction and crystallization. On condition that temperature is 55℃, time 60min, CO2 flux 15L/min, magnetic field intensity 0.1T, when pressure changes is from 8MPa to 16MPa, crystallization ratio of andrographolide is increased about 5% to without magnetic field; ( c ) Recrystallization not only improve the purity of andrographolide, also improve the crystallization technology parameters, especially debasing pressure; The crystal particle by recrystallization is reunited in floccule, which is advantageous to improve the solubility of the crystal particulate.(12) When pressure is 16MPa, temperature 55℃ , time 90min, CO2 flux 15 L/min in first extraction and crystallization, and recrystallization pressure is 14MPa, temperature 55℃, time 60min, CO2 flux 15 L/min, after three times extraction and crystallization, we can obtain 98% andrographolide; According to analysis, we find that the results of Elementar and UV (Ultraviolet) are basically consistent with document reports and standard sample, and the result of IR iswholly consistent with standard sample.To sum up, we can use the technology of supercritical CO2 extraction and crystallization to separate and purify andrographolide and some other active ingredients from natural materials, and can obtain "green" and safe products with high quality, which is advantageous to be used to develop high grade medicine, food, healthy food.