| Rhodiola is the root of crassulaceae Rhodiola crenulata (Hook.f.et Thoms.)H.Ohba. It is registered in Pharmacopoeia of People's Republic of China (edition in 2005). Rhodiola is a usual Traditional Chinese Medicine for treating deficiency of vital energy, stagnation of blood, thoracic obstruction, cardialgia, apoplexy and hemiplegia, lassitude and asthma.The optimal process conditions of extraction and purification for total tannins in Rhodiola were researched in this article, as well as the quality standard. The content and results of the experiments were presented in detail.1. Establishment of a method for determining total tannins in RhodiolaObjective: To establish a method for determining the content of total tannins in Rhodiola. Methods: First of all, the concentration of alkaline solution was optimized and the absorbance result of casein (without extract) was also obtained. On the basis of these, the absorbance results of the reference standard solutions for gallic acid were measured by spectrophotometer at the wavelength attained via scanning. In the experiment, the test solution of phosphor-molybdenum-tungstic acid was used as developer. The standard curve was established at last. Results: The concentration of alkaline solution was 20%, the absorbance result of casein was 0.18. The concentration of gallic acid ranged from 2 to 10μg/ml had better linear relationship with the absorbance. And the results of precision, stability, reproducibility and recovery were consistent with the regulations. Conclusions: This method is able to determine the content of total tannins in Rhodiola because it is convenient, fast, and accurate.2. Study on extraction process of the total tannins in RhodiolaObjective: To obtain the optimal process conditions of extraction total tannins. Methods: The factors influenced the extraction effect severely were carried out first through single factor experiment, including temperature, the particle size, extraction methods and the solvent. The orthogonal experiments were done on the basis of the single factor results. The content of total tannins and the dry extraction ratio were taken as target and the factors including contact time, soak time, solvent-to-solid ratio, the extraction times were researched. The optimal process conditions were achieved lastly through analysis of variance. Results: The optimal conditions were as follows: the Rhodiola was sieved through 40 screen mesh, and soaked 20min with water 15 times as much as materials, extracted 3 times at 50℃, 1h every time. The content of total tannins reached to 7.97%. The extraction times played a significant role in determining the extraction result. Conclusions: Good reproducibility of the extraction process was shown and the operations are mild and simple enough to extract total tannins in Rhodiola. 3. Study on purification process of the total tannins in RhodiolaObjective: To optimize the conditions and parameters of purification process. Methods: In the first place, ethanol was applied to precipitate the impurities such as polysaccharide. The transferring ratio of total tannins and the yield of dried solid were taken as target to research the conditions. Then the macroporous resin technology was used to refine further. The conditions were optimized by using the content of total tannins, adsorption ratio, desorption ratio as targets. Results: The optimal ethanol conditions were as follows: the extract was condensed till that the material and physic liquor ratio was 1:3, then added 95% ethanol into the extract till the ethanol content was 80%(v/v), finally put it in cold-storage for 12h. The content of total tannins reached to 29.13% and the dry extraction ratio degraded to 16.14% after this. The optimal parameters of macroporous resin were as follows: the content of total tannins was about 3mg/ml, the flow rate was 2ml/min, the eluant was 50% ethanol, and the flow rate of eluting was 2.5ml/min and the amount of eluant was 4BV. The content of total tannins reached to 71.08% lastly. Conclusions: The ethanol method together with macroporous resin technology for purifying total tannins is stable and has high depuration ratio. So it can be used to purify total tannins in Rhodiola.4. Study on quality standard of total tannins in RhodiolaObjective: To study the quality control methods for total tannins in Rhodiola. Methods: The gallic acid was identified by use of thin layer chromatography (TLC). The contents of heavy metals were determined by atomic absorption spectrophotometer (AAS), including copper, iron, and lead. And the content of arsenic salt was checked according to the first method in Pharmacopoeia of People's Republic of China. The content of total tannins and gallic acid before and after hydrolyzed were determined by spectrophotometric method together with high performance liquid chromatography (HPLC). Results: The TLC result was observed at 254nm, and the speckle was gray corresponding with the gallic acid showed. The developer was 1%FeCl3 and the speckle turned into blue and black. The contents of heavy metals were all less than 10μg/g, and the content of arsenic salt was less than 2μg/g. The results were consistent with the regulations. The content of total tannins reached to 71.49% determined by spectrophotometric method, and the content of gallic acid before and after hydrolyzed were 3.211mg/g and 102.618mg/g respectivetly determined by HPLC. Conclusions: The quality can be controlled better via the items including identification, detection, and assaying. It will be the foundation of more research about total tannins.
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