| Following is a summary of the work performed in my PhD program. This work consists of the preparative isolation and purification of catechins and theanine from green tea extract. It is one part of the project of "Research and Development in series of products extracted from green tea". This project has won the first prize of Hunan science and technology progress. This paper focuses on the preparative isolation and purification of catechins and theanine, which has medical value, and discusses the following questions.1. A preparative counter-current chromatography apparatus was made in our lab., with which we successfully isolated and purified the catechins from green tea extract and increased the amount of preparation, according to the principle of counter-current chromatography. We also identified the structures of the products. Two pairs of two-phase solvent systems were used. One solvent system was petroleum ethyl-ether acetate and water at volume ratios of 0.2:1:2 and the other was n-butanol-ethyl acetate and water at volume rations of 0.2:1:2.2. The preparative counter-current chromatography theory has been studied. The choice of solvent system was confirmed according to the solvents delamination time and the K value, and the anticipation of the order of coming out has also been studied.3. We have had a deep study on the theanine in tea, and developed a direct analysis method of theanine with high performance liquid chromatography. We successfully isolated and purified the theanine from green tea extract with preparative high performance liquid chromatography. The purity of theanine products is up to 98% as was determined with analytical high performance liquid chromatography. The yield of theanine in each run of the preparative HPLC method was 70.4%. The structure of the product was identified again in accordance with the literature.4. The optimization of chromatography conditions and amplification of the technology have also been discussed in the paper. |
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