| Carotenoids belong to an important class of natural pigments responsible for the coloration of many plant and animal species. These pigments have lots of important biological activities. These biological activities and sources of Carotenoids, lutein, zeaxanthin and astaxanthin reviewed in this thesis.This paper relates to a process for preparing the significant value of zeaxanthin and astaxanthin from lutein which is isolated from extracts of marigold flowers provided by Guangzhou leader Bio-Technology CO. LTD. The process consists of the following two parts.The first part describes a base-catalyzed isomerization of lutein gave zeaxanthin. The step also includes optimization of technic parameters. The results show that the optimal reaction condition is as follows:using 1,2-Propanediol as solvent, reaction time for 168 h and reaction temperature at 110℃, under inert atmosphere. The ratio of 1,2-Propanediol to lutein is 20, Potassium Hydroxide to lutein is 6. According to HPLC analysis, the yield of zeaxanthin can reach 93% under the optimal condition. In addition, zeaxanthin obtained from lutein eaters by one step in excellent yield.The second part demonstrates a novel conversion of zeaxanthin directly to astaxanthin, which includes contacting the zeaxanthin with iodine in the presence of sodium bromic and can be accomplished in one chemical step. The organic solvent is chloroform, and react for 12 h at about 30℃, under inert atmosphere. The final substrates were identified and qualitied with HPLC, HPLC-MS and 1H NMR. The concentration of product is up to 69%. |
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