| A herb called Eucommia ulmoides leaf has been contained in "Chinese Pharmacopoeia"(in the first part of 2005 version) because of its wide physiological activities. Chlorogenic acid is one of the main active compounds of Eucommia ulmoides leaf, and also is one of the functional components whose major activity are the high oxidation resistance. Then the method of alcohol extraction and resin column separation has been chosen for extraction and separation of these phenolic acid compounds, but there are some shortcomings, such as not high purity of target components, severe column contamination, low sample recovery and so on. In the practical applications, fields of application and effects of chlorogenic acid and other phenolic acids are limited greatly due to they dissolve in water easily but in lipids difficultly. This study has established a preparation method of phenolic acid compounds (chlorogenic acid in this study) whose purity are high by microwave assisted extraction and HSCCC separation and purification. Meanwhile, the issue has studied the molecular modification method about chlorogenic acid in order to enhancing its fat-soluble, based on keeping its original functional activities. The main research contents and the results are as follows:(1) The extraction method of Eucommia ulmoides leaf chlorogenic acid was optimized based on the analysis of single-factor tests and by response surface methodology. The optimum extraction conditions were as follows:extraction time, 12min; the wattage,420W; ethanol concentration,75%; and the liquid/material ratio, 30:1. Under these conditions, chlorogenic acid extraction rate reached to 3.59±0.08 %; compared with traditional extraction, the extraction rate increased by 50%; and compared with ultrasonic extraction, the extraction rate increased by 8.2%.(2)The high purity chlorogenic acid was extracted from Eucommia ulmoides leaf by high-speed counter current chromatography. In order to ensure the optimum conditions of HSCCC, analyze the determination results of the target compounds partition coefficient in the solvent system, the two-phase solvent system stratified time and fixed retention rate. The best HSCCC conditions were as follows:the two-phase solvent system, ethyl acetate-butanol-water (3:1:4); the speed,900r/min; the flow rate,2.0mL/min; and the temperature,30℃. Under this condition, chlorogenic acid whose purity reached to 98.7% was prepared only by one step HSCCC separation. Compared with column separation, the superiorities of the above method are the target product in higher purity, few column contamination, easier operation, higher reproducibility and shorter time-consuming.(3) The molecular modification method of Lauryl chloride and chlorogenic acid was optimized based on the analysis of single-factor tests and by orthogonal test. The optimum molecular modification conditions were as follows:chlorogenic acid/fat chloride molar ratio,1:1; reaction time,8h; temperature,35℃; the catalyst triethylamine/chloro genie acid molar ratio,1.5:1; and the amount of solvent/chlorogenic acid,20mL/g. Under these conditions, the yield of modified product was 91.51%. In addition, the product structure was identified by IR and MS.(4)The fat-soluble and antioxidant activity of Chlorogenic acid and its molecules modified products were evaluated. For the reactions between fatty acyl chloride with different lengths of carbon chain and Chlorogenic acid, the reaction time-consuming and the fat-soluble of their products increased as the carbon chain length increased. Compared with the antioxidant activity of different compounds, the result showed Vc > CGP (chlorogenic palmitate)-CGM (chlorogenic myristate)>CGL (chlorogenic laurate)> CGD (chlorogenic decanoate)> CGA (chlorogenic acid), which verify that the molecular modification of chlorogenic acid increased the fat-soluble without reducing its antioxidant activity. |
PDF Full Text Request