Studies On The Synthesis, Purification And Application Characterization Of Acetylated EGCG Derivatives

The widespread and important biological activities of green tea are often attributed to tea catechins, in particular, epigallocatechin gallate (EGCG). A lot of researche findings revealed that EGCG exhibited many potential pharmacological activities including antioxidant, anticarcinogenic, antibacterial, antivirus and the capacity to scavenge free radicals. However, the further applications of natural EGCG are restricted because its liposoluble is not high, unstability and low bioavailability in vivo. In order to optimize the structure of EGCG and improve its bioactivity, we systematically study on the synthesis, purification and application characterization of acetylated EGCG in this paper. The details are as fellows:First, the influential factors of synthesizing acetylated EGCG were investigated by single factor experiments. It was found that the effects of the reactant molar ratio is the most important one among all the reaction factors.The optimum synthetic reaction conditions were as follows: solvent D as solvent, acetic anhydride as acetylation solvent, pyridine as catalyst, by controlling the appropriate molar ratio of EGCG to acetic anhydride, the different degree of substitution of acetylated EGCG can be synthesized with the mixture stirred at room temperature for 5 hours. At the same time, we conduct the synthesis of the fully acetylated derivative of EGCG by regulating the appropriate molar ratio of EGCG to acetic anhydride, the yielw of acetylation production reached above 99.30%, EGCG was conversed high effectively.Based on the synthesis of acetylated EGCG derivatives, we conduct the study of preparation of the fully acetylated EGCG. The reaction mixture of goal products were obtained by controlling reactant conditions, then treated by the two-step method of purifying process including the primary acid, alkaline washing and the further column chromatography. The product purity of the two-step purification was respectively 85% and 96.04%, and its structure was confirmed by HPLC/MS. While scale-up experiments investigated and optimized relevant craft parameters of the synthesis of acetylated EGCG under the condition of the laboratory, the test results indicated that the synthetic technology of acetylated EGCG is stable and reliable. The acquired technology can be applied to the synthesis of acetylated EGCG, which possesses high conversion rate of EGCG and yield rate of acetylated products.At last, the results of application characteristics of acetylated EGCG concluded that it is relatively stable in the representative of esters, chlorinated hydrocarbons, ketones and alcohol; not sensitive to light, oxygen and temperature in laboratory conditions; unstable and easily degraded in the strong acid or alkali solution, stable under the conditions of neutral or weak acid and alkali solution. The affection of other factors were as follows: the acetylated EGCG has lower endurance capability against the reducing and oxidating agent; the ions on the stability of acetylated EGCG are also relatively good with the exception of carbonate and bicarbonate.Using EGCG as a lead compound, in order to improve the fat-soluble and bioavailability of acetylated EGCG derivatives, the development of high-activity and high application value product by structural modification is an important topic.