Enzymatic Synthesis Of Egcg Acetate

Tea catechins are the important ingredients of tea polyphenols in green teas. Due to their widespread biological activity, antioxidant ability, the capability to remove free radicals, against cornary heart disease, atherosclerosis and cardiovascular disorder, more and more importance are attached to them.There are main four kinds of catechins monomers including EGCG、ECG、EGC、EC.The characteristic of water-soluble has impact the effects of tea catechins as antioxidant, especially in oil phase. It has been reported that there are chemical methods to change their molecule structure for improving their lipid-solubility. However, the chemical process exists many shortcoming such as the highly preparation cost, the fierce reaction condition, product variability and so on. We use the fixed lipases to carry on the molecule modification with EGCG to improve its lipid-solubility, has obtained the satisfied results.We screened the vinyl alcohol, the lauric acid ethylene ester as the acylation groups to esterificate EGCG and has obtained a good effect. The many kinds of lipases including NOVO435, RMIM, TLIM, LA201056, the laboratory self-restraint fixed lipase all can catalyze the synthesis reaction. The laboratory self-restraint fixed lipase had the best catalytic activity. The synthesis reaction got a better effect in the polar organic solvents including acetone, the ethyl acetate, THF etc. When Added the enzyme quantity was1-2times to EGCG quality, the substrate mole ratio of EGCG and a vinyl acetate is above1:5, took acetone as solvent medium, EGCG can nearly completely transform in24h.The products, EGCG acetate was a kind of mixtures which possessed the close molecule structure, similar characteristic. We have established the linear gradient elution HPLC conditions as the fundamental analysis method. Methods:The determination was carried out with KromasilC18(4.6mm i.d,250mm,5μm) column. The flow rate was1ml/min and the detective wavelength was at280nm. The mobile phase, A:CH3OH; B:H2O. The gradient procedure is25%A (10min)->enters the sample (30min)->60%A (10min)->25%A. The primary products were apart very well. The method is simple and accurate and can be completed in60minutes.The products molecule structure was identified by IR, LC-MS and1H-NMR. The LC-MS result showed there existed mono-、di-、tri-replaced products. The phenol hydroxyl of EGCG was substitutee by the group of CH3CO—. The infrared spectrum and the1H-NMR spectrum also indicated CH3CO—formed the ester key with EGCG.