Study On Analysis Method And Resources Of O-Methylated EGCG In Tea

O-Methylated catechin is a kind of catechin, It mainly includes EGCG3 "Me and EGCG4" Me. EGCG3 "Me and EGCG4" Me are a kind of white powder,which can be dissolved in water and organic solvents easily.They are derivatives of EGCg.The molecular structures are (-)-epicatechin-3-O-(3-O-Methyl) gallate(EGCG3 "Me) and (-)-epicatechin-3-O-(4-O-Methyl) gallate(EGCG4" Me) respectively.They have shown efficient anti-allergic effect, especially on anti-pollen-allergic action.This research aims at establishing an accurate and efficient method of O-Methylated EGCG by the HPLC and using this method to analyzing the content of tea. Thus we can screen out some higher O-Methylated EGCG content tea plant varieties and resourses which grow in hunan province.We also discuss some factor which affect the content of methylated EGCG.This study has an important theoretical significance and practical value on O-Methylated EGCG research and utilization.The study has acquired the following conclusions:1,Established the HPLC method to determining the content of O-Methylated EGCG(EGCG3 "Me and EGCG4" Me) in tea. The optimum condition was as follows:Kromasil C18 column;mobile phase:0.02mmol/L KH2PO4-H3PO4 buffer solution(pH=2.5) and acetonitrile;wavelength:278nm;flow rate:1.0ml/min;column temperature:30℃. This method showed good linearity for both EGCG3 "Me and EGCG4" Me.The result demonstrated that this method is precise,accurate and can be used for the determination of methylated EGCG. 2,This study analyzed 117 kinds of tea samples from different source. Among these tea samples,only 16 kinds of tea's content was under detection limit (0.01%), which accounted for 13.7%, the highest one is C48,whose content reached for 1.7%.Only 10 kinds of tea samples contained EGCG4" Me, which accounted for 8.5%,the highest one is C45,whose content reached for 0.55%, the lowest content is C69,whose content is only 0.036%.3,We use two kinds of method(steaming fixing and freeze drying) to dispose the same tea sample.The EGCG3 "Me average content of steaming fixing sample is 0.120%,while the freeze drying sample is 0.127%,The result showed different fixing method has no definite effect on the content of EGCG3 "Me. 4,Through determination of tea leaves which picked in different season. We have found that the content of EGCG3" Me in the same variety also has definite difference. Summer is the highest and second in autumn, lowest in spring.5,The content of EGCG3 "Me in different parts of tea leaves was also significantly different and has the highest in the fourth leaf and the third leaf, followed by the fifth leaf and the lowest content in tea stalk.6,During the course of processing green tea,different processing procedure has a definite effect on the content of EGCG3 "Me.The content of EGCG3" Me was higher in spreaded leaves,droped in fixing leaves,keeped constant in rolled leaves and droped in dried leaves again.but the range is small.