Separation And Identification Of Trigalloylglucose(TGG)and Screening Of Tea Resources With High Level Of TGG

Galloylglucoses are important functional ingredients in many Chinese herbal medicines. However, few studies have been reported because of their low concentration in normal tea. Based on exporing new tea plant resoures with high level of galloylglucoses, in this study, a galloylglucose-type compound had been separated and purified from these materials, then identification of its chemical structure and antioxidant capacity was conducted by using UPLC/MS/MS, NMR and other technologies. Quantitative analysis of the target compound and catechins in the collected tea resources had been carried out after a relevant UPLC/MS/MS detection method had been established. The major results can be summarized as follows:(1) Most of the EGCG and ECG in extracts had been removed and the target compound can be partially purified by application of thin layer chromatography in which200-300mesh silica gel and n-butanol/water (3/1) were used as immobile phase and developing agent. The UPLC/MS result showed that the target compound possesses two ultraviolet absorbance peaks at around219nm and278nm and its molecular weight is636with daughter ions at m/zl69,313,465and483under ES-mode. Highly purified (>97%) target compound was also obtained by using preparative chromatography in which YMC-Pack ODS-A column and acetic acid-acetonitrile-water solution with optimized elution time program were used as immobile phase and eluant. The compound was identified as2,3,6-Tri-O-galloyl-b-D-glucose (TGG) by1H-NMR,13C-NMR, and its molecular formula was predicted as C27H24O18.(2) In three kinds of antioxidant systems, the antioxidant capacity of TGG is significantly higher than ascorbic acids, while slightly less than EGCG.(3) ES-model is more suitable for the detection of catechins and TGG than ES+. High response of the ions can be obtained when the cone voltage is set to20-3Ov. Epimer of catechins has similary daughter ions and compound with galloyl group has a same daughter ion at m/z169. A UPLC/MS/MS method had been established and applied to quantify the TGG and catechins in collected more than190tea plant resources. Eight individuals with TGG level high than30mg/g were obtained, in which TGG level of individual "FZ1" and "FZ2" is between40and50mg/g and that of "1-017" and "1-018" is higher than50mg/g. Two individuals with EGCG higher than140mg/g and four individuals with total catechins higher than230mg/g were also screened. TGG level of individual "FZ2" decreased, while EGCG increased with increase in shoot maturity, indicating fluctuation of theses compounds might be involved in development of the shoots.