Isolation and chemical characterisation of a polysaccharide from green tea (Camellia sinensis L.)

BACKGROUND: To contribute towards understanding the relationship of structure and bioactivity, a protein-bound acidic polysaccharide named TPC3-1 was isolated and purified from low-grade green tea (Camellia sinensis L.). The homogeneity and weight average molecular weight of TPC3-1 was determined by agarose gel electrophoresis and high-performance gel permeation chromatography. The monosaccharide and amino acid composition of TPC3-1 were analysed by gas chromatography and an amino acid analyser. The molecular structure of TPC3-1 was characterised by Fourier transform infrared spectroscopy, C-13 nuclear magnetic resonance spectroscopy and atomic force microscopy. RESULTS: Based on the data obtained, the average peak molecular weight of TPC3-1 was about 120 kDa. TPC3-1 was composed of L-arabinose, D-ribose, D-Xylose, D-glucose and D-galactose with a molar ratio of 4.9:2.2:3. 1:1.8:1.0. Fifteen amino acids were identified as components of the polymer. The TPC3-1 molecule was found to have an anomeric carbon sign of both alpha and beta configurations and high-branched chains. The network structure of TPC3-1 was observed. CONCLUSION: The tea polysaccharide TPC3-1 was an acid protein-bound polysaccharide with an image of network structure. The results presented here will facilitate further study of the relationship between the chemical structure and biological role of tea polysaccharide. (c) 2008 Society of Chemical Industry