Composition and characterization of an acidic polysaccharide from out-of-date tea leaves

Abstract

An acidic polysaccharide conjugate from the tea leaves ( Camellia sinensis) beyond the useful date was isolated and characterized. The crude polysaccharides (TPS) were extracted with hot water and separated on a DEAE sepharose FF gel filtration column to obtain ATPS2. The chemical structure of ATPS2 was investigated by GC, IC, HPGPC, IR, UV, Periodate oxidation–Smith degradation, 1H NMR, and 13C NMR methods and its conformation was observed with Congo red test. The crude TPS mainly consisted of 5 peaks with molecular weights of 7.67 × 10 5, 2.03 × 10 5, 2.83 × 10 4, 3470.2, and 1205.52 Da, respectively. The molecular weight of ATPS2 was determined as 7.4 × 10 5 Da by HPGPC. IC chromatogram of ATPS2 showed that ATPS2 consisted of rhamnose, arabinose, xylose, mannose, glucose, galactose and galacturonic acid. Compared with the crude TPS, ribose and glucuronic acid were not found in ATPS2. Periodate oxidation–Smith degradation results showed that ATPS2 is a linear (1→3) β- d-Glc main chain linkage with 1→ or 1→6-linked chains and there are no 1→2 or 1→4-linked chains. The main glycosyl residues of ATPS2 were α-, β-configuration, including signal of β- d-Galp, α- l-Araf, α- d-Manp, α-Rhap, and α- d-Glcp. Congo red test exhibited that ATPS2 did not have a triple-helical conformation.