Composition, characteristic and activity of rare earth element-bound polysaccharide from tea

The compositions and structural characteristics of rare earth elements-bound polysaccharides from tea (REE-TPS) were studied with the methods of Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Gas Chromatography (GC) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy. The results show that polysaccharide from tea (TPS) was a sort of glycoprotein and coordinated with Rare Earth Elements (REE) closely. The sugar fraction was composed of Rha, Ara, Xyl, Fuc, Glc, and Gal. There existed almost all natural amino acids with Glx, Asx, and Hyp as the major parts in the protein fraction. The REEs in REE-TPS were mainly composed of La, Ce, and Nd, especially, more than 75% of them was La. The coordination atom of the first coordination shell of La in REE-TPS was oxygen, the coordination number of which was 6, and the average distance between the atoms was 2.52 A. The second shell was formed from sulfur atoms, the coordination number and the average distance were 3 and 2.91 A, respectively. The bio-experiments show that REE-TPS could decrease the content of blood glucose in mice significantly.