Compositional analysis and preliminary toxicological evaluation of a tea polysaccharide conjugate

Tea polysaccharide conjugate is one of the main bioactive constituents of tea (Camellia sinensis L.). The chemical composition and preliminary toxicological evaluation of a tea polysaccharide conjugate was investigated to determine the possibility of using it for human consumption. Chemical analysis of tea polysaccharide conjugate showed that the tea polysaccharide conjugate was a nonstarch protein bounded acidic polysaccharide. The protein, neutral sugar, and uronic acid content of the tea polysaccharide conjugate was 3.5%, 44.2%, and 43.1%, respectively. The contents of iron, magnesium, zinc, and selenium in the tea and its polysaccharide conjugate were measured by inductively coupled plasma-optical emission spectrometry (ICP-OES). Results showed that the contents of four elements in tea polysaccharide conjugate were much higher than that of tea power. Especially, the content of iron in tea polysaccharide conjugate was increased 5.9 times. The tea polysaccharide conjugate, when fed to mice, was found to have no toxicity to the liver, kidney, heart, thymus, or spleen of the mice and none of the mice died throughout the period of the experiment. There was no significant difference between the thymus index, spleen index, and liver index of the mice from the test and control groups (P>0.05). On the basis of the study, the tea polysaccharide conjugate may be classified either as a very low toxicity substance, that is, GHS Category 5 (globally harmonized system), or as unclassified when orally administrated to mice. It might be a candidate of dietary supplements besides the bioactivities as a polysaccharide.