Functional groups and antioxidant activities of polysaccharides from five categories of tea

Ten polysaccharides were extracted from five categories of tea with hot water and further fractionated by stepwise ethanol precipitation. The polysaccharides were characterized by Fourier transform infrared spectroscopy (FT-IR) and the components including sulfuric radical, aminohexose and uronic acid were determined. All analyzed polysaccharides had antioxidant activities, with polysaccharides-II being stronger than polysaccharides-I and the antioxidant activity of the tea polysaccharides was closely related with the contents of functional groups in the polysaccharides. Our results suggest that the tea polysaccharides could be explored as a potential antioxidant agent for use in medicine or functional foods. On the other hand, the different antioxidant activities of samples provided an important reference for choosing the suitable kind of tea in application.