Limin Mao^{1, 2}, Shuhong Shao¹, Shili Sun³, Yuefei Wang^{1, 2}, Ping Xu¹, Liewei Cai^{1, 4,}

Two fractions of polysaccharides, named PTPS-1 and PTPS-2, was extracted and purified from puerh tea by Sephacryl S-300 column chromatography. The physicochemical properties of these two polysaccharides were investigated by high-performance liquid chromatography (HPLC), Fourier Transform IR spectra, scanning electron microscope (SEM) and atomic force microscope (AFM). Analysis of chemical compositions (protein, neutral sugars, uronic acid and monosaccharide composition) suggested that they were both kinds of acid heteropolysaccharides bound with protein, and contained seven monosaccharides with different molar ratio. Meanwhile, evaluation of antioxidant activities by in vitro assays of DPPH, ABTS and FRAP showed that PTPS-1 demonstrated stronger antioxidant ability than PTPS-2. Similarly, PTPS-1 exhibited remarkable inhibitory potential on α-glycosidase in vitro, significantly stronger than that of PTPS-2 and acarbose. Moreover, the results from animal test indicated PTPS-1 possessed significant inhibition on postprandial hyperglycemia in diabetic mice compared with the model group.

puerh tea polysaccharides, purification, antioxidant activity, α-glycosidase inhibition, physicochemical characterization