Impact of internal metal ions in tea polysaccharides on antioxidant potential and suppression of cancer cell growth.

Four kinds of tea polysaccharides (MBTPS, MGTPS, ZBTPS, ZGTPS) were extracted from Maofeng black tea, Maofeng green tea,Ziyan black tea and Ziyan green tea, and then four tea polysaccharides (RMBTPS, RMGTPS, RZBTPS, RZGTPS) after metal removal were prepared. The physicochemical properties, antioxidant activity and inhibitory activity on cancer cell proliferation of the above polysaccharides were studied. The composition analysis shows that these tea polysaccharides were glycoproteins complexes, composed of a variety of monosaccharides, and the removal of metal ions did not lead to fundamental changes in the composition of polysaccharides. In vitro activity, after removing metal ions, the ABTS free radicals scavenging ability and reducing power of tea polysaccharides were decreased, and the inhibitory effect on proliferation of H22 cells weakened. There was a great correlation between metal elements Al and Ni and biological activity. The results showed that the metal ions in tea polysaccharides, especially Al and Ni, had positive effects on biological activity.

Antioxidant and hypoglycemic activity of tea polysaccharides with different degrees of fermentation.

Four polysaccharides (GTPS, OTPS, BTPS and DTPS) were extracted from green tea, oolong tea, black tea and dark tea respectively. The physical and chemical properties, antioxidant and hypoglycemic activities were studied. Structural analysis showed that these tea polysaccharides were glycoprotein complexes, and there were significant differences in microstructure, protein, total sugar and uronic acid content. They were all composed of multiple monosaccharides and different molar ratios. In terms of antioxidant activity, completely fermented BTPS and DTPS had higher activity. Regarding to hypoglycemic effects, BTPS showed higher α-glucosidase inhibitory activity in vitro. And in the treatment of type 2 diabetes mice, Oral BTPS significantly controlled the levels of blood glucose, TG, TC, LDL-C, Cr, UREA, ALT and AST in diabetic mice, and improved insulin resistance. Histopathological observation further confirmed that BTPS can alleviate liver injury caused by hyperglycemia and hyperlipidemia. Data showed that BTPS significantly improved hyperglycemia and liver function in diabetic mice.