In vitro antioxidant capability of white tea ethanol extracts

To investigate the antioxidant capability and cellular protective effect of Fuding white tea ethanol extracts(WTEE). Total tea polyphenols and flavonoids in WTEE were determinedby chemical colorimetry assay.The antioxidant capability of WTEE was evaluated according to the 1,1-diphenyl-2-picrylhydrazyl(DPPH)scavenging assay,superoxide anion scavenging assay and reducing power assay,respectively. Cellular protective effect of WTEE was investigated using a model of hydrogenperoxide(H₂O₂,150 μmol/L)induced oxidativestress in intestinal epithelial Caco-2 cells.Cell viability was determined by MTT assay. The cellular levels of superoxide dismutase(SOD),and glutathione peroxidase(GSH-Px)were determined by commercial assay kits according the manuscripts.The cellular levels of malondiadehycle(MDA)were determined by thiobarbituric acid reactive substance(TBARS)assay. WTEE were enriched in total tea polyphenols(343.00±27.90 mg gallic acid/g)and flavonoids(24.95±0.56 mg rutin/g). WTEE exhibited a great DPPH(ES₅₀ 330.63 μg/mL)and superoxide anion scavenging activity(EC₅₀ 342.90 μg/mL)and total reducing power. In addition,WTEE was able to increase the cell viability(to 85.6%)in oxidative damaged Caco-2 cells exposed to H₂O₂. The WTEE treatment also increased the cellular levels of SOD and GSH-Px,and reduced the oxidative damaged related MDA generation in H₂O₂ treated Caco-2 cells. Overall,the great in vitro antioxidant capability and cellular protective effect of WTEE was associated with the high levels of total tea polyphenols and flavonoids.