Abstract: The functional components of different dark tea extracts (Tianjian tea, Fuzhuan tea, Bailiang tea, Liubao tea and Pu-erh tea) were quantified and the functional properties, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability, oxygen radical absorbance capacity (ORAC), and the protective effect against injury in PC12 cells, were evaluated. Then the relationship between functional components and properties in tea extracts was analyzed. The results showed that the contents of tea polyphenols, polysaccharides and catechins in Fuzhuan tea, Tianjian tea and Bailiang tea extracts were significantly higher than those in Pu-erh tea and Liubao tea extracts, while Puer tea extract contained the highest contents of caffine, gallic acid and theanine. Fuzhuan tea, Tianjian tea and Bailiang tea extracts had higher ORAC and DPPH radical scavenging activities, whereas Fuzhuan, Puer and Liubao extracts had stronger protective effects against injury in PC12 cells. Correlation analysis indicated that DPPH radical scavenging activity and ORAC activity were significantly influenced by the contents of tea polyphenols, especially the contents of epicatechin?gallate (ECG) and epigallocatechin gallate (EGCG), while the protective effects against glutamate-induced injury in PC12 cells were significantly related to the content of theanine.

Key words: dark tea extracts, functional components, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, oxygen radical absorbance capacity (ORAC), PC12 cells