Abstract:

Post-fermented dark tea processes have been shown to generate mainly polymeric polyphenolic substancesdue to its special pile fermentation during manufacturing. Polymeric polyphenols from dark tea were fractionated andtheir antioxidant activity and anti-cancer capacity were investigated. Five dark tea polymeric polyphenol fractions (DPPs)were prepared from the aqueous extract of dark tea by liquid-liquid extraction, and the method of fractional precipitationemploying mixtures of methanol/acetone-diethyl ether. All the DPPs exhibited a slightly acidic property and had a similarskeleton structure. They showed significant antioxidant activity and three of them had a strong inhibitory activity onproliferation of HT-29 tumor cells. The use of the fractional precipitation method employing the mixtures of methanol/acetone-diethyl ether provided several fractions rich in phenolic components from dark tea, which exhibited significantantioxidant activity and cytotoxicity on HT-29 cells.

Key words: dark tea Camellia sinensis var. Baiye Dancong, polymeric polyphenol, antioxidant activity, cytotoxicity