Study on the method of separation and preparation purine alkaloids , noncaffeine tea polyphenols and tea pigments in one-step by sephadex LH-20

A simple and clean method of separation and preparation purine alkaloids,noncaffeine tea polyphenols and tea pigments from green tea by sephadex LH-20 column chromatography was developed. Distilled water was used as the eluting agent for purine alkaloids and tea pigments in the first stepwise elution,and tea polyphenols was eluted with 60%(v/v) ethanol solution by using reversed flow in the second stepwise elution. The yield of purine alkaloids was 3.14% with the 93.87% caffeine and 6.08% theobromine. The yield of tea polyphenols was 12.27% with the purity about 98.13% and the content of catechins was 90.28%. The content of EGCG which had the strongest antioxidant activity was 61.17%,and the content of caffeine in tea polyphenols had not been detected by high-performance liquid chromatography(HPLC). The recovery of tea polyphenols and purine alkaloids by column chromatography were 98.14% and 86.36% respectively. The byproduct of tea pigment containing polyphenol oxides and flavonoid glycosides mixture,can be used as natural pigments.