Phenolic antioxidants from green tea produced from Camellia crassicolumna Var. multiplex

Camellia crassicolumna var. multiplex (Chang et Tan) Ming belonging to Camellia sect. Thea (Theaceae), is endemic to the southeastern area of Yunnan province, China, where the leaves have been commonly used for making tea and beverages consumed widely. HPLC analysis showed that there was no caffeine or theophylline contained in the leaves; however, thin layer chromatography (TLC) analysis suggested the abundant existence of phenolic compounds. Further detailed chemical investigation of the green tea produced from the leaves of the plant led to the identification of 18 phenolic compounds, including four flavan-3-ols (1-4), six flavonol glycosides (5-10), three hydrolyzable tannins (11-13), two chlorogenic acid derivatives (14, 15), and three simple phenolic compounds (16-18). The isolated compounds were evaluated for their antioxidant activities by 1,1'-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and tyrosinase inhibitory assays. Most of them exhibited significant DPPH radical scavenging activities, whereas flavan-3-ols and hydrolyzable tannins showed stronger inhibitory activities on tyrosinase. The results suggest that C. crassicolumna could be an ideal plant resource for a noncaffeine beverage.