Phenolic Antioxidants from the Leaves of Camellia pachyandra Hu

Camellia pachyandra Hu. is a species in Camellia sect. Heterogenea (Theaceae), whose leaves have been used for making tea and consumed by the local people living in Yunnan province, China. This is the first investigation of the chemical constituents in the leaves of C. pachyandra, from which 22 phenolic compounds including nine hydrolyzable tannins (1-9), 11 flavonol glycosides (10-20), and two simple phenolics (21, 22) were isolated. It was noted that the leaves of the title plant contained no caffeine and no catechin, whereas hydrolyzable tannins were found to be the major constituents, of which the content of ellagitannin 5 reached to 3.7%. All the isolates were evaluated for their antioxidant activities by DPPH radical scavenging and tyrosinase inhibitory assays. Though the secondary metabolites without caffeine and catechins are different from the commonly consumed tea plants, the results suggested that the leaves of C. pachyandra, rich in hydrolyzable tannins as potent antioxidants, could be developed as an ideal resource for a natural beverage without caffeine.