Abstract
We have determined 6 caffeic acid derivatives in order to study the seasonal differences of Ilex latifolia Thunb. leaves which are used to make Ku-ding cha in China. The current-year leaves (new ones) and old ones are obtained from male or female plants in the spring or autumn. Freeze-dried samples were extracted with 80% methanol and analyzed by HPLC. The leaves contain have no caffeine, but have some caffeic acid and 6 derivatives, including chlorogenic acid. The current-year spring leaves have high amounts of caffeic acid derivatives that range from 147—235 mg/g(dry weight), but the current-year autumn ones, old spring ones and old autumn ones have low amounts of are 36 mg/g (dw), 24—44 mg/g (dw) and 31 mg/g (dw) respectively. 4-O-caffeoyl quinic acid in the current-year leaves increased 3 to 6 times from spring to autumn. No new leaves were collected from the female plant because they did not germinate. Therefore, the contents of the caffeic acid derivatives in the female plant were similar to those in the old leaves in the male plant. These results of the caffeic acid derivatives suggest that the new spring leaves of Ilex latifolia Thunb. are a good source for antioxidants.
