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Investigation of phenolic constituents in Echinacea purpurea grown in China.

Echinacea is a North American native medicinal herb. In 1990 s, it was introduced in China. Nowadays, Echinacea is growing successfully in a number of places in China, and has been used as a crude drug. However, the phytochemical variation in the plant grown in China has not been studied. In this study, the contents of total phenolics and caffeic acid derivatives in aerial parts and roots of Echinacea purpurea grown in China were investigated by high-performance liquid chromatography (HPLC) and colorimetric analysis. The effects of different drying methods on the components were also studied. The results show that the content of caffeic acid derivatives in E. purpurea reached its highest in the middle stage of full blossoming. The content of caffeic acid derivatives in fresh raw material was generally higher than that in dried raw material. There was no significant difference in the content of caffeic acid derivatives among three geographical populations of E. purpurea. Furthermore, the developmental pattern of total phenolics in E. purpurea was the same as that of caffeic acid derivatives. The stage of mid-bloom is an optimal harvesting period for both caffeic acid derivatives and total phenolics. In addition, the results show that the fresh raw material is the optimal material for pharmaceutical purposes, and that the optimal pharmaceutical parts are the roots, leaves and flowers.