1. Key Laboratory of Pu-er Tea Science, Ministry of Education; Yunnan Agricultural University; Kunming 650201 China
2. State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany; Chinese Academy of Sciences; Kunming 650201 China
3. Key Laboratory of Medicinal Chemistry for Nature Resource, Ministry of Education, School of Chemical Science and Technology; Yunnan University; Kunming 650091 China
4. Department of Chemistry; Lakehead University; 955 Oliver Road Thunder Bay ON P7B 5E1 Canada