1. School of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650500, P.R. China
2. Department of Chemistry and Engineering, Wenshan University, Wenshan 663000, P.R. China
3. Yunnan Research Institute of Tobacco Science, Kunming 650106, P.R. China
4. School of Pharmacy, Kunming Medical University, Kunming 650500, P.R. China