1. Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Pharmaceutical Science, Jiangnan University, Wuxi 214122, P. R. China
2. Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, P. R. China
3. College of Chemistry, Fuzhou University, Fuzhou 350108, P. R. China