1. School of Pharmaceutical Sciences & Institute of Materia Medica, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan 250117, Shandong, P. R. China
2. School of Chemistry and Pharmaceutical Engineering, Shandong First Medical University, Shandong Academy of Medical Sciences, Taian 271016, Shandong, P. R. China
3. Department of Applied Chemistry, China Agricultural University, Beijing 100193, China