1. Department of Pharmaceutics, People's Hospital of Rizhao, Rizhao 276826, P.R. China
2. Department of Neurosurgery, People's Hospital of Rizhao, Rizhao 276826, P.R. China
3. Department of Natural Medicinal Chemistry, Institute of Materia Medica, Shandong Academy of Medical Sciences, Jinan 250062, P.R. China