1. Key Laboratory of Coal Resources Exploration and Comprehensive Utilization, Ministry of Natural Resources, College of Chemistry and Chemical Engineering Xi'an University of Science and Technology No. 58 Yanta Road Xi'an 710054 P. R. China
2. Key Laboratory of Tropical Translational Medicine of Ministry of Education, Hainan Provincial Key Laboratory for Research and Development of Tropical Herbs, Haikou Key Laboratory of Li Nationality Medicine, School of Pharmacy Hainan Medical University No. 3 Xueyuan Road Haikou 571199 P. R. China