1 Department of Natural Product Chemistry, Key Lab of Chemical Biology of Ministry of Education, School of Pharmaceutical Sciences, Shandong University, Jinan, 250012, China.
2 School of Pharmacy, Linyi University, Linyi, 276000, China.
3 Department of Natural Product Chemistry, Key Lab of Chemical Biology of Ministry of Education, School of Pharmaceutical Sciences, Shandong University, Jinan, 250012, China. Electronic address: louhongxiang@sdu.edu.cn.