1. Department of Medicinal Chemistry, School of Pharmacy, Qingdao University, Qingdao 266071, Shandong Province, China
2. UNMC Center for Drug Discovery, Department of Pharmaceutical Sciences, College of Pharmacy, Fred and Pamela Buffett Cancer Center, and Center for Staphylococcal Research, University of Nebraska Medical Center, Omaha, Nebraska 68198, United States