1. Departments of Biochemistry and Chemistry, The Ohio State University, 876 Biological Sciences Building, 484 West 12th Avenue, Columbus, Ohio 43210, Division of Pharmaceutics, School of Pharmacy, The Ohio State University, 500 West 12th Avenue, Columbus, Ohio 43210, College of Life Science, Shandong University, Jinan, Shandong, 250100, P.R. China