1. Department of Pharmaceutics and Biopharmacy, Philipps-University of Marburg, Ketzerbach 63, D-35032 Marburg, Germany, Department of Chemistry, Hans-Meerwein-Street, Philipps-University of Marburg, D-35032 Marburg, Germany, and Department of Pharmacy, Shenyang Pharmaceutical University, Wenhua Road 103, 110016 Shenyang, China