1. Department of Chemistry, Division of Chemical Biology and Medicinal Chemistry, and Department of Pharmacology; University of North Carolina; Chapel Hill NC 27599 USA
2. Current address: Department of Chemistry, 300 Science & Technology Building; East Carolina University; Greenville NC 27858 USA
3. Current address: Center for Nanotechnology in Drug Delivery, Department of Molecular Pharmaceutics, Eshelman School of Pharmacy; University of North Carolina; Chapel Hill NC 27599 USA
4. Current address: KBI Biopharma; 1101 Hamlin Rd Durham NC 27704 USA
5. Current address: Skaggs School of Pharmacy; University of Colorado; 12850 E. Montview Blvd Aurora CO 80045 USA