1. Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612, College of Pharmacy, University of Hawaii at Hilo, Hilo, Hawaii 96720, Natural Products Laboratory, Research Triangle Institute, Research Triangle Park, North Carolina 27709, and Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, Ohio 43210