1. Division of Pharmaceutics, College of Pharmacy, Department of Chemistry and Biochemistry, Division of Medicinal Chemistry and Pharmacognosy, Department of Pathology, The Ohio State University, Columbus, Ohio 43210; School of Chemistry and Environmental Sciences, Henan Normal University, Xinxiang, Henan 453007, P. R. China; and Laboratory of Cell Biology, National Cancer Institute, National Institute of Health, Bethesda, Maryland 20892