1. Department of Pharmacology and Toxicology, Division of Medicinal and Natural Products Chemistry, College of Pharmacy, University of Arizona, 1703 E. Mabel Street, Tucson, Arizona 85721-0207, Institute for Tuberculosis Research (M/C 964), College of Pharmacy, University of Illinois at Chicago, 833 S. Wood Street, Chicago, Illinois 60612-7231, and INTA, Instituto Nacional de Recursos Biológicos, Las Cabañas y Los Reseros s/n, 1712 Villa Udaondo, Castellar Buenos Aires, Argentina