1. Department of Oral Medicine and Diagnostic Sciences, College of Dentistry, and Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, Chicago, Il 60612, and Departamento de Química Orgânica e Inorgânica, Universidade Federal do Ceará, 60.451-970, Fortaleza-CE, Caixa Postal 60021, Brazil