1. Chemistry Department, Federal University of Viçosa, Avenida P.H. Rolfs, CEP 36570-000, Viçosa, MG, Brazil, Chemistry Department, Federal University of Minas Gerais, Avenida Antônio Carlos, 6627, CEP 31270-9001, Belo Horizonte, MG, Brazil, and Department of Biology & Evolution, University of Ferrara, via L. Borsari 46, I-44100 Ferrara, Italy