The use of plants and their products for medical treatment is a quite common procedure in Brazil, especially for treatment of diabetes. In fact, several plants can demonstrate hypoglycemic effects in vitro assays. However, the use for human treatment requires the knowledge of their toxicological properties. The aim of this study was to evaluate the effect of protein extracts of Chrysobalanus icaco collected from natural habitats and of Eugenia astringens acquired from the market in Rio de Janeiro on the viability and migration of fibroblasts. E. astringens has a similar morphology as C. icaco and it is sold as Chrysobalanus in a popular market. Being a different plant, E. astringens expresses different proteins, and its protein extract has proved to possess higher toxic properties than C. icaco does. Cytotoxicity assays indicated that, as the protein extract concentration increases, fibroblast viability decreases. Only the E. astringens extract displayed cytotoxicity at all concentrations, in addition to reduced fibroblast migration. The results obtained in this study demonstrates that it is necessary integrative policies for rational use of medicinal plants and their commercialization, since the current use of medicinal plants may be inadequate, and it is of great importance for Public Health.