The chemistry analysis of the compounds present in dichloromethane and ethanolic fraction as well as bioassays enables to unde durability differences of Eperua falcata and Eperua grandiflora. The principal distinction between these two species is the acidic sut diterpenoic extract, which is antifungic in Eperua falcata when tested in in-vitro conditions. This study also enables to show tha fraction plays an important role in the mechanism of natural durability. It also reports the first isolation of cativic acid in Eperua falcata wood.