Croton nepetaefolius is a plant native from northeastern Brazil and belongs to Euphorbiaceae family. The
essential oil of this plant is widely used in folk medicine from the treatment of gastrointestinal disorders to
the use as an antiseptic agent, with an antifungal action scientifically proven. The action of this plant has been
extensively explored by the scientific community, being the secondary metabolites, which are responsible
for their properties, alkaloids, diterpenes, and triterpenes. The aim of this study was to evaluate the ability
of the secondary metabolite, casbane diterpene (CD) (isolated of the species mentioned above), to inhibit
microbial growth and biofilm formation of several clinical relevant species (about 15 species among bacteria
and fungi). Minimal inhibitory concentration was assessed by the standard technique of microdilution and
biofilm inhibition was tested using microtiter plates with biomass quantification by crystal violet staining
method. It was found that the CD possessed biocidal and biostatic activity for the majority of the species
screened, with the minimal concentration active between 125 and 500 mg/L. Moreover, CD anti-biofilm action
was also observed for some of the species. In addition, it was noticed some biofilm formation inhibition even
when the planktonic growth was not significantly affected. In conclusion it can be speculated that casbane
diterpene shows potential to be a natural tool for the treatment of diseases caused by different infectious
microorganisms
