Metabólitos Secundários e ação antioxidante de Croton helliotripifolius e Croton blanchetianus

Antioxidants are compounds that, at optimal concentrations in relation to oxidable substrates, react with free radicals preventing or reducing oxidative stress. Many diseases and degenerative processes are associated with overproduction of free radicals. This stimulated several research groups to investigate the antioxidant potential of substances produced by several families of the world flora. This study identified the major classes of secondary metabolites present in ethanol leaf extracts of C. blanchetianus (Marmeleiro) and C. helliotripiifolius (Velame), and assessed their antioxidant potential. Ethanol extracts were obtained by the exhaustive extraction method cold and resulted in 3.29% and 3.26% extraction efficiency. Then phytochemical analyses were performed on the extracts to investigate the presence of tannins, flavonoids, flavonones, flavonols, catechins and xanthones. The antioxidant activity of extracts was determined by in vitro photocolorimetric method based on the sequestration of free radicals, using DPPH (1,1-diphenyl-2-picryl-hydrazyl). Both extracts were able to sequestrate DPPH free radical. Croton blanchetianus extract activity showed to be more efficient than BHT (Butylated Hidroxytoluene) (positive control), with EC50 = 6.5 ± 0.5 mg mL-1. Croton helliotripifolius extracts showed lower antioxidant activity, with EC50 = 50.15 ± 0.21 but still higher than that observed for BHT. However, the results observed for the ethanol extracts are possibly the result of the presence and concentration of phenolic compounds such as tannins and flavonoids, which were identified in this study.