Avaliação das propriedades antioxidante e anticâncer do extrato aquoso da casca do caule de Stryphnodendron adstringens

Abstract

Stryphnodendron adstringens (Mart.) Coville (Fabaceae) is a tree species native to the Brazilian Cerrado, commonly known as barbatimão or casca-da-mocidade. In traditional medicine, decoctions or infusions of the stem bark of this plant are used in the treatment of several diseases. The objective of this study was to investigate the chemical composition of the aqueous extract of the stem bark of Stryphnodendron adstringens (EASA), to evaluate the antioxidant and anticancer properties, as well as to characterize the mechanisms of death promoted against B16F10Nex-2 murine melanoma cells. Stryphnodendron stem bark were collected in the State of Mato Grosso do Sul, Brazil, and then macerated with distilled water for 48 hours to obtain the aqueous extract, SAAE. Identification of the chemical constituents was determined by LC-DAD-MS and the quantification of phenolic compounds and flavonoids present in the SAAE were determined by the colorimetric methods FolinCiocalteau and aluminum chloride, respectively. The antioxidant activity of SAAE was investigated using the monocation of 2,2'-azinobis- (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals, inhibition of oxidative hemolysis and inhibition of lipid peroxidation induced by 2,2'-azobis (2- amidinopropane) (AAPH) in human erythrocytes. B16F10Nex-2 murine melanoma cells were used to evaluate the anticancer action and mechanisms involved in the cell death promoted by the SAAE. From the SAAE, gallic acid, gallocatechin, epigallocatechin, isomeric chromones C-hexosyl- and O-pentosyl-5,7- dihydroxychromone, dimeric and trimeric proanthocyanidins mainly composed of prodelphidin units and the were identified. The concentrations of phenolic compounds were 197.10 ± 0.83 mg EAG / g SAAE and for flavonoids were 2.87 ± 0.08 mg EQ / g. The antioxidant capacity by the ABTS assay demonstrated that SAAE was able to inhibit 50% of the radicals (IC50) at a concentration of 1.83 ± 0.15 μg / mL and maximal inhibition of free radicals of 99.68 ± 0.08% at the concentration of 10 μg / mL. In the DPPH assay, SAAE presented IC50 at the concentration of 3.81 ± 0.02 μg / mL and maximum inhibition of 89.92 ± 1.36% at the concentration of 50 μg / mL. These results corroborate with those obtained in the AAPH assay, where SAAE showed anti-hemolytic action activity and decreased malondialdehyde content in human erythrocytes throughout the experimental period (240 min) in concentration and time dependent manner. In the evaluation of cytotoxicity, the presented cytotoxic action against the B16F10Nex-2 melanoma cells at the concentration of 65 μg / mL after the treatment of 24 and 48 h, the observed cell death profile being the late apoptosis. The investigation of the mechanisms of cell death promoted by showed an increase in intracellular ROS levels, dysfunction of the mitochondrial membrane potential and activation of caspase-3. Together, these data show antioxidant and anticancer effects of the aqueous extract from the stem bark of Stryphnodendron astringens, results that open new perspectives for investigations against other tumor cell lines, in vivo models, as well as for the identification and isolation of the responsible chemical constituents for these purposes.