Avaliação do perfil antioxidante de extratos aquoso e etanólico de Phyllanthus niruri IN VITRO

Abstract

Medicinal plants are widely used by people since ancient and in folk medicine due its therapeutics effects and benefits to health. We know today that these effects are due to constituents of plant compounds, such as phenolics compounds and flavonoids, substances with proven antioxidant activity. Among these vegetables, Phyllanthus niruri is a plant popularly known as “stone-breaker” and used in teas and infusions for the treatment of several disorders; however, are not well understood the mechanisms involved in the action of extracts of this plant, especially in in vitro assays. Thus, the mechanisms of antioxidant activity of aqueous and ethanolic extracts of P. niruri against the generation of several radical species and lipid peroxidations under in vitro conditions were investigated. The inhibitory activity of DPPH radical, the protective effect in the deoxyribose degradation assay and inhibition of nitric oxide radical were evaluated. Also tested the interaction of iron ions with extracts for the ability of the extracts to chelate Fe2+ and Fe3+ reduction, as well as the protective effect on Fe2+-induced lipid peroxidation in TBARS assay. We also evaluated amount of phenolic compounds and flavonoids present in each extract. The results show that the extracts have significant (p <0.05) inhibitory activity against various radical generating systems. The extracts also interact significantly (p <0.05) in the chelation and reduction of iron ions as well as are capable to reduce significantly (p <0.05) Fe2+-induced lipid peroxidation in phospholipids, contributing to the hypothesis that extracts may be acting on the redox chemistry of iron ions. Additionally, we quantified the content of flavonoids and phenolic compounds present in the extracts, compounds which is given the antioxidant potential of the plant. In general, the results demonstrate that the extracts have been antioxidant activity, but this activity is dependent from tested concentration, by the nature of the extract (aqueous or ethanolic) and the evaluated essay. From this, we suggest that the antioxidant properties of the extracts may be related to the inhibitory action of different radical species and interaction with the redox chemistry of iron ions by interfering with the generation of free radicals systems.