Avaliação do teor de fenóis totais e atividade antioxidante da árvore Sabiá (Mimosa caesalpiniifolia) cultivada na fazenda escola do IFRN - Campus Apodi

Abstract

The use of medicinal plants to treat health problems has been going on since ancient times and remains very current. With the passage of time and the advancement of technology, the identification and the possibility of isolation of the substances responsible for phytotherapeutic activity became easier. Thus, the objective of the present work was to evaluate the content of phenolic compounds and antioxidant activity of extracts of the species Mimosa caesalpiniifolia, popularly known as thrush. This work was motivated by the records of the use of their peels in home medicine as a good treatment for bronchitis, in addition to presenting a healing aspect, and other diseases. The extracts were obtained by immersion in three solvents with different polarities (hexane, ethanol and water), being subsequently subjected to tests that showed evidence of the presence of compounds with antioxidant activity. The quantification of total phenols was done by the reaction of the extracts with Folin-ciocalteu reagent in a basic medium, while the determination of antioxidant activity used 2 different methods: the first consisted of inhibiting the DPPH radical activity by the action of the extract and the second was the ABTS·+ radical cation methodology was used. The best percentage yield in obtaining the crude extract was observed in general in aqueous extracts, with emphasis on the aqueous extract of the leaves with 11.24%. Regarding the total phenol content, the best result was related to the ethanolic extract of the branches, which presented a value equal to 33.64 mgEAG/g extract, which is considered a low value when compared to other plants with medicinal properties. Despite this, the antioxidant tests showed excellent results for both methodologies. The DPPH reaction test again highlights the ethanolic extract of the branches, with an IC50 value (inhibitory concentration of 50% of the radical) equal to 7.08 mg/L and then the aqueous extract of the barks with 9.38 mg/L. with the exception of hexane extracts, all showed activity close to the positive standards used (vitamin C: 43 mg/L and Trolox: 4 mg/L). As for the test with ABTS·+, the aqueous extracts of the branches and ethanolic of the branches (2658,57 µmol/L trolox/g) and the barks (2314,81 µmol/L trolox/g) showed the best results. In addition, it was also possible to observe a certain relationship between the concentration of phenols in the extracts and the total antioxidant activity (ABTS·+).