Caracterização química e avaliação da atividade antioxidante de extratos das folhas de Eugenia uniflora L.

Abstract

Eugenia uniflora L. (Myrtaceae), popularly known as pitangueira, is native to Brazil and recognized as a source of bioactive compounds, moreover polyphenols.

Reactive species are unstable oxidizing agents that promote oxidative stress. Plant- derived antioxidants, such as phenolic compounds, act as powerful antioxidants,

mitigating oxidative stress. Due to the several factors that influence the composition of their extracts, such as genotypic and phenotypic characteristics, assigning antioxidant properties to specimens present in distinct locations under different conditions is of great importance. In this study, essential oils were characterized using gas chromatography coupled with mass spectrometry (GC-MS), and leaf extracts were characterized by determining total phenolic compounds, total flavonoids, and liquid chromatography coupled with mass spectrometry (LC-MS) of three specimens of E. uniflora (EU1, EU2, and EU3). The antioxidant potential of the extracts was evaluated using different methods (DPPH, ABTS, HOCl, ORAC, CUPRAC, FRAP, and phosphomolybdenum method). Computational calculations (DFT/M062X/6-311+G*) were also performed to evaluate the antioxidant properties of seven compounds present in E. uniflora extracts. Approximately 60 compounds were identified in the essential oils, and the presence of 13 compounds was proposed in the extracts. The results indicated that extracts obtained with ethyl acetate (EtOAc) at pH 4 showed higher efficiency in attenuating reactive species and electron donation due to their higher concentration of phenolic acids. Additionally, through computational chemistry and the evaluation of antioxidant activity in EtOAc/MeOH extracts, it was concluded that glycosylated flavonoids contribute with lower intensity, compared to phenolic acids, to the antioxidant potential of E. uniflora. The investigation conducted with the three specimens contributes to the analysis of chemical variability and its impact on the biological activities of E. uniflora.