Obtenção e caracterização de extratos das folhas de Pitangueira (Eugenia uniflora L.) e avaliação na prevenção da oxidação lipídica

Abstract

In this work extracts of pitanga leaf, Eugenia uniflora L., were obtained in Soxhlet extractor with ethanol, methanol, acetone and n-hexane as solvents in order to evaluate which extract has better antioxidant capacity and better action in the prevention of linoleic acid oxidation through the thiobarbituric acid reactive substances content. All extracts were evaluated for total phenolic compound content by spectrophotometric method, as well as identification and quantification by high performance liquid chromatography (HPLC). The antioxidant activity of the extracts was determined based on the DPPH radical method and through the ferric ion reduction (FRAP). The results showed significantlyinfluencesof solvent nature in the extract yield, showing a tendency of increase with solventpolarity, being the methanol extract with 28% yield, followed by the ethanol extract with 22%, and the lower yield with n-hexane, 7%. The content of phenolic compounds varied in the range of 118 - 25 mg AG / g of extract, the ethanol extract obtained the highest result. Chromatographic analysis revealed the polyphenol presence such as catechin, gallic acid, epicatechin, caffeic acid, vanillic acid, p-coumaric acid, resveratrol and mirecithin. The antioxidant capacity of the extracts showed a high correlation with the total phenol content, varying according to the solvent used, and the antioxidant capacity of the extracts in ethanol, acetone and methanol was similar to the synthetic antioxidant BHT. The extracts in ethanol, methanol and acetone stood out in preventing the linoleic acid oxidation even when applied at lower concentration (200 ppm), results in the same order as those obtained with the artificial antioxidant BHT at the same concentration of the extracts. The n-hexane extract stood out only at the highest concentration, 1000 ppm. The results show the antioxidant potential of pitanga leaves in the reducer of lipid oxidation being another alternative for the food industry.