Otimização da extração de compostos fenólicos com atividade antioxidante das folhas da Campomanesia xanthocarpa O. Berg. (Myrtaceae)

Abstract

Campomanesia xanthocarpa, known as guabirobeira, guavirova, guabiroba-miúda, and guabirobeira-do-mato, is a very common plant in the southern, southeastern, and central-west regions of Brazil. It produces a highly appreciated orange fruit by indigenous people. Its leaves are used in folk medicine to seek relief from infectious diseases, particularly urinary tract infections, and preliminary studies have shown that they can be used for the treatment of neurodegenerative, cardiovascular, and oncological diseases. This is due to the presence of phenolic compounds with antioxidant activity. So far, few studies have been conducted on the plant's leaves, and for this reason, this work aims to optimize the process of extracting phenolic compounds with antioxidant activity. In this study, a 22 factorial design was performed, where the dependent variables were the total phenolic content and the antioxidant activity evaluated by the DPPH radical scavenging method and the ferric reducing antioxidant power (FRAP), while the independent variables evaluated in the extraction process were time and the ethanol:water ratio. The antioxidant activity of the leaves ranged from 169.52 to 682.55 μmol Trolox g-1 by the DPPH radical scavenging method and from 649.85 to 1386.79 μmol Fe2+ g-1 by the ferric reduction method. The total phenolic content showed a variation from 14.96 to 57.02 mg GAE g-1 (GAE: Gallic Acid Equivalent). Thus, it was possible to define the best extraction condition, which was the lower level of ethanol concentration (20%). Afterward, the extracts with the lowest and highest antioxidant activity were injected into the high-performance liquid chromatograph (HPLC) for the identification and quantification of compounds within the plant's complex matrix, revealing the presence of gallic acid, catechin, rutin, isoquercetin, and astragaline.