Fracionamento bioguiado e identificação de compostos fenólicos antioxidantes em folhas de Pereskia aculeatta

Abstract

Pereskia aculeata Miller is a species with climbing characteristics, belonging to the Cactaceae family. This plant, resistant to drought and adapted to hot weather, is widely distributed in the South, Southeast, Midwest and Northeast regions of Brazil, being known in the country as Ora-pro-nobis. P. aculeata is extremely valuable from a nutritional point of view, however, there are still few studies on its phytochemical constitution. Within this context, this study evaluated the antioxidant potential of P. aculeata leaves, in addition to identifying, using high-performance liquid chromatography coupled with mass spectrometry, the possible compounds responsible for the bioactivity. A hydroalcoholic extract of P. aculeata leaves was obtained, and then this extract was fractionated using solvents of different polarities (hexane, dichloromethane, ethyl acetate, acetone and butanol). The extract and fractions were evaluated by ABTS, DPPH, FRAP methods and determination of total phenolic compounds. In addition, the substances present in them were identified and quantified using and HPLC-ESI-QTOF-MS/MS and HPLC-DAD, respectively. These analyzes showed that extracts obtained from more polar solvents showed the best results for antioxidant activity. The acetone and butanol fractions presented the best results for DPPH (229.41 and 236.48 μmol g-1, respectively) and FRAP (1343.17 and 1215.77 μmol FeSO4 g-1, respectively). Rutin and isoquercetin were the major compounds in the butanol and acetone fractions. While, caffeic acid and ferulic acid were the major compounds in the ethyl acetate and dichloromethane fraction, respectively. Quercetin-3-O-xyloside, Kaempferol-3-O-arabinoside, trehalose, feruloyltyramine, (10E,15E)-9,12,13-trihydroxyoctadeca-10,15-dienoic acid, 9,12,13- trihydroxyoctadec-10-enoic acid and 16-hydroxy-9-oxooctadeca-10,12,14- trienoic acid were identified by high-resolution masses and reported for the first time in P. aculeata samples. It is suggested that the best antioxidant activity found in the hydroalcoholic extract and in the acetone and butanol fractions of P. aculeata is due to the presence of rutin and isoquercetin in these samples. The good ABTS, DPPH and FRAP results obtained with the acetone and butanol fractions suggest that these samples can be used to continue studies of P. aculeata leaves.