Avaliação da atividade antioxidante e caracterização química dos extratos aquosos do caule e folhas de Vismia spp

Abstract

In recent years, the use of plant extracts from species of the Hypericaceae family has gained prominence due to their antioxidant potential and associated health benefits. In this context, the present study aims to analyze the chemical constituents and antioxidant activity of aqueous extracts from the stem and leaves of Vismia guianensis and Vismia cayennensis. To conduct this study, methodologies included the collection of plant material, followed by maceration, infusion, and lyophilization to preserve active compounds. Compound identification was performed using electrospray ionization mass spectrometry (ESI-MS). Antioxidant activity was assessed using the ABTS•+ and DPPH• radical assays, in addition to determining the total phenolic content of the samples. The mass spectrum of the Vismia guianensis sample revealed major peaks at m/z 447 [M–H]− allowing the identification of quercetin-O-deoxyhexoside, as well as taxifolin-deoxyhexoside at m/z 449 [M–H]- quinic acid at m/z 191 [M–H]- , and quercetin-pentoside at m/z 433 [M–H]−. In the Vismia cayennensis samples, analysis of the crude extract revealed a molecular ion peak at m/z 577 in negative mode, indicating the presence of a proanthocyanidin dimer, in addition to a major peak at m/z 289 [M–H]− corresponding to catechin, a compound belonging to the flavonoid class.The aqueous extract evaluated using the ABTS+ assay showed antioxidant activity for both samples of V. guianensis, with values of 2212.023 ± 0.0010801 µM ET for the stem and 2212 ± 0 µM ET for the leaves, while the stem and leaf extracts of V. cayennensis registered 1404.024 ± 0.014089 µM ET and 1404.033 ± 0.006014 µM ET, respectively. In the DPPH assay, V. cayennensis showed values of 1990.048 ± 0.000408 µM ET for the stem and 1990.04 ± 0.00108 µM ET for the leaves, while V. guianensis presented 1934.87 ± 0.003674 µM ET for the stem and 1934.871 ± 0.004301 µM ET for the leaves. For total phenolic content, values ranged from 333.66 to 333.69 mg GAE g⁻¹, indicating the presence of substances with antioxidant activity, such as phenolic compounds capable of binding to free radicals due to available hydrogens in their structure. This study provides significant scientific contributions regarding the chemical profile and antioxidant activity of extracts from Vismia species. The results expand knowledge about V. guianensis and V. cayennensis, contributing valuable data for scientific research dedicated to the discovery of new therapeutic agents.