Extração e caracterização de metabólitos secundários de Aloysia gratissima (Gillies & Hook.) Tronc

Abstract

Aloysia gratissima, popularly known by the name of “Garupá” in the southern region of America, where it is native, is a plant widely used in folk medicine and already has many of its scientifically confirmed properties. Due to its importance as a potential phytotherapic agent, the present work aims to extract and characterize the secondary compounds present in A. gratissima. Thus, the leaves of the plant were subjected to extraction with distilled water and hydroacoolic, in order to isolate and structurally identify the main chemical constituents present in their leaves in different forms of extraction. The supernatant was separated with refrigerated ethanol and centrifuged from the higher molecular weight precipitants. The ethanol-soluble fractions containing the secondary metabolites were called AG-SBH for the hydroalcoholic extract and AG-SBA for the aqueous extract. To simplify the samples they were submitted to liquid-liquid partitioning with solvents of different polarities, resulting in seven different fractions (AG-SBH-Aq and AG-SBA-Aq, AG-SBH-BuOH and AG-SBA-BuOH, AG- SBHAcEt and AG-SBA-AcEt and AG-SBH-CHCl3), which were analyzed by high performance liquid chromatography and mass spectrometry. A total of 32 compounds were found in AGSBH and AGSBA, of which 22 were identified: theobromine, chlorogenic acid, benzoic acid, arenarioside, verbascoside, hofmaniacetone, rutin, p-coumaric acid, ferulic acid, campferol/luteolin diglycoside, 5-hydroxy-7,4-dimethoxypigenin, luteolin, genkwanina, guaiol, bisabolol, spathulenol, zeaxanthin, lupeol acetate, betulin, ursolic acid and oleanic acid. An unprecedented component to the plant was also identified, the campferol/luteolin diglycoside flavonoid. In addition, some compounds could be quantified by external standardization. The rutin flavonoid was found to be the major compound for the plant, having about 61.1 µg/mg dry weight, which may be linked to many of the medicinal activities attributed to Aloysia gratissima, mainly antioxidant and neuroprotective; followed by the phenolic pcoumaric acid at 15.2 µg/mg and the theobromine alkaloid at 9.21 µg/mg. This quantification refers to the AG-SBH extract, where in AG-SBA the order of concentration was the same, but the values found were considerably lower. Such data corroborate previous research and legitimize future research on the compounds of this important medicinal plant.