Estudo químico e avaliação da atividade antioxidante do óleo essencial e extrato das folhas de Syzygium cumini (L.) Skeels

Abstract

Syzygium cumini (L.) Skeels belongs to the Myrtaceae family and sub Myrtoideae family. Several studies have shown pharmacological activity S. cumini such as antidiabetic, anti-inflammatory, antimicrobial, antioxidant. Results found in the literature reports the presence of phenolic compounds in this species. The leaves of S. cumini were collected from a single plant every two months during the period from 08/2013 to 08/2014 to obtain essential oils by hydrodistillation of fresh and dried leaves. The extract obtained was refluxed with 70% ethanol. The crude extract was fractionated by liquid-liquid partition obtaining hexane fraction (FHAZ), chloroform fraction (FCAZ), ethyl acetate fraction (FAAZ), butanol fraction (FBAZ) and hydroalcoholic fraction (FHAAZ). FAAZ was fractionated by chromatography high performance against current (HPCCC) HEMWats using solvent systems (hexane: ethyl acetate: methanol: water) and EBWats (ethyl acetate: butanol: water). The yield of essential oil of fresh leaves was higher in the period that the plant was in inflorescence stage and a decrease occurred shortly after the end of season fruit production and the following samples a slight stabilization in revenue. The result of the influence of temperature essential oil showed a yield increase of sheets S. cumini periods in higher temperatures. Proceeds essential oils from dried leaves were always higher than the values found in the fresh leaves. It was also observed change in concentration of secondary metabolites, e.g., α- pinene in June / 2014 dry leaves 46.34% and 39.40% fresh leaves. In relation to the antioxidant activity assays, activity was observed for all tested against the fractions and extract the radical DPPH (2,2-diphenyl-picryl-hydrazyl). The IC50 value of FAAZ fractions, FBAZ and FHAAZ were close to the standard of gallic acid. The result of IC50 fraction FAAZ 9.40 ± 0.40 μg / mL was lower than those found in the literature. The IC50 values obtained for the subfractions were HPCCC: FAAZ81 22.13 ± 1.12 μg / mL, FAAZ82 8.60 ± 0.26 μg / mL, FAAZ83 14.17 ± 0.60 μg / ml and FAAZ84 2.87 ± 1.25 μg / mL. This was shown by HPLC / MS the presence of substances in the fraction 36 in ethyl acetate (FAAZ). 19 first being identified as belonging to the class of flavonoids and other phenolic compounds, with antioxidant activity against DPPH radical.