Estudo fitoquímico e atividades biológicas de Eperua duckeana e Eperua glabriflora (Fabaceae)

Abstract

Eperua is a genus of the Fabaceae-Caesalpinioideae, endemic to the Central Amazon. The oilresin of E. oleifera, E. purpurea e E. falcata is used in folk medicine in order analogous to “copaiba”, as a healing agent antifungal and bactericide. In general, two class substances have been isolated from this species: terpenes and flavonoids. Despite the species E. glabriflora and E. duckeana are common in the Amazon, have never been studied chemically and pharmacologically. This study aimed to evaluate the chemical composition of extracts of bark of trunk and leaves and to determine the antioxidant, antibacterial, antifungal, antiprotozoal and cytotoxic activity against tumor cells, and analyzing the chemical composition of essential oils from leaves and stems of these species. The plant material was collected in Ducke Reserve near Manaus and the bark and leaves were dried at room temperature and later crushed. The extracts were prepared by maceration with solvent in order of increasing polarity (hexane, ethyl acetate and methanol) were obtained twelve crude extracts. The non-polar extracts of bark of trunk were analyzed by gas chromatography coupled with mass spectrometry (GC-MS) and flame ionization detector (GC-FID). It was identified fourteen substances among them: six fatty acids (hexadecanoic acid, 9,12-octadecadienoic acid, 9- octadecenoic acid, octadecanoic acid, tetracosanoic acid and hexacosanoic acid); four diterpene acids (cativic acid, 3-hydroxylabd-7,13-dien-15-oic acid, 3-cleroden-15-oic acid and one isomer); one hydrocarbon (squalene); one vitamin (α-tocopherol); and two sterols (stigmasterol and β-sitosterol). The latter two substances were isolated in mixture and identified by spectrometric methods. From ethyl acetate extract of bark of trunk E.glabriflora was isolated from 3-O-glycoside-flavanonol, engeletin also present in the extract of E. duckeana, but in lower concentration. Other flavonoid was isolated from M+ 476 u.ma. Essential oils were obtained by hydrodistillation in Clevenger apparatus changed during 4h, then dried with sodium sulfate and analyzed by GC-FID and GC-MS. We identified 35 constituents in essential oils, and the β-caryophyllene and germacrene D the major constituents. Essential oils from leaves and stems showed cytotoxic activity against tumor cell lines of breast cancer (MDA/MB-435), colon (HCT8) and central nervous system (SKF-295) with inhibitions of growth of approximately 100%. The extracts tested showed weak or no trypanosoma cruzi or leishmania activity and antibacterial and antifungal activity, except the hexane extract of the bark of E. glabriflora that showed significant activity against grampositive bacterium Bacillus subtilis (MIC = 62.5 μg /mL). With respect to antioxidant potential, the highest activity of free radical sequestration was presented by the extracts in ethyl acetate and methanol of bark of trunk (IC50 10.5 -17.8 mg / mL) in both species. The results of this study contribute to the knowledge of chemical and biological of two species from Amazonian biodiversity.