Juliana de Andrade

Atividades antioxidante e fungitóxica do óleo essencial de capim-limão e do citral

Tendo em vista a importância dos oleos essenciais, objetivou-se, com este trabalho, avaliar a atividade antioxidante e os efeitos fungitoxicos do oleo essencial de capim-limao e do seu constituinte majoritario citral sobre a inibicao micelial dos fitopatogenos Fusarium oxysporum cubense, Colletotrichum gloeosporioides, Bipolaris sp. e Alternaria alternata. A atividade antioxidante foi realizada, empregando os metodos de reducao do radical livre DPPH e o ensaio de oxidacao do sistema b-caroteno/acido linoleico. Para cada metodologia, utilizou-se o delineamento inteiramente casualizado em esquema fatorial de 4 x 5, sendo quatro compostos (oleo essencial, citral, timol e α-tocoferol) e cinco concentracoes (5; 10; 25; 50 e 100 µg L-1), com tres repeticoes Os ensaios para verificacao das atividades fungitoxicas foram realizados aplicando o teste de fumigacao in vitro sobre a inibicao micelial dos fungos fitopatogenicos estudados. Os tratamentos foram dispostos de forma inteiramente casualizada, com tres repeticoes e em esquema fatorial com arranjo variavel entre os fitopatogenos. O oleo essencial e o citral apresentaram pequena atividade antioxidante perante a metodologia que avalia a reducao do radical estavel DPPH, no entanto, perante a metodologia que emprega o sistema emulsificado β-caroteno/acido linoleico estes compostos apresentaram atividades antioxidantes significativas. Nas atividades fungitoxicas, o oleo essencial e o citral apresentaram uma maior atividade sobre o fitopatogeno Alternaria alternata. Em relacao aos valores de IC50 os menores valores apresentados pelo oleo essencial (75,83 µg mL-1) e pelo citral (58,24 µg mL-1) foram sobre o Bipolaris sp. O citral causou as maiores inibicoes miceliais, para todos os fitopatogenos.

Chemical Composition and Antioxidant Activity of Essential Oils from Cinnamodendron dinisii Schwacke and Siparuna guianensis Aublet

The objectives of this study were to chemically characterize and evaluate the antioxidant activity of essential oils Cinnamodendron dinisii Schwacke (pepper) and Siparuna guianensis Aublet (negramina). The essential oil was isolated by hydrodistillation using a Clevenger modified apparatus, and the identification and quantification of constituents, through GC/MS and GC-FID analysis. The antioxidant activity was evaluated using β-carotene/linoleic acid system and the DPPH radical sequestering method. In chromatographic analysis, the majority constituents found in the essential oil of C. dinisii were bicyclic monoterpenes, α-pinene (35.41%), β-pinene (17.81%), sabinene (12.01%) and sesquiterpene bicyclogermacrene (7.59%). In the essential oil of the fresh leaves of Siparuna guianensis Aublet, acyclic monoterpene, β-myrcene (13.14%), and sesquiterpenes, germacrene-D (8.68%) and bicyclogermacrene (16.71%) were identified. The antioxidant activity was low by the β-carotene/linoleic acid test and was not evidenced by the DPPH test, for both oils evaluated.

Linalool, a Piper aduncum essential oil component, has selective activity against Trypanosoma cruzi trypomastigote forms at 4°C

BACKGROUND Recent studies showed that essential oils from different pepper species (Piper spp.) have promising leishmanicidal and trypanocidal activities. OBJECTIVES In search for natural compounds against Trypanosoma cruzi, different forms of the parasite were incubated for 24 h at 28ºC or 4ºC with Piper aduncum essential oil (PaEO) or its main constituents linalool and nerolidol. METHODS PaEO chemical composition was obtained by GC-MS. Drug activity assays were based on cell counting, MTT data or infection index values. The effect of PaEO on the T. cruzi cell cycle and mitochondrial membrane potential was evaluated by flow cytometry. FINDINGS PaEO was effective against cell-derived (IC50/24 h: 2.8 μg/mL) and metacyclic (IC50/24 h: 12.1 μg/mL) trypomastigotes, as well as intracellular amastigotes (IC50/24 h: 9 μg/mL). At 4ºC - the temperature of red blood cells (RBCs) storage in blood banks - cell-derived trypomastigotes were more sensitive to PaEO (IC50/24 h = 3.8 μg/mL) than to gentian violet (IC50/24 h = 24.7 mg/mL). Cytotoxicity assays using Vero cells (37ºC) and RBCs (4ºC) showed that PaEO has increased selectivity for cell-derived trypomastigotes. Flow cytometry analysis showed that PaEO does not affect the cell cycle of T. cruzi epimastigotes, but decreases their mitochondrial membrane potential. GC-MS data identified nerolidol and linalool as major components of PaEO, and linalool had trypanocidal effect (IC50/24 h: 306 ng/mL) at 4ºC. MAIN CONCLUSION The trypanocidal effect of PaEO is likely due to the presence of linalool, which may represent an interesting candidate for use in the treatment of potentially contaminated RBCs bags at low temperature.

Chemical analyses of the essential oils from leaves of Mikania glauca Mart. ex Baker

The essential oils obtained by hydrodistillation of two samples of fresh Mikania glauca leaves collected in different periods were analyzed by gas chromatography (GC) and by GC–mass spectrometry (GC–MS). Twenty compounds, representing 99% of the total oil composition, were identified and quantified in sample 1, while forty-five compounds, also representing 99% of the total oil composition, were identified in sample 2. The essential oils from the fresh leaves of both samples were rich in the terpenes. In sample 1 and 2, respectively, α-pinene (27% and 26%), β-pinene (22% and 36%), myrcene (24% and 18%), β-caryophyllene (9% and 6%) and bicyclogermacrene (8% and 4%) were the principal constituents. This demonstrated the predominance of monoterpene hydrocarbons in the essential oil of M. glauca and the influence of the collection period on the concentrations of the components.

Óleo essencial de Baccharis tridentata Vahl: composição química, atividade antioxidante e fungitóxica, e caracterização morfológica das estruturas secretoras por microscopia eletrônica de varredura

This study aimed to evaluate the chemical composition and the antioxidant and fungitoxic activities of Baccharis tridentata essential oil, as well as to study the morphology of its secretory structures present on the leaf surface by scanning electron microscopy (SEM). The essential oil was extracted by hydrodistillation; the quantitative and qualitative analyses were performed on a gas chromatograph equipped with a flame ionization detector (FID) and coupled to a mass spectrometer, respectively. The antioxidant activity was determined by the methods of reduction of the DPPH stable radical and oxidation of the β-carotene/linoleic acid system. Fungitoxic activities were assessed by the in vitro bioanalytical test on the inhibition of the mycelial growth of the plant pathogens Fusarium oxysporum, Colletotrichum gloeosporioides and Rhizoctonia solani. The chemical composition revealed the presence of 28 compounds, with α-thujene (22.93%) as the major constituent. No antioxidant activity was observed in the tests used; however, there was fungitoxic activity against the mycelial growth of plant pathogens. Leaf surface studies by SEM revealed the presence of glandular trichomes on both abaxial and adaxial surfaces.

Chemical characterisation and allelopathic potential of essential oils from leaves and rhizomes of white ginger

Essential oils have the potential to be used as bioherbicides, and possess the advantage of their biodegradability, high structural diversity and reduced natural resistance to weeds. The essential oils of the leaves and rhizomes of Hedychium coronarium, an exotic invasive plant adapted to different regions of Brazil, were extracted by hydrodistillation and characterised chemically by Gas-Liquid Chromatography and Gas-Liquid Chromatography/Mass Spectrometry. Allelopathic activity was determined using methodologies that evaluate the effects of volatility and direct contact on seed germination and seedling vigour in the lettuce. The major constituents of the essential oil from the leaves were β-pinene (46.9%), α-pinene (19.2%) and β-caryophyllene (13.2%) and from the rhizomes, β-pinene (41.5%), 1.8-cineole (23.6%) and α-pinene (13.1%). When analysing the volatile effects of the essential oils, it was seen that their concentration did not affect seedling first germination count or total germination. The essential oil from the rhizomes was more effective than the essential oil from the leaves in reducing seedling response for SGI, dry weight, and length of the roots and shoots. When evaluating the effect of direct contact with the essential oils, it was seen that both oils reduced the response of all the variables under evaluation, and that in addition, the oil from the rhizomes caused greater reductions than that from the leaves, again for all variables. These results can be attributed to the higher levels of monoterpenes present in the essential oil from the rhizomes, mainly the presence of 1.8-cineole.