Luiz Gustavo de Lima Guimarães

Anti-proliferative effect of the essential oil of Cymbopogon citratus (DC) Stapf (lemongrass) on intracellular amastigotes, bloodstream trypomastigotes and culture epimastigotes of Trypanosoma cruzi (Protozoa: Kinetoplastida)

This study analyses the anti-proliferative effect of lemongrass essential oil and its main constituent (citral) on all 3 evolutive forms of Trypanosoma cruzi. Steam distillation was used to obtain lemongrass essential oil, with chemical composition determined by gas chromatography (GC) and GC coupled to mass spectrometry (GC-MS). The IC50/24 h (concentration that reduced the parasite population by 50%) of the oil and of citral upon T. cruzi was determined by cell counting in a Neubauer chamber, while morphological alterations were visualized by scanning and transmission electron microscopy. Treatment with the essential oil resulted in epimastigote growth inhibition with IC50=126.5 microg/ml, while the IC50 for trypomastigote lysis was 15.5 microg/ml. The IC50/48 h for the Association Index (% macrophage infection x number of amastigotes per cell) was 5.1 microg/ml, with a strong inhibition of intracellular amastigote proliferation. Ultrastructural analysis demonstrated cytoplasmic and nuclear extraction, while the plasma membrane remained morphologically preserved. Our data show that lemongrass essential oil is effective against T. cruzi trypomastigotes and amastigotes, and that its main component, citral, is responsible for the trypanocidal activity. These results indicate that essential oils can be promising anti-parasitic agents, opening perspectives to the discovery of more effective drugs of vegetal origin for treatment of parasitic diseases. However, additional cytotoxicity experiments on different cell lines and tests in a T. cruzi-mouse model are needed to support these data.

Caracterização química e efeito inibitório de óleos essenciais sobre o crescimento de Staphylococcus aureus e Escherichia coli

Objetivou-se avaliar o efeito inibitorio dos oleos essenciais de Cymbopogon citratus (capim-limao), Origanum vulgare (oregano) e Syzygium aromaticum (cravo-da-india); os experimentos foram realizados com as bacterias Staphylococcus aureus e Escherichia coli, importantes patogenos causadores de contaminacoes em queijos e outros alimentos. Para quantificacao e identificacao dos constituintes quimicos dos oleos, utilizou-se um cromatografo gasoso acoplado a um espectrometro de massa. Os resultados dos testes in vitro, os oleos essenciais de C. citratus, O. vulgare e S. aromaticum promoveram efeito inibitorio sobre as bacterias S. aureus e E. coli, porem o S. aromaticum apresentou melhor formacao de halo de inibicao nas menores concentracoes. Para o efeito sinergistico dos oleos sobre as bacterias nao foram observadas diferencas quando comparados com o efeito individual dos mesmos. Foi possivel verificar que os oleos possuem efeito inibitorio sobre os microrganismos estudados, sendo, portanto uma alternativa no controle microbiologico de alimentos.

Influência da luz e da temperatura sobre a oxidação do óleo essencial de capim-limão (Cymbopogon citratus (D.C.) Stapf)

The identification of the chemical compounds of the essential oil was performed with a gas chromatograph coupled to a mass spectrometer. The oil was left in the presence and absence of light and submitted to different temperatures to evaluate its stability. The yields of the major compounds were evaluated every fifteen days. Citral and myrcene, the major compounds of the essential oil, were degraded over time in both the presence and absence of light, but temperature only influenced the degradation of myrcene.

Chemical composition and fumigant effect of essentialoil of Lippia sidoides Cham. and monoterpenes against Tenebrio molitor (L.) (coleoptera: tenebrionidae)

A composicao quimica do oleo essencial de Lippia sidoides obtido por hidrodestilacao foi caracterizada e quantificada por GC/MS, bem como sua atividade inseticida por teste de fumigacao foi avaliada sobre Tenebrio molitor. Alem disso, a toxicidade dos monoterpenos carvacrol, 1,8-cineol e timol, tambem foi avaliada quando esses compostos foram aplicados isoladamente, ou em misturas binarias (1:1), ou terciarias (1:1:1). O oleo essencial de L. sidoides tem como principais constituintes o carvacrol (31,68%), ρ-cimeno (19,58%), 1,8-cineol (9,26%) e ϒ-terpineno (9,21%), em 21 compostos identificados, sendo 92,53% do total. Ambos os compostos possuem atividade inseticida contra T. molitor, seguindo a ordem de toxicidade: carvacrol > 1,8-cineol > oleo essencial de L. sidoides > timol; sendo suas respectivas CL50 a 24 h de 5,53; 5,71; 8,04 e 14,71 µL/L ar. Quando as diferentes misturas de carvacrol, 1,8-cineol e timol foram avaliadas contra T. molitor, verificou-se o efeito sinergico. Para a mistura de carvacrol:1,8-cineol a CL50 foi de 5,34 µL/L ar; carvacrol:timol de 7,67 µL/L ar; 1,8-cineol:timol de 7,51 µL/L ar e carvacrol:1,8-cineol:timol de 6,34 µL/L ar. Principalmente o monoterpeno timol teve efeito sinergico, aumentando a toxicidade de carvacrol e 1,8-cineol quando em misturas binarias, tais como carvacrol:timol e 1,8-cineol:timol.

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.

Efeito do óleo essencial de pimenta longa (Piper hispidinervum C. DC) e do emulsificante Tween® 80 sobre o crescimento micelial de Alternaria alternata (Fungi: Hyphomycetes)

The object of this work was to evaluate the effectof essential oils from Long-pepper leaves Piper hispidinervum on the mycelial growth of Alternaria alternata and to analyze the influence of emulsifier Tween® 80 concentration in the control of this phytopathogen. The essential oil was obtained by steam stream distillation, using a modified Clevenger apparatus, and the chemical composition was analyzed by gas chromatography coupled to mass spectroscopy GC-MS and GC. For biological tests, the bioanalytical in vitro method was used, observing the growth or inhibition of such phytopathogen in BDA culture media, in the presence of different essential oil concentrations (0, 100, 250, 500, e 1000 mgL -1) under different Tween® 80 concentrations. Factorial scheme with four repetitions, in entirely randomized outline was adopted. The essential oil of Long-pepper inhibited the micellial growth of the A. alternata fungus at all of the concentrations tested. A 100% inhibition at the 1000 mgL -1 concentration was observed, and the percentage of emulsifier (Tween® 80) influenced the fungitoxic activity at the 250 mgL-1 and 500 mgL -1 concentrations of the essential oil.

Potencial fungitóxico do óleo essencial de Piper hispidinervum (pimenta longa) sobre os fungos fitopatogênicos Bipolaris sorokiniana, Fusarium oxysporum e Colletotrichum gloeosporioides

The objective of this study was to evaluate the in vitro antifungal activity of the essential oil of the leaves of Piper hispidinervum against Bipolaris sorokiniana, Fusarium oxysporum and Colletotrichum gloeosporioides. For the biological tests, using the bioanalitic test in vitro the concentrations of 100, 200, 500, 1000, 1500 and 2000 µg.mL-1 the essential oil. This were incorporated into PDA (potato dextrose agar) medium in order to evaluate fungal mycelial growth or inhibition. The statistic design used was completely randomized, with four replicates. In the concentration of 200 µg.mL-1, observed inhibited complete the phytopathogens Bipolaris sorokiniana while the Fusarium oxysporum and Colletotrichum gloeosporioides this is occurred in the concentration of 1000 µg.mL-1.

Ação fungitóxica do óleo essencial de Tanaecium nocturnum (Barb. Rodr.) Bur. e K. Shum sobre o Aspergillus flavus isolado da castanha-do-Brasil (Bertholletia excelsa)

The present work sought to evaluate the fungitoxic activity of the essential oil from fresh Tanaecium nocturnum fresh leaves on Aspergillus flavus isolated from Brazil nuts, using contact and fumigation techniques. The results of bioassays performed up to 10 days of incubation demonstrated that total inhibition of mycelial growth occurred when using the essential oil at concentrations of 782 ppm (contact technique) and 1000 ppm (fumigation technique). In both techniques, the essential oil inhibited the formation of spores at the concentration of 500 ppm. No significant difference in the results presented by the two techniques was observed in the first five days of incubation. After this period, the essential oil showed a reduction in activity at concentrations lower than 1000 ppm in the fumigation test. The fungitoxic activity of the essential oil on the organism studied can be attributed to the presence of benzaldehyde (major component of the essential oil), in combination with other compounds also present in this oil, such as, benzyl alcohol, benzyl benzoate and mandelonitrila.

Antioxidant Potential and its Correlation with the Contents of Phenolic Compounds and Flavonoids of Methanolic Extracts from Different Medicinal Plants

In this study, methanolic extracts of ten species of medicinal plants collected at Gurupi, Tocantins state, Brazil, were subjected to assays of neutralization of ABTS and DPPH radicals, ferric reducing antioxidant power (FRAP), and reducing power to investigate their antioxidant potential. The results revealed that the plants that were investigated exhibited strong antioxidant activities. The species Buchenavia tetraphylla, Buchenavia tomentosa, and Lippia sidoides displayed the highest activities, as well as the largest contents of phenolic compounds and flavonoids. Using Pearson’s correlation coefficient, we could observe correlations between the contents of phenolic compounds and the antioxidant activities in all the assays. On the other hand, we could not observe satisfactory correlations between the flavonoid contents and these activities, which suggest that the phenolic compounds provide the main contributions to the antioxidant potential displayed by the medicinal plant extracts that were studied.

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.