F. A. Pimentel

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.

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.

Caracterização e avaliação de acilaçúcar sintético no comportamento da mosca-branca Bemisia tabaci (Gennadius, 1886) biótipo B (Hemíptera: Aleyrodidae) em tomateiro

O cultivo de tomate e uma atividade de destaque no Brasil em termos de producao e consumo e os estados de Goias, Sao Paulo e Minas Gerais sao os principais produtores. Visando a desenvolver novos compostos com funcao inseticida, este trabalho foi desenvolvido com o objetivo de sintetizar acilacucares, aleloquimico presente nas folhas que conferem resistencia natural ao tomateiro Lycopersicon pennellii e avaliar seus efeitos no comportamento da mosca-branca. O delineamento utilizado foi o inteiramente casualizado, com cinco tratamentos e cinco repeticoes. Os ensaios consistiram dos seguintes tratamentos: plantas de tomate cv. Santa Clara pulverizadas com agua pura (testemunha); plantas de tomate cv. Santa Clara pulverizadas com acilacucar 01 (sintetizado a partir de sacarose); plantas de tomate cv. Santa Clara pulverizadas com acilacucar 02 (sintetizado a partir da glicose com cloreto de zinco como catalisador); plantas de tomate cv. Santa Clara pulverizadas com acilacucar 03 (sintetizado a partir da glicose com acetato de sodio como catalisador) e plantas de tomate Lycopersicon pennellii pulverizadas com agua pura. A concentracao do composto utilizada foi de 0,05%. Os resultados obtidos mostraram que o acilacucar 03 reduz a oviposicao do inseto no tomateiro. Todavia, se fazem necessarios estudos mais detalhados para se avaliar melhor a acao desse composto sobre a mosca-branca.

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.

Influência da temperatura de secagem sobre o rendimento e a composição química do óleo essencial de Tanaecium nocturnum (barb. Rodr.) bur. & K. Shum

The yields and chemical compositions of the essential oils obtained by steam distillation of the fresh and dried (30 and 40 oC) leaves, stems and roots of Tanaecium nocturnum are reported. The identification and quantification of the volatile constituents were accomplished by GC/MS and GC/FID, respectively. The essential oils obtained from the various parts of the plant were constituted mainly of benzaldehyde. Large losses and variations in the quantities of the components during the drying process were observed. The presence of mandelonitrile in higher concentration in the stem and roots indicates that this species produces cyanogenic glycosides.