RESUMO A maioria das plantas são resistentes aos diferentes patógenos, e essa resistência pode estar relacionada à existência de compostos fungistáticos naturalmente produzidos. Com o presente trabalho, avaliouse a atividade fungitóxica de óleos essenciais de eucaliptos. Os óleos foram obtidos de folhas dos eucaliptos mediante arraste a vapor de água, utilizando o aparelho de Clevenger modificado. Nos ensaios biológicos, foram empregados os fitopatógenos Fusarium oxysporum, Botrytis cinerea e Bipolaris sorokiniana. O crescimento dos microorganismos na presença de diferentes concentrações de óleo (5, 50 e 500 mg/Kg), usando os meios de cultura BDA (Batata-Dextrose-Ágar) e PCA (Batata-CenouraÁgar), foi avaliado. Nas concentrações de 500 mg/Kg dos óleos, foram observadas inibições significativas no crescimento micelial das espécies fúngicas, após período de 7 dias. No entanto, o óleo essencial de Eucalyptus urophylla foi o que apresentou maior ação fungitóxica, que foi atribuída à presença do composto denominado globulol, ausente no E.camaldulensis e no E. citriodora. TERMOS PARA INDEXAÇÃO:Eucalyptus, óleo essencial, atividade fungitóxica. FUNGITOXIC ACTIVITY EVALUATION OF ESSENTIAL LEAF OILS OF Eucalyptus ON Fusarium oxysporum, Botrytis cinerea AND Bipolaris sorokinianaABSTRACT Most plants are resistant to different pathogens and this resistance may be related to the existence of naturally produced fungistatic components. The present work evaluated the fungitoxic activity of essential oils from three eucalyptus species. The essential oils were obtained from eucalyptus leaves by steam distillation using a modified Clevenger apparatus. The phytopatogens Fusarium oxysporum, Botrytis cinerea and Bipolaris sorokiniana were employed in the biological tests. The growth of fungi in the presence of different concentrations of oil (5, 50, and 500 mg/kg), using BDA (Potato-Dextrose-agar) and PCA (PotatoCarrot-agar) culture media were evaluated. Significant inhibition of the micelial growth of the fungal species was observed at the concentration of 500 mg/kg of oil after a period of seven days. The essential oil of Eucalyptus urophylla showed the greatest fungitoxic activity. This fact was attributed to the presence of the compound globulol, which was absent in the oils obtained from E. camaldulensis and E. citriodora.

Six lignins were used to obtain granular controlled release matrix formulations of the herbicide 2,4-D (2,4-dichlorophenoxyacetic acid). The water insoluble lignins were sourced from sugar cane (Saccharum officinarum) bagasse and Eucalyptus sp. and Pinus sp. woods. Each lignin was characterized by its functional groups and molecular weight distributions. The formulations were prepared by melting the 2,4-D and mixing in the lignins individually and then granulating (to 0.7−1.0 mm) the glassy matrix. Release rates determined in static water were correlated to a diffusion-controlled mechanism according to the square root of time. Principal component regression of the slopes of these lines showed that these depend inversely on the molecular weight and the total and aliphatic hydroxyls of the lignins. For the other functional groups (aromatic hydroxyls, methoxyls, and carbonyls), the higher their contents, the higher the diffusion and release rates. Keywords: Controlled-release; 2,4-D; lignin; chemical structure; release rates

This work describes the chemical composition of the essential oils extracted from fresh leaves of Lippia origanoides Kunth. and Mentha spicata L. and their antioxidant and insecticidal activities. The essential oils were extracted by steam distillation using a modified Clevenger apparatus and subsequently analyzed by gas chromatography-flame ionization detector and gas chromatography-mass spectrometry. The antioxidant activities were determined by the β-carotene-linoleic acid method and by sequestration of the 2,2-diphenyl-1-picryl-hidrazila radical. The concentrations of the essential oils and the synthetic standard, butylated hydroxyltoluene, were 25, 50, 100, 150, 200, 250, 300 and 500 µg mL −1 . Insecticidal activity was analyzed by non-preference with choice and no choice against the aphid Myzus persicae Sulzer. Gas chromatography analysis of the essential oil from Lippia origanoides Kunth. revealed carvacrol (41.51%), p-cymene (18.36%), γ-terpinene (17.03%) and thymol (4.86%) as major constituents, and the essential oil from Mentha spicata L. contained piperitona (81.18%), piperitenone (14.57%) and limonene (1.47%) as the principal components. The essential oils and the standard exhibited dose-dependent antioxidant activities at the concentrations tested. The essential oils were shown to be potential agents in the integrated management of the aphid Myzus persicae Sulzer.

The possibility of commercialization of Moro blood oranges in tropical countries such as Brazil was evaluated to verify whether post-harvest management through storage at low temperatures for a period of 60 days can improve the bioactive properties and quality parameters. Moro blood oranges cultivated in Brazil did not contain significant amounts of anthocyanins at the time of harvesting, but these compounds were activated by post-harvest management through storage at low temperatures (4˚C and 8˚C) for a period of 60 days. The emergence of the anthocyanins in the juices occurred within a few weeks of storage, but the maximum levels were attained after 60 days and at the temperature of 8˚C. Cold storage positively influenced other bioactive compounds such as total phenolic compounds, individual phenolic compounds, β-carotene and the antioxidant activity determined by the sequestration of DPPH free radicals. It did not influence the vitamin C content. In addition, storage significantly altered the color, total acidity and pH of the fruits, but it did not prevent its commercial use. The remaining quality parameters were not influenced. It is possible to commercialize these oranges in Brazil through post-harvest management.

The volatile constituents of the essential oils from leaves from the weed plants Parthenium hysterophorus and Ambrosia polystachya were identified and quantified by GLC-MS and GLC. Allelopathic activities were determined by methods that evaluated the volatile effects and the direct application of these essential oils on the seed germination and seedling vigor of lettuce. We identified 27 compounds in the essential oil from P. hysterophorus, and the main constituents were germacrene-D (35.9%), trans-β-ocimene (8.5%) and β-myrcene (7.6%). In the essential oil from A. polystachya, 40 constituents were identified and the principal compounds were germacrene-D (29.3%), trans-β-ocimene (13.6%) and β-caryophyllene (9.8%). In both methods, the essential oil from A. polystachya presented a greater potential for reducing seed germination and seedling vigor in lettuce than the essential oil from P. hysterophorus, and this activity might be attributed to its higher content of monoterpenes.