Atividade antioxidante de óleos essenciais de espécies de Croton do nordeste do Brasil

Three Croton species, C. zenhtneri, C. nepetaefolius and C. argyrophylloides, were collected at two different times, 6:00 and 13:00 h, their essential oils were extracted by steam distillation and analyzed by gas Chromatography / Mass Spectrometry. The percentage yield of oil constituents changes along the day. The oils were submitted to the antioxidant test thiobarbituric acid reactive species, using BHT and a-tocoferol as the reference compounds. All oils exhibited good antioxidant activities. In general, C. zenhtneri and C. argyrophylloides essential oils showed higher antioxidant activity than C. nepetaefolius.

O emprego da termogravimetria para determinar a energia de ativação do processo de combustão de óleos combustíveis

Activation energy (Ea) is a parameter that can be applied to make predictions about the quality of oils to be used in an ICO engine. In this study, Ea was determined by thermogravimetry following two different procedures: ASTM E 1641 and Model-free kinetics. The energies were calculated in the low temperature oxidation (LTO) region for three Brazilian fuel oils (denominated A, B and C) and the results were equal using both methods: 43 kJ mol-1 (alpha=0.1 to 0.9) for oil A, 48 kJ mol-1 (alpha=0.1 to 0.5) and 65 kJ mol-1 (alpha=0.5 to 0.9) for oil B, and 58 kJ mol-1 (alpha=0.1 to 0.5) and 65 kJ mol-1 (alpha=0.5 to 0.9) for oil C. It was concluded that, among the oils studied, sample A was potentially the best option concerning the behavior in the LTO region.

Determinação de contaminantes em óleos lubrificantes usados e em esgotos contaminados por esses lubrificantes

A simple and reliable ashing procedure is proposed for the preparation of used lubricating oil samples for the determination of Zn, Fe, Pb, Ni and Cu by the flame atomic absorption spectrometry technique. Sulphanilic acid was added to oil samples, the mixture coked and the coke ashed at 550 ºC. The solutions of the ash were analysed by flame AAS for these metals. The quantification limits were 38.250 µg g-1 for Zn, 4.550 µg g-1 for Fe, 1.562 µg g-1 for Pb, 1.450 µg g-1 for Ni, and 0.439 µg g-1 for Cu. The determinations, in lubricating oil, showed good precision and accuracy with recoveries between 90 and 110 %, indicating a negligible matrix effect in the experiments using addition of analyte, with relative standard deviation lower than 5%. The results for analysis of wastewater contamined by theses lubricants showed a very high relative standard deviation.

Atividade acaricida dos óleos essencias de folhas e frutos de Xylopia sericea sobre o ácaro rajado (Tetranychus urticae Koch)

The essential oils of the leaves and fruits obtained by hydrodistillation of Xylopia sericea, collected in the restinga area of Pernambuco, were analyzed by GC (HP 5890 SERIES II) and GC/MS (HP 5890B SERIES II/ MSD 5971). A major part of the volatile components identified in the oils of fruits and leaves were monoterpenes and sesquiterpenes. Cubenol (57.43%) and alpha-epi-muurolol (26.09%) were the main compounds found in the leaves, whereas beta-pinene (45.59%) and alpha-pinene (17.18%) were the fruits major components. The acaricidal activity of the essential oils was evaluated for Tetranychus urticae. The oil of the leaves was more active than that of the fruits showing an LC50 value of 4.08 µL/L of air for a 72 h period.

Composição química dos óleos essenciais das folhas de seis espécies do gênero Baccharis de "Campos de Altitude" da mata atlântica paulista

The essential oils from the leaves of six species of the Baccharis genus (B. dracunculifolia, B. microdonta, B. regnelli, B. schultzii, B. trimera, and B. uncinella), collected in the "Campos de Altitude" of the Atlantic Forest (SP), were extracted using hydrodistillation procedures and analyzed by GC and GC/MS. There was a predominance of sesquiterpenes in all studied oils as b-elemene in B. dracunculifolia and B. regnelli, a-humulene in B. trimera, g-gurjunene in B. schultzii, bicyclogermacrene in B. regnelli, d-cadinene in B. regnelli and B. uncinella, spathulenol in B. schultzii, caryophyllene oxide in B. microdonta and guaiol in B. uncinella. However, a high amount of monoterpenes was also observed in B. uncinella (a-pinene), B. regnelli (d-car-3-ene) and B. schultzii (limonene). The chemical compounds of the essential oils of B. schultzii, B. regnelli and B. microdonta are described for the first time in this work.

Perfil de ácidos graxos e avaliação da alteração em óleos de fritura

The present study had the purpose of evaluating the profile of fatty acids and the total alteration of cottonseed, sunflower and palm oils brought about during discontinued frying processes of cassava frozen chips. An increase in the percentage of saturated fatty acids and a decrease in polyunsaturated fatty acids was observed, regardless of the type of oil used. With regard to the oil's global alteration, the results showed that palm oil, the most saturated one, underwent less alteration. However, none of the oils presented total polar compound values above the limits prescribed.

Quantificação de TBHQ (terc butil hidroquinona) e avaliação da estabilidade oxidativa em óleos de girassol comerciais

Sunflower oil is one of the vegetable oils most susceptible to oxidative reaction. Therefore the presence of natural (tocopherol) and/or synthetic (TBHQ) antioxidants is a prerequisite to secure the stability of this oil during its shelf life, especially with the increased use of PET packaging. On determining the total tocopherol content in 10 samples of deodorized sunflower oils, high losses in total tocopherol during deodorization were identified. In order to facilitate researche involving oxidative stability of vegetable oils, a method for isolated quantification of TBHQ using the isocratic elution system was developed.

Composição e atividade antibacteriana dos óleos essenciais de Senecio crassiflorus var. crassiflorus

The essential oils of leaves, aerial and underground stems of Senecio crassiflorus var. crassiflorus were extracted by hydrodistillation and their analyses were performed by GC/MS. Qualitative and quantitative differences have been found between the analyzed parts. The main compounds of the essentials oils of the leaves were found to be oxygenated sesquiterpenes, while the oils from the aerial and underground stems showed sesquiterpene hydrocarbons as major constituents. Furthermore, the essential oils were tested against Staphylocccus aureus, Escherichia coli, Pseudomonas aeruginosa and Bacillus cereus. The essential oil of the leaves was shown to be the most active.

Estudo comparativo de técnicas de screening para avaliação da atividade anti-bacteriana de extratos brutos de espécies vegetais e de substâncias puras

In this work, the effectiveness of four screening techniques (three techniques of the diffusion method and one microdilution broth method) were compared. Evaluated were the ethanolic and dichloromethanic extracts of Miconia rubiginosa (Melastomataceae) against six standard bacteria (ATCC). The results showed statistical disagreement among the three diffusion techniques. Among the diffusion techniques, the well technique displayed the best result. However the microdilution broth method demonstrated to be the most adequate method to evaluate the antibacterial activity of plant crude extracts and pure compounds when compared to the other methodologies.

Óleos essenciais no Brasil: aspectos gerais, desenvolvimento e perspectivas

Essential oils are extracted by steam distillation of plants or cold pressing of citrus fruit pericarp. They are used in food, cosmetic, personal care and pharmaceutical industries. In Brazil, oils from orange and related products contribute to near 97% to the positive commercial performance of the sector. Predatory exploitation and the availability of new sources of raw materials, with more attracting prices, changed the paradigm. Prospective studies, sustainable use of Brazilian biodiversity, domestication of exotic species with commercial relevance, the use of breeding techniques and the development of new applications for essential oils are thematic lines, usually multidisciplinary, which have been prompting the expansion of the research on essential oils. This paper presents an analysis on essential oils balance trade from 2005 to 2008 and some historical data on research and production of essential oils in Brazil.

Fontes vegetais naturais de antioxidantes

Growing knowledge on the health-promoting impact of antioxidants in everyday foods, combined with the assumption that a number of common synthetic preservatives may have hazardous side effects has led to increased investigations in the field of natural antioxidants, principally those found in plants. Food industries normally discard plant residues that could benefit the human health and diminish undesirable environmental impact. Once estimated the content of antioxidants in these residues, advantageous economical and social alternatives to the discard are possible, for example, their use for preparation of nutraceuticals to be offered to low-income populations. We present here a broad, although not complete, account of the continuously growing knowledge on the antioxidant capacity of whole fruits, seeds and peels, cereals, vegetal oils and aromatic plants, at several physical forms, as well as a description of the usual methods for evaluating their antioxidant capacity and examples of agroindustrial processes that could be harnessed for the production of antioxidant supplement food, along with research perspectives in the area.

Biocombustíveis a partir de óleos e gorduras: desafios tecnológicos para viabilizá-los

Periodically, during petroleum shortage, fatty acids and their derivatives have been used as alternative fuels to those derived from petroleum. Different approaches have been proposed, including the use of neat fats and oils or their derivatives. Indeed, the utilization of biodiesel produced by alcoholysis of triacilglycerides or esterification of fatty acids, or hydrocarbons obtained from cracking of fatty materials were studied and used in several countries. Increasing concerns about energy security and climate changes have lead several countries, including Brazil, to start up biofuels programs. Different technologies are currently being developed in order to produce biofuels with economical feasibility. In this work are discussed alternative fatty raw-materials and processing technologies that are currently being studied in order to produce fuels suitable to sustainable substitute diesel fuel.

Composição química de óleos essenciais de espécies de Aniba e Licaria e suas atividades antioxidante e antiagregante plaquetária

Leaves and stems from Aniba panurensis (Meisn.) Mez, Aniba rosaeodora Ducke and Licaria martiniana (Mez) Kosterm. were collected in the Reserva Florestal Adolpho Ducke-AM and their essential oils were obtained by hydrodistillation procedures. The oils were analyzed by GC-FID and GC-MS resulting on fifty and six compounds being identified. The major components were linalool in A. rosaeodora, and β-caryophyllene in A. panurensis and L. martiniana. At qualitative assays the oils showed antioxidant and antiplatelet activities, but only weak activities were found at quantitative spectrometric assays.

Óleos essenciais das folhas de Vernonia Remotiflora e Vernonia Brasiliana: composição química e atividade biológica

The chemical composition of the essential oils, obtained by hidrodistillation, from leaves of two Vernonia species (V. remotiflora and V. brasiliana), was determined by GC-FID and GC-MS. Both essential oils were predominantly constituted by sesquiterpenes (92.0 - 93.4%). The main constituents of the oil from V. brasilana were (E)-caryophyllene (36.7%), germacrene D (35.5%), and α-humulene (11.7%), while (E)-caryophyllene (42.2%) and bicyclogermacrene (20.0%) were the major ones in the oil from V. remotiflora. Although with moderate activity both oils showed acetylcholinesterase and antibacterial activities.

Determinação de metais em óleos lubrificantes, provenientes de motores de ônibus urbano, utilizando a FAAS

This work proposed a procedure to examine ashes produced in burning lubricating oils used in public transportation, in Teresina PI. Sulphanilic acid was added to the oil samples, which were burned at 550 °C for three hours and 650 °C for two hours. The ash solutions were analyzed by FAAS and there were significant differences in the metal contents of the waste oil produced from normal car service. The quantification limits in μg g-1 were 5.9 (Fe), 4.4 (Pb), 1.7 (Ni), 2.1 (Cu), and 1.2 (Zn). The results showed positive accuracy and precision with recoveries between 88 and 108%, and RSD lower than 10%.