RESUMO -Os óleos essenciais apresentam possibilidade de serem empregados nas indústrias de alimentos, bebidas, produtos de higiene pessoal e cosméticos para evitar ou reduzir a deterioração lipídica e a contaminação por micro-organismos. ABSTRACT -Essential oils can be employed in the food, drinks, toiletry and cosmetics industries to prevent or reduce lipid deterioration and contamination by microorganisms. The aim of this work was to evaluate the functional antimicrobial and antioxidant properties of essential oils of fresh leaves from Coniza bonariensis, Parthenium hysterophorus, Tithonia diversifolia, Ambrosia polystachya, Hedychium coronarium and Baccharis dracunculifolia, extracted by hydrodistillation. The methodologies used for assessing antioxidant potential were consumption of the DPPH radical and oxidation inhibition of the -carotene/linoleic acid system. Sensitivity of the bacteria Salmonella cholerasuis, Listeria monocytogenes, Staphylococcus aureus and Escherichia coli to the essential oils was determined using the agar-well diffusion method. The essential oils were noteworthy for their high terpenoid content. None of the essential oils assessed by DPPH radical sequestration presented significant IC 50 . Using -carotene/linoleic acid methodology, the essential oils of T. diversifolia and H. coronarium showed no significant activity, and C. bonariensis, P. hysterophorus, A. polystachya and B. dracunculifolia showed IC 50 greater than the highest concentration evaluated. The essential oils of C. bonariensis, T. diversifolia, H. coronarium and B. dracunculifolia displayed antibacterial activity for gram-negative and grampositive bacteria, with the exception of the volatile oil of P. hysterophorus, which did not inhibit growth in any of the bacterial strains tested. The essential oil of A. polystachya displayed antibacterial activity only for strains of S. aureus.

The extraction of essential oils was performed by using the technique of hydrodistillation modified Clevenger apparatus, identification and quantification of the constituents was achieved by Gas Chromatography coupled to Mass Spectrometry, and Gas Chromatography equipped with a flame ionization detector. Assessment of allelopathic activity was evaluated with the use of the method that assesses the direct contact of essential oils on germination and vigor of lettuce seeds. The major constituents that characterize the essential oil from the flowers of Callistemon viminalis were 1, 8-cineole, α-pinene and limonene at concentrations of 66.9%, 16.0% and 10.0%, respectively. The essential oil presented allelopathic activity at intensities that varied proportionately to the concentration of the essential oil, with a reduction in the percentage of germination and the germination speed index (GSI) of lettuce seeds and in the dry mass and length of shoots and roots of lettuce seedlings.

ABSTRACT

BackgroundThe search for new inhibitors of snake venom toxins is essential to complement or even replace traditional antivenom therapy, especially in relation to compounds that neutralize the local effects of envenomations. Besides their possible use as alternative to traditional antivenom therapy, some plant species possess bioactive secondary metabolites including essential oils, which can be extracted from weeds that are considered substantial problems for agriculture, such as Hedychium coronarium.MethodsThe essential oils of leaves and rhizomes from H. coronarium were extracted by hydrodistillation, and their potential inhibitory effects on the coagulant and fibrinogenolytic activities induced by the venoms of Lachesis muta, Bothrops atrox and Bothrops moojeni were analyzed. Citrated human plasma was used to evaluate the clotting time whereas changes in fibrinogen molecules were visualized by electrophoresis in polyacrylamide gel. The experimental design used for testing coagulation inhibition was randomized in a 3 × 2 factorial arrangement (concentration × essential oils), with three replications. The essential oils were compared since they were extracted from different organs of the same botanical species, H. coronarium.ResultsThe results suggest that the oils interact with venom proteases and plasma constituents, since all oils evaluated, when previously incubated with venoms, were able to inhibit the clotting effect, with less inhibition when oils and plasma were preincubated prior to the addition of venoms.ConclusionsThus, after extensive characterization of their pharmacological and toxicological effects, the essential oils can be used as an alternative to complement serum therapy, especially considering that these plant metabolites generally do not require specific formulations and may be used topically immediately after extraction.

<p align = "justify">Óleos essenciais extraídos de ervas e especiarias empregadas para realçar as características sensoriais dos alimentos têm sido testados quanto às características antioxidantes, ganhando maior destaque devido à sua posição como produto natural, sua grande aceitação pelos consumidores, seu potencial de uso multifuncional e aos riscos potenciais dos aditivos sintéticos. Dessa forma, o presente trabalho teve como objetivos analisar a composição química de óleos essenciais extraídos de folhas frescas de tomilho, capim-limão, alfavaca e manjericão, suas atividades antioxidantes pelas metodologias do sequestro dos radicais DPPH e da inibição da oxidação do sistema do β-caroteno/ácido linoleico. Foram avaliados os potenciais antioxidantes dos padrões dos constituintes majoritários dos referidos óleos essenciais timol, citral, eugenol e linalol, respectivamente, usando-se como controles positivos os antioxidantes sintéticos ácido ascórbico, BHA e BHT. Adicionalmente, objetivou-se correlacionar as composições químicas e concentração de 50% de inibição (CI50) dos referidos óleos essenciais por meio da análise de agrupamentos hierárquicos (HCA). Os constituintes majoritários presentes nos óleos essenciais das folhas frescas de tomilho, capim-limão, alfavaca e manjericão são o timol, p-cimeno e γ-terpineno; o geranial, neral e mirceno; eugenol, (γ)-muuruleno e (cis)-β-ocimeno; cineol, linalol e cânfora, respectivamente. As amostras com atividades antioxidantes mais expressivas são o eugenol e o óleo essencial de alfavaca. Utilizando-se a HCA, observa-se que os óleos essenciais e seus respectivos padrões se agrupam devido à similaridade quanto às quantidades de fenilpropanoides e monoterpenos. Este estudo pode ser importante para encontrar e analisar novos compostos de origem natural que permitam inibir a oxidação.</p>