Rendimento, composição química e atividade antilisterial de óleos essenciais de espécies de Cymbopogon / Yield, chemical composition and antilisterial activity of essential oils from Cymbopogon species

Objetivou-se determinar o rendimento, a composição química e avaliar a atividade antilisterial dos óleos essenciais de Cymbopogon citratus (DC.) Stapf. (capim-limão) e Cymbopogon nardus (L.) Rendle (capim-citronela), puros e em combinação. A obtenção dos óleos essenciais foi realizada a partir de folhas frescas, empregando-se a técnica de hidrodestilação e utilizando-se aparelho de Clevenger modificado. Os rendimentos foram calculados a partir da massa obtida na extração e da umidade do material vegetal. A análise qualitativa foi realizada por cromatografia em fase gasosa acoplada à espectrometria de massas e a avaliação dos teores dos constituintes químicos por cromatografia em fase gasosa com detector de ionização de chamas. O efeito bacteriostático de diferentes concentrações dos óleos essenciais, puros e em combinação, foi determinado pela técnica de difusão em ágar. As concentrações mínimas inibitórias (CMIs) foram utilizadas na determinação do tempo de ação bactericida. O rendimento, em base seca, foi de 1,39 por cento (v/p) para o óleo essencial de C. citratus e de 2,27 por cento (v/p) para o óleo essencial de C. nardus. Geranial e neral foram os constituintes majoritários do óleo essencial de C. citratus, enquanto, para C. nardus, foram citronelal, geraniol e citronelol. A maioria das concentrações utilizadas mostrou-se efetiva contra Listeria monocytogenes e observaram-se efeitos bactericidas nas CMIs. Óleos essenciais de C. citratus e C. nardus, puros e em combinação, constituem novas alternativas de antibacterianos naturais a serem utilizados no controle de L. monocytogenes na indústria de alimentos.

The aim of this study was to determine the yield and the chemical composition of essential oils from Cymbopogon citratus (DC.) Stapf. (lemongrass) and Cymbopogon nardus (L.) Rendle (citronella), and to evaluate their antilisterial activity when pure and combined. The essential oils were obtained from fresh leaves through hydrodistillation by using a modified Clevenger-type device. Yield was calculated based on the extracted mass and the plant humidity. The qualitative analysis was done by gas chromatography-mass spectrometry and the levels of the chemical components were detected by gas chromatography with flame ionization detector. The bacteriostatic effect of different concentrations of pure and combined essential oils was determined by the agar diffusion technique. Minimum inhibitory concentrations (MICs) were used to determine the time of bactericidal action. The yield was 1.39 percent (v w-1 dry basis) for C. citratus essential oil and 2.27 percent (v w-1) for C. nardus essential oil. Geranial and neral were the major components of C. citratus essential oil, while citronellal, geraniol and citronellol were predominant in C. nardus oil. Most of the used concentrations were efficient against Listeria monocytogenes and bactericidal effects were observed for the MICs. Essential oils of C. citratus and C. nardus, pure and combined, constitute new alternatives of natural antibacterials for the control of L. monocytogenes in the food industry.

Anticorpos contra lentivírus de pequenos ruminantes em caprinos e ovinos em abatedouros do estado de Pernambuco / Small ruminant lentivirus infection in goats and sheep from two abattoirs in Pernambuco State, Brazil

The prevalence of small ruminant lentivirus (SRL) infection was evaluated in goats and sheep in two counties of Pernambuco State, Brasil. Seriological examinations were performed from a total of 672 goats and 325 sheep, one year of age and older, at two abattoirs. Sera were analyzed by agar gel immunodiffusion using Maedi-Visna K-1514 antigens. There were 42 reactive samples (95 percent confidence interval 3.6 percent to 4.9 percent) in both slaughter houses. In São Lourenço da Mata county, 3.2 percent and 4.0 percent of goat and sheep sera were responsive, whereas in Paulista county, 5.1 percent of goat samples and 8.2 percent of sheep were reactive. Thus, the prevalence of small ruminant lentivirus was low in goats and sheep sampled from the region.

Two novel types of bistratified amacrine cells in the chick retina: a Golgi study

1. The correlation between neurotransmitter substances in specific cell types has renewed interest in the morphology of amacrine cells. In this paper we describe the morphology of two types of amacrine cells in Golgi-stained chick retinas. 2. The first cell type was classified as an asymmetric bistratified amacrine cell suggested to play a role in the formation of complex ganglion cell receptive fields. 3. The second was classified as a bistratified amacrine cell. Their processes were stratified at sublayers 1 and 4 of the inner plexiform layer and their morphological features were similar to those of dopaminergic cells in the chick retina.