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Concrete structures can prematurely deteriorate due to the corrosion of reinforcing steel. Corrosion can occur through chloride ingress due to exposure to aggressive media such as seawater and deicing salts. Corrosion causes over $100 billion in damage annually. There are many corrosion mitigation techniques on the market today; these techniques have limited effectiveness as demonstrated by the fact that billions of dollars are still being expended each year due to corrosion-related damage. Therefore, there is a need for innovative approaches to corrosion prevention. This research program used cinnamaldehyde (CA), a bioactive agent derived from cinnamon bark, as a method for corrosion mitigation. Although CA can prevent the corrosion of metals, its hydrophobicity has a negative effect on hydration when incorporated in cementitious systems. In order to avoid these negative consequences while harnessing the anti-corrosive properties, CA was incorporated in a cementitious mixture through the use of lightweight aggregate (LWA). Several tests were carried out to investigate the potential chemical and mechanical effects due to the addition of LWA pre-wet with CA. Promising results were observed, in which the time to corrosion was prolonged by 91 %.

Cumulative evidence suggests that redox dysregulation in cancer cells represents a chemical vulnerability that can be targeted by pharmacological modulation of cellular oxidative stress. According to this emerging mechanism, pharmacological prooxidants may induce deviations from redox homeostasis causing cytotoxicity confined to malignant cells already at a high set point of constitutive oxidative stress leading to functional impairment, cell cycle arrest, and cell death. In contrast, the same prooxidant deviation from redox homeostasis is tolerated by nonmalignant cells that operate at a lower redox set point. This work focuses on experimental redox drug discovery targeting metastatic melanoma cells by pursuing the following specific aims: I. To identify drug-like lead compounds containing redox-directed pharmacophores for prooxidant intervention targeting melanoma in relevant models of the human disease. II. To investigate the molecular mechanism of action underlying antimelanoma activity of our lead compounds comprising Michael acceptors [cinnamaldehyde (CA) and 2,6-dichlorophenolindophenol (DCPIP)] and endoperoxides [dihydroartemesinin (DHA)]. III. To explore the therapeutic potential of drug-like electrophiles for non-melanoma indications including skin photoprotection and genotype-directed cancer chemotherapy. First, we have explored the possibility that prooxidant dietary constituents containing an electrophilic Michael acceptor pharmacophore may display chemotherapeutic activity. Focusing on the cinnamon-derived Michael acceptor CA we have demonstrated significant anti-melanoma activity of this dietary prooxidant observed in vitro and in vivo. Second, we have demonstrated that the synthetic quinoneimine and redox dye DCPIP targets human melanoma cells in vitro and in vivo. DCPIP-apoptogenicity observed in the human melanoma cell lines A375 and G361 was inversely correlated with NAD(P)H:quinone oxidoreductase (NQO1) expression levels. Efficacy against tumors with low NQO1 enzymatic activity including those displaying the human homozygous NQO1*2 missense genotype suggests feasibility of DCPIP-based genotype-directed redox intervention. Third, we demonstrated that the endoperoxide-based antimalarial DHA may serve as an experimental redox chemotherapeutic that selectively induces iron-dependent melanoma cell apoptosis without compromising viability of primary human melanocytes. Given the causative role of redox dysregulation in melanoma and the shortage of efficacious agents currently available, it seems that the emerging therapeutic potential of redox-directed chemotherapeutics for melanoma intervention deserves further evaluation.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-07-28T11:50:50Z No. of bitstreams: 1 francislenejulianamartins.pdf: 1737993 bytes, checksum: 27ec207170bc8ac0b2a6304d77c95420 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-28T12:15:56Z (GMT) No. of bitstreams: 1 francislenejulianamartins.pdf: 1737993 bytes, checksum: 27ec207170bc8ac0b2a6304d77c95420 (MD5) / Made available in DSpace on 2016-07-28T12:15:56Z (GMT). No. of bitstreams: 1 francislenejulianamartins.pdf: 1737993 bytes, checksum: 27ec207170bc8ac0b2a6304d77c95420 (MD5) Previous issue date: 2016-04-26 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O tratamento farmacológico da onicomicose é, geralmente, prolongado, pouco efetivo, de custo elevado e pode acarretar reações adversas. Em 25 % dos casos, essa terapia não apresenta resposta satisfatória. Todos esses fatores levam à busca por novos compostos para uso terapêutico. Dessa forma, este trabalho teve por objetivo avaliar a atividade antifúngica de cinamaldeído, eugenol e α-metil-transcinamaldeído e desenvolver uma formulação para o tratamento contra os principais fungos causadores da onicomicose. Para tanto, foi avaliada a atividade antifúngica dos compostos, na concentração de 1000 µg/mL frente a Trichophyton mentagrophytes ATCC 11481; Fusarium oxysporum ATCC 48112, Fusarium solani ATCC 36031, Microsporum canis ATCC 32903, Microsporum gypseum ATCC 14683, Trichophyton rubrum URM 1666 e Epidermophyton floccosum CCF-IOC-3757. Além disso, foi estabelecida a concentração inibitória mínima (CIM), entre 0,12 a 1000 µg/mL para fungos filamentosos citados e T. mentagrophytes isolado clínico e 2,44 a 5000 µg/mL para Candida albicans ATCC 10231 e C. albicans isolado clínico e a concentração fungicida mínima (CFM) frente as mesmas espécies. O cetoconazol, a terbinafina, o itraconazol e a anfotericina B foram utilizados como fármacos de referência. Para estes fármacos e o composto mais promissor, foram verificadas as alterações morfológicas provocadas sobre as linhagens testadas por meio de microscopia eletrônica de varredura. Além disso, foi avaliada a interferência com a atividade de fosfolipase em C. albicans e foi realizado o ensaio de toxicidade aguda com a utilização do bioindicador Daphnia magna. Do mesmo modo, foi avaliado o percentual de viabilidade celular sobre fibroblastos L 929, realizada a citometria de fluxo para avaliar as alterações sobre F. oxysporum e foi elaborada uma formulação com cinamaldeído a 2 %. Os resultados mostraram que o cinamaldeído foi eficaz contra todos os micro-organismos testados, sendo mais ativo que os demais compostos avaliados. Foi ativo contra F. oxysporum, F. solani e E. floccosum, que não foram inibidos pelos fármacos de referência e mais ativo frente a T. rubrum. As eletromicrografias mostraram que o cinamaldeído provocou alterações nas estruturas dos fungos filamentosos e da levedura, as quais podem ser indicativas de seu mecanismo de ação e provocou redução na atividade de fosfolipase em C. albicans. Nos ensaios de toxicidade aguda, o cinamaldeído foi considerado moderadamente tóxico à D. magna e, abaixo de 1 µg/mL, não interferiu com a viabilidade celular em fibroblastos L 929. A citometria de fluxo mostrou que o cinamaldeído causou a redução na concentração de lipídios neutros, viabilidade celular e interferiu com a atividade mitocondrial de F. oxysporum. A formulação elaborada foi testada in vitro e inibiu T. mentagrophytes, F. oxysporum, M. gypseum e C. albicans. Os resultados obtidos são promissores, mas faz-se necessário verificar a permeabilidade do ativo na formulação e realizar os ensaios in vivo. / Pharmacological treatment of onychomycosis is usually extended, halfhearted, high cost and can brings adverse reactions. In 25 % of cases, this therapy has no satisfactory answer. All of these factors lead to the search for new compounds for therapeutic use. Thus, this study aimed to evaluate the antifungal activity of cinnamaldehyde, eugenol, and α-methyl-trans-cinnamaldehyde and develop a formulation for the treatment against the main causative fungi of onychomicosis. It was evaluated the antifungal activity of compounds, at concentration of 1000 µg/mL against Trichophyton mentagrophytes ATTC 11481; Fusarium oxysporum ATCC 48112, Fusarium solani ATCC 36031, Microsporum canis ATCC 32903, Microsporum gypseum ATCC14683, Trichophyton rubrum URM 1666 and Epidermophyton floccosum CCF-IOC-3757. In addition, it was established the minimum inhibitory concentration (MIC), between the 0.12 to 1000 µg/mL for filamentous fungi cited and Trichophyton mentagrophytes clinical strain and 2.44 to 5000 µg/mL for C. albicans ATCC 10231 and C. albicans clinical strain and minimum fungicide concentration (MFC) against the same strains. Ketoconazole, terbinafine, itraconazole and amphotericin B were used as reference drugs. For these drugs and the most promising compound, were observed morphological changes caused on the tested strains by means of scanning electron microscopy. Furthermore, interference with phospholipase activity in C. albicans was evaluated and the acute toxicity test was developed with the use of bio-indicator Daphnia magna. As well, cell viability percentage was measured on L 929 fibroblast, flow cytometry was performed to assess the changes of F. oxysporum and a formulation with 2 % cinnamaldehyde was developed. The results show that cinnamaldehyde was effective against all tested microorganisms, being more active than the other compounds evaluated. It was active against F. oxysporum, F. solani and E. floccosum, which were not inhibited by the reference drugs and more active against T. rubrum. The micrographs showed that cinnamaldehyde caused changes in the structure of filamentous fungi and yeast, which may be indicative of their mechanism of action and caused reduction of phospholipase activity in C. albicans. In acute toxicity tests, the cinnamaldehyde was considered moderately toxic to D. magna and below 1 µg/mL did not interfere with cell viability in L 929 fibroblasts. Flow cytometry showed that cinnamaldehyde caused reduction in the concentration of neutral lipids, cell viability and interfered with mitochondrial activity of F. oxysporum. The formulation prepared was tested in vitro and inhibited T. mentagrophytes, F. oxysporum, M. gypseum and C. albicans. The results are promising, but it is necessary to check the permeability of the active in the formulation and conduct in vivo testing.

Foram desenvolvidos três experimentos para avaliação de uma mistura de extratos vegetais de orégano, pimenta e canela na produção de frangos de corte: Experimento I - Utilizou-se 320 pintos machos de um dia de idade da linhagem Cobb 500, distribuídos em delineamento experimental inteiramente casualisado com quatro tratamentos (0, 75, 150 e 225 ppm de extratos vegetais) com dez repetições de oito aves cada, criadas até 21 dias para determinação da digestibilidade dos nutrientes das dietas, pela metodologia de coleta do conteúdo ileal. Experimento II - Utilizou-se 600 pintos machos de um dia de idade da linhagem Cobb 500, distribuídos em delineamento experimental inteiramente casualisado com cinco tratamentos (Controle Positivo (CP) com 54 ppm de Bacitracina de Zinco; Controle Negativo (CN) sem aditivos melhoradores de desempenho; CN com a adição de 75 ppm; 150 ppm e 225 ppm de extratos vegetais) com dez repetições de doze aves cada para avaliação de desempenho e características de carcaça. Experimento III - Utilizou-se 600 pintos machos de um dia de idade da linhagem Cobb 500, distribuídos em delineamento experimental inteiramente casualisado com cinco tratamentos (Controle Positivo (CP) com 54 ppm de Bacitracina de Zinco; Controle Negativo (CN) sem aditivos melhoradores de desempenho; CP até 33 dias e posteriormente substituído pelo CN, no período de 34 a 42 dias de idade, com a adição de 75 ppm; 150 ppm e 225 ppm de extratos vegetais) com dez repetições de doze aves cada para avaliação de desempenho e características. Todos os dados foram analisados pelo Statistical Analysis System (SAS Institute Inc., 2008), submetidos à análise de regressão polinomial pelo procedimento GLM ao nível de 5% de significância. No experimento I, não foi observado efeito significativo entre os tratamentos para digestibilidade ileal da energia bruta, e a digestibilidade ileal da proteína bruta e dos aminoácidos apresentou efeito quadrático (P<0,05). No experimento II o consumo de ração não apresentou efeito significativo entre os tratamentos, já para ganho de peso e conversão alimentar foi observado efeito significativo (P<0,05) na comparação entre o antibiótico e os níveis de extratos vegetais adicionados a dieta. No experimento III, não foi observado efeito significativo entre os tratamentos para consumo de ração e ganho de peso, mas a conversão alimentar apresentou efeito significativo (P<0,05) na comparação entre o antibiótico e os níveis de extratos vegetais adicionados a dieta. Nos experimentos II e III, para as características de carcaça não foram observados efeitos significativos (P<0,05) entre os tratamentos. Concluiu-se que a inclusão de uma mistura de extratos vegetais de orégano, pimenta e canela na dieta de frangos de corte em substituição aos aditivos melhoradores de desempenho proporcionou maior digestibilidade ileal da proteína bruta e dos aminoácidos, e de acordo com os níveis praticados, os extratos vegetais não proporcionaram efeitos positivos no desempenho quando comparados com o tratamento com antibiótico, no período total de criação. Entretanto, o fornecimento na fase final apresentou um comportamento diferente, melhorando o rendimento de peito. / We developed three experiments to evaluate a mixture of herbal extracts of oregano, pepper and cinnamon in the production of broilers: Experiment I - was used 320 male chicks from one day old Cobb 500, distributed in completely randomized design with four treatments (0, 75, 150 and 225 ppm of plant extracts) with ten replicates of eight birds each, created up to 21 days to determine the nutrient digestibility of diets, the collection methodology of the ileal content. Experiment II - was used 600 male chicks from one day old Cobb 500, distributed in completely randomized design with five treatments (Positive Control (PC) with 54 ppm Bacitracin Zinc; Negative Control (NC) without enhancing additives performance; CN with the addition of 75 ppm, 150 ppm and 225 ppm of plant extracts) with ten replicates of twelve chicks each to assess performance and carcass characteristics. Experiment III - was used 600 male chicks from one day old Cobb 500, distributed in completely randomized design with five treatments (Positive Control (PC) with 54 ppm Bacitracin Zinc; Negative Control (NC) without enhancing additives performance; CP up to 33 days and subsequently replaced by CN, from 34 to 42 days of age, with the addition of 75 ppm, 150 ppm and 225 ppm plant extracts), with ten replicates of twelve chickens each for performance evaluation and characteristics. All data were analyzed using Statistical Analysis System (SAS Institute Inc., 2008), submitted to polynomial regression analysis by GLM procedure at the 5% level of significance. In the first experiment, no significant effect was observed between treatments for ileal digestibility of raw energy and ileal digestibility of crude protein and amino acids showed a quadratic effect (P <0.05). In experiment II feed intake had no significant effect between treatments, as for weight gain and feed conversion was no significant effect (P <0.05) in the comparison between the antibiotic and the levels of plant extracts added to the diet. In experiment III, no significant effect was observed between treatments for feed intake and weight gain, feed conversion but significant effect (P <0.05) in the comparison between the antibiotic and the levels of plant extracts added to the diet. In experiments II and III, for carcass traits were not significant effects (P <0.05) among treatments. It was concluded that the inclusion of a mixture of herbal extracts of oregano, pepper and cinnamon in the diet of broilers in place of performance enhancing additives provided higher ileal digestibility of crude protein and amino acids, and according to the levels prevailing, vegetable extracts yielded no positive effect on performance when compared with the antibiotic treatment, the total periods. However, the provision in the final phase showed a different behavior by improving the yield of breast.

Foram desenvolvidos três experimentos para avaliação de uma mistura de extratos vegetais de orégano, pimenta e canela na produção de frangos de corte: Experimento I - Utilizou-se 320 pintos machos de um dia de idade da linhagem Cobb 500, distribuídos em delineamento experimental inteiramente casualisado com quatro tratamentos (0, 75, 150 e 225 ppm de extratos vegetais) com dez repetições de oito aves cada, criadas até 21 dias para determinação da digestibilidade dos nutrientes das dietas, pela metodologia de coleta do conteúdo ileal. Experimento II - Utilizou-se 600 pintos machos de um dia de idade da linhagem Cobb 500, distribuídos em delineamento experimental inteiramente casualisado com cinco tratamentos (Controle Positivo (CP) com 54 ppm de Bacitracina de Zinco; Controle Negativo (CN) sem aditivos melhoradores de desempenho; CN com a adição de 75 ppm; 150 ppm e 225 ppm de extratos vegetais) com dez repetições de doze aves cada para avaliação de desempenho e características de carcaça. Experimento III - Utilizou-se 600 pintos machos de um dia de idade da linhagem Cobb 500, distribuídos em delineamento experimental inteiramente casualisado com cinco tratamentos (Controle Positivo (CP) com 54 ppm de Bacitracina de Zinco; Controle Negativo (CN) sem aditivos melhoradores de desempenho; CP até 33 dias e posteriormente substituído pelo CN, no período de 34 a 42 dias de idade, com a adição de 75 ppm; 150 ppm e 225 ppm de extratos vegetais) com dez repetições de doze aves cada para avaliação de desempenho e características. Todos os dados foram analisados pelo Statistical Analysis System (SAS Institute Inc., 2008), submetidos à análise de regressão polinomial pelo procedimento GLM ao nível de 5% de significância. No experimento I, não foi observado efeito significativo entre os tratamentos para digestibilidade ileal da energia bruta, e a digestibilidade ileal da proteína bruta e dos aminoácidos apresentou efeito quadrático (P<0,05). No experimento II o consumo de ração não apresentou efeito significativo entre os tratamentos, já para ganho de peso e conversão alimentar foi observado efeito significativo (P<0,05) na comparação entre o antibiótico e os níveis de extratos vegetais adicionados a dieta. No experimento III, não foi observado efeito significativo entre os tratamentos para consumo de ração e ganho de peso, mas a conversão alimentar apresentou efeito significativo (P<0,05) na comparação entre o antibiótico e os níveis de extratos vegetais adicionados a dieta. Nos experimentos II e III, para as características de carcaça não foram observados efeitos significativos (P<0,05) entre os tratamentos. Concluiu-se que a inclusão de uma mistura de extratos vegetais de orégano, pimenta e canela na dieta de frangos de corte em substituição aos aditivos melhoradores de desempenho proporcionou maior digestibilidade ileal da proteína bruta e dos aminoácidos, e de acordo com os níveis praticados, os extratos vegetais não proporcionaram efeitos positivos no desempenho quando comparados com o tratamento com antibiótico, no período total de criação. Entretanto, o fornecimento na fase final apresentou um comportamento diferente, melhorando o rendimento de peito. / We developed three experiments to evaluate a mixture of herbal extracts of oregano, pepper and cinnamon in the production of broilers: Experiment I - was used 320 male chicks from one day old Cobb 500, distributed in completely randomized design with four treatments (0, 75, 150 and 225 ppm of plant extracts) with ten replicates of eight birds each, created up to 21 days to determine the nutrient digestibility of diets, the collection methodology of the ileal content. Experiment II - was used 600 male chicks from one day old Cobb 500, distributed in completely randomized design with five treatments (Positive Control (PC) with 54 ppm Bacitracin Zinc; Negative Control (NC) without enhancing additives performance; CN with the addition of 75 ppm, 150 ppm and 225 ppm of plant extracts) with ten replicates of twelve chicks each to assess performance and carcass characteristics. Experiment III - was used 600 male chicks from one day old Cobb 500, distributed in completely randomized design with five treatments (Positive Control (PC) with 54 ppm Bacitracin Zinc; Negative Control (NC) without enhancing additives performance; CP up to 33 days and subsequently replaced by CN, from 34 to 42 days of age, with the addition of 75 ppm, 150 ppm and 225 ppm plant extracts), with ten replicates of twelve chickens each for performance evaluation and characteristics. All data were analyzed using Statistical Analysis System (SAS Institute Inc., 2008), submitted to polynomial regression analysis by GLM procedure at the 5% level of significance. In the first experiment, no significant effect was observed between treatments for ileal digestibility of raw energy and ileal digestibility of crude protein and amino acids showed a quadratic effect (P <0.05). In experiment II feed intake had no significant effect between treatments, as for weight gain and feed conversion was no significant effect (P <0.05) in the comparison between the antibiotic and the levels of plant extracts added to the diet. In experiment III, no significant effect was observed between treatments for feed intake and weight gain, feed conversion but significant effect (P <0.05) in the comparison between the antibiotic and the levels of plant extracts added to the diet. In experiments II and III, for carcass traits were not significant effects (P <0.05) among treatments. It was concluded that the inclusion of a mixture of herbal extracts of oregano, pepper and cinnamon in the diet of broilers in place of performance enhancing additives provided higher ileal digestibility of crude protein and amino acids, and according to the levels prevailing, vegetable extracts yielded no positive effect on performance when compared with the antibiotic treatment, the total periods. However, the provision in the final phase showed a different behavior by improving the yield of breast.

Orientador: Cristiane Duque / Coorientador: AiméeMaria Guiotti / Banca: Marcelle Danelon / Banca: Aline Rogéria Freire de Castilho / Resumo: Embora o tratamento endodôntico convencional reduza significativamente a microbiota presente no interior dos canais radiculares, a permanência de microrganismos devido à complexidade anatômica do sistema de canais radiculares e a resistência destes ao tratamento químico-mecânico pode ocasionar infecções persistentes ou secundárias. Muitos estudos têm explorado o uso de fitoquímicos, buscando obter novos compostos que apresentem propriedades farmacológicas. A curcumina, pigmento amarelo isolado dos rizomas da Curcuma longa (Zingiberaceae), e o cinamaldeido, substância volátil responsável pelo odor e sabor das cascas dos caules de plantas do gênero Cinnamomum (Lauraceae) são possíveis substâncias promissoras. O objetivo do estudo foi avaliar o efeito citotóxico e ação antimicrobiana/antibiofilme de compostos híbridos de curcumina e cinamaldeído sobre microrganismos de interesse endodôntico. Foram realizados ensaios para determinação da Concentração Inibitória Mínima (CIM) e Concentração Bactericida Mínima (CBM) do cinamaldeído, da curcumina e dos 23 híbridos sobre Enterococcus faecalis, Streptococcus mutans, Lactobacillus casei, Actinomyces israelii e Fusobacterium nucleatum. Os melhores compostos foram avaliados em ensaios de biofilme simples (cada cepa bacteriana isoladamente) e dual-espécies (E. faecalis + L. casei, E. faecalis + S. mutans, E. faecalis + A. israelii, E. faecalis + F. nucleatum) em placas de poliestireno objetivando-se determinar o efeito sobre o metabolismo ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Although conventional endodontic treatment significantly reduces the microbiota present inside the root canals, the permanence of microorganisms due to the anatomical complexity of the root canal system and their resistance to chemical-mechanical treatment can lead to persistent or secondary infections. Many studies have explored the use of phytochemicals, seeking to obtain new compounds that present pharmacological properties. Curcumin, a yellow pigment isolated from Curcuma longa rhizomes (Zingiberaceae), and cinnamaldehyde, the volatile substance responsible for the odor and taste of plant stems of the genus Cinnamomum (Lauraceae) are possible promising substances. The objective of the study was to evaluate the cytotoxic effect and antimicrobial action / antibiofilm of hybrid compounds of curcumin and cinnamaldehyde on microorganisms of endodontic interest. The minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBM) of cinnamaldehyde, curcumin and 23 hybrids on Enterococcus faecalis, Streptococcus mutans, Lactobacillus casei, Actinomyces israelii and Fusobacterium nucleatum were determined. The best compounds were evaluated on single biofilms (single bacterial strain) and dual-species biofilms (E. faecalis + L. casei, E. faecalis + S. mutans, E. faecalis + A. israelii, E. faecalis + F. nucleatum) in polystyrene plates to determine the effect on bacterial metabolism using the XTT assay and its viability by counting Colony Forming Units (CFUs) after ... (Complete abstract click electronic access below) / Mestre

The objectives of this work are: 1) to determine whether plant essential oil components influence the ability of Escherichia coli and several Pseudomonas species to form biofilms, and inhibit bacterial quorum sensing; 2) to understand the role of autoinducer-2 (AI-2) in biofilm formation by E. coli W3110. The biofilm formation assays determined that cinnamon, cassia and citronella oils differentially affected growth-normalized biofilm formation by E. coli. Cinnamaldehyde (CA) also inhibited the swimming motility of E. coli. Subinhibitory concentrations of CA were effective at inhibiting two types of acyl homoserine lactone (HSL) mediated quorum sensing (QS), and also AI-2 mediated QS. Because CA is widely used in the food and flavor industries, its potential to affect bacterial QS regulated processes should be recognized. The role of AI-2 mediated QS expression in physiology of E. coli W3110 was pleiotropic, including carbon utilization, fimbriae production, and the biofilm development. Overall, the research presented in this dissertation supported the concept that QS, biofilm formation, and cell adhesion may be broadly correlated. The anti-biofilm and anti-QS capability of CA implies that plant essential oil components might be promising for preventing the formation of detrimental biofilms.

Refrigeration has been found to cause cell elongation in mesophilic enteric organisms like commensal Escherichia coli and E. coli O157:H7. As elongated cells may divide into multiple daughter cells, they may result in underestimation of pathogen numbers in foods when plate counts are used. When E. coli cultures were incubated at 6°C for ≤10 days, cells grew by elongation, did not divide, and lost viability (LIVE/DEAD vitality stain) at similar rates. Substantial fractions of cells in cultures elongating at 6°C were inactivated by an abrupt shift to 37°C. Direct microscopic observation of cells transferred to 37ºC after 5 days at 6°C showed that few or no cells of normal size (≤4µm) divided, while elongated cells (>4 µm) formed multiple daughter cells. Thus the threat from mesophilic pathogens with a low infective dose may be underestimated in refrigerated foods. It was also found that E. coli O157:H7 cultures containing elongated cells prepared at 6 or 15 °C have greater potential to attach to food contact surfaces than those grown at higher temperatures. Interestingly, at 6°C cell elongation was inhibited by ≥ 100 mg/l cinnamaldehyde and ≥ 200 mg/l cinnamaldehyde was lethal. In contrast, at 37°C 200 mg/l cinnamaldehyde initially delayed multiplication of E. coli cells by causing cell elongation, but from 2 to 4 h, growth resumed and cells reverted to normal length. To understand this transient behaviour, genome-wide transcriptional analysis of E. coli O157:H7 was performed at 2 and 4 h exposure to cinnamaldehyde in conjunction with reverse phase-high performance liquid chromatography analysis for cinnamaldehyde and other cinnamic compounds. At 2 h exposure, cinnamaldehyde induced expression of many oxidative stress-related genes, reduced expression of genes involved in DNA replication, synthesis of protein, O-antigen and fimbriae. At 4 h many repressive effects of cinnamaldehyde on E. coli O157:H7 gene expression were reversed. Data indicated that by 4 h, E. coli O157:H7 was able to convert cinnamaldehyde into the less toxic cinnamic alcohol using alcohol dehydrogenase or aldehyde reductase enzymes (YqhD and DkgA). The results also showed that the antimicrobial activity of cinnamaldehyde was likely attributable to its carbonyl aldehyde group.

Refrigeration has been found to cause cell elongation in mesophilic enteric organisms like commensal Escherichia coli and E. coli O157:H7. As elongated cells may divide into multiple daughter cells, they may result in underestimation of pathogen numbers in foods when plate counts are used. When E. coli cultures were incubated at 6°C for ≤10 days, cells grew by elongation, did not divide, and lost viability (LIVE/DEAD vitality stain) at similar rates. Substantial fractions of cells in cultures elongating at 6°C were inactivated by an abrupt shift to 37°C. Direct microscopic observation of cells transferred to 37ºC after 5 days at 6°C showed that few or no cells of normal size (≤4µm) divided, while elongated cells (>4 µm) formed multiple daughter cells. Thus the threat from mesophilic pathogens with a low infective dose may be underestimated in refrigerated foods. It was also found that E. coli O157:H7 cultures containing elongated cells prepared at 6 or 15 °C have greater potential to attach to food contact surfaces than those grown at higher temperatures. Interestingly, at 6°C cell elongation was inhibited by ≥ 100 mg/l cinnamaldehyde and ≥ 200 mg/l cinnamaldehyde was lethal. In contrast, at 37°C 200 mg/l cinnamaldehyde initially delayed multiplication of E. coli cells by causing cell elongation, but from 2 to 4 h, growth resumed and cells reverted to normal length. To understand this transient behaviour, genome-wide transcriptional analysis of E. coli O157:H7 was performed at 2 and 4 h exposure to cinnamaldehyde in conjunction with reverse phase-high performance liquid chromatography analysis for cinnamaldehyde and other cinnamic compounds. At 2 h exposure, cinnamaldehyde induced expression of many oxidative stress-related genes, reduced expression of genes involved in DNA replication, synthesis of protein, O-antigen and fimbriae. At 4 h many repressive effects of cinnamaldehyde on E. coli O157:H7 gene expression were reversed. Data indicated that by 4 h, E. coli O157:H7 was able to convert cinnamaldehyde into the less toxic cinnamic alcohol using alcohol dehydrogenase or aldehyde reductase enzymes (YqhD and DkgA). The results also showed that the antimicrobial activity of cinnamaldehyde was likely attributable to its carbonyl aldehyde group.