Made available in DSpace on 2015-05-14T13:00:02Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 7083796 bytes, checksum: 2aa6f174655d082d78cc059fc1eef2e0 (MD5) Previous issue date: 2014-03-11 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Mucormycoses are infections that have high rates of morbidity and mortality. They show high resistance to antifungal agents, and there is a limited therapeutic arsenal currently available, therefore, there is a great need to give priority to testing therapeutic agents for the treatment of mucormycosis. Along this line, the use of essential oils and phytoconstituents has been emphasized as a new therapeutic approach. The objective of this work was to investigate the antifungal activity of the essential oil (EO) of Thymus vulgaris, and its constituents thymol and p-cymene against Rhizopus oryzae and Rhizopus microsporus, through microbiological screening, determination of minimal inhibitory concentration (MICs) and minimal fungicidal concentration (MFCs), effects on mycelial growth and germination of sporangiospores, fungal morphology and interaction with ergosterol. Also was evaluated the preclinical acute toxicity in mice. In microbiological screening the T. vulgaris essential oil showed antifungal potential against resistant strains of R. oryzae.The MIC of EO and thymol varied 128 512 μg/mL, but the MFC of EO and thymol varied 512 1024 μg/mL and 128 1024 μg/mL, respectively. The results also showed that EO and thymol significantly inhibited mycelial development and germination of sporangiospores of both species of Rhizopus. Investigation of the mechanism of antifungal action showed that EO and thymol interact with ergosterol. These data indicate that EO of T. vulgaris and thymol possess strong antifungal activity, which can be related to their interaction with ergosterol, supporting the possible use of these products in the treatment of mucormycosis. In preclinical acute toxicology the doses of 125, 250, 500 and 1000 mg/kg intraperitoneally (i.p.) showed depressive activity on the central nervous system (CNS). In addition to these parameters was observed that the doses of 125 and 250 mg/kg did not change the body and organs weight of the animals, but it was observed change some of the hematological parameters of the mice. The EO showed DL50 of 250 mg/kg for male and 459.6 mg/kg for female; however the thymol showed DL50 of 222.3 mg/kg for male and 1551 mg/kg for female. These data indicate that EO of T. vulgaris and thymol possess strong antifungal activity, which can be related to their interaction with ergosterol. / As mucormicoses são infecções que possuem elevadas taxas de morbidade e mortalidade, limitado arsenal terapêutico, devido a resistência aos antifúngicos. Portanto, existe uma significativa necessidade de priorizar, testar e aplicar melhorias terapêuticas para o tratamento das mucormicoses. É nesse contexto, que os óleos essenciais e fitoconstituintes vem se destacando como uma nova abordagem terapêutica. O objetivo deste trabalho foi investigar a atividade antifúngica in vitro do óleo essencial (OE) de Thymus vulgaris L. e de seus componentes majoritários (timol e p-cimeno) contra Rhizopus oryzae e Rhizopus microsporus, através da triagem microbiológica, da determinação da concentração inibitória mínima (CIM) e fungicida mínima (CFM), avaliação dos efeitos dos fitoconstituintes no crescimento micelial, na germinação dos esporos fúngicos, na morfologia fúngica e interação com ergosterol. Também foi avaliada a toxicidade pré-clínica aguda em camundongos. Na triagem microbiológica o óleo essencial de T. vulgaris apresentou um dos melhores perfis antifúngicos contra cepas resistentes de R. oryzae. A CIM dos produtos variou entre 128-512 μg/mL, já as CFMs do óleo essencial e timol variaram entre 512-1024 μg/mL e 128-1024 μg/mL, respectivamente. Os resultados também mostraram que tanto o OE como o timol inibiram significativamente o desenvolvimento micelial e a germinação de esporos de ambas as espécies de Rhizopus. Em seguida foi mostrado que os produtos testados alteram a morfologia de R. oryzae e R. microsporus. Na investigação do mecanismo de ação antifúngica foi evidenciado que o OE e o timol interagem com o ergosterol, esterol presente na membrana dos fungos. No ensaio toxicológico pré-clínica agudo, as doses de 125, 250, 500 e 1000 mg/kg via intraperitoneal (i.p.) apresentaram atividade depressora do sistema nervoso central (SNC). Adicionalmente a estes parâmetros foi evidenciado que o OE e o timol nas doses de 125 e 250 mg/kg não promoveram alterações significativas na evolução ponderal e peso dos órgãos dos camundongos. Entretanto, ambas as doses das drogas-teste alteram alguns parâmetros hematológicos dos camundongos. Após 72 h de observação o OE apresentou DL50 estimada em 250 mg/kg para camundongos machos e 459,6 mg/kg para as fêmeas. Já o timol apresentou DL50 estimada em 222,3 mg/kg para os machos e 1551 mg/kg para as fêmeas. Estes dados indicam que o óleo essencial de T. vulgaris e timol, apresentam forte atividade antifúngica, que pode estar relacionada com a interação com ergosterol e consequentemente lise de membrana.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-17T13:33:41Z No. of bitstreams: 1 rebecamollima.pdf: 1811573 bytes, checksum: 85964eefdd3a90513fcac0f172c11491 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-18T13:41:24Z (GMT) No. of bitstreams: 1 rebecamollima.pdf: 1811573 bytes, checksum: 85964eefdd3a90513fcac0f172c11491 (MD5) / Made available in DSpace on 2017-04-18T13:41:24Z (GMT). No. of bitstreams: 1 rebecamollima.pdf: 1811573 bytes, checksum: 85964eefdd3a90513fcac0f172c11491 (MD5) Previous issue date: 2017-01-24 / A esporotricose é uma micose subcutânea de evolução subaguda a crônica capaz de afetar seres humanos e animais. Distribuída mundialmente, possui maior prevalência nas áreas de clima tropical e temperado, sendo a micose subcutânea mais comum na América do Sul. Seus agentes etiológicos são fungos do complexo Sporothrix schenckii, saprófitas e dimórficos, encontrados no ambiente. No Brasil, o aumento exponencial dos casos em humanos e animais vem sendo observado nas últimas décadas. Nos arredores do estado do Rio de Janeiro, já é observada uma epidemia de origem zoonótica. Aliado a isso, o tratamento desta micose vem sendo motivo de preocupação. O alto custo e toxicidade dos medicamentos, o tempo prolongado de tratamento, e o surgimento de linhagens resistentes aos fármacos de escolha justificam a demanda crescente pela descoberta de novos fármacos. Neste contexto, o presente estudo tem como objetivo identificar os componentes dos óleos essenciais de Myrtus communis L. e Thymus vulgaris L., investigar seus potenciais antifúngicos in vitro frente às principais linhagens causadoras de esporotricose no Brasil, e determinar a citotoxicidade preliminar dos óleos essenciais. Os óleos essenciais de mirta e tomilho foram obtidos comercialmente. O perfil cromatográfico obtido por CG para os dois óleos indicou elevados valores de monoterpernos, 87,1% para a mirta e 98,8% para o tomilho, tendo como componentes majoritários o 1-8 cineol e o timol, respectivamente. Para a avaliação da atividade antifúngica foram utilizadas as seguintes linhagens fúngicas: Sporothrix schenckii ATCC 1099-18, Sporothrix schenckii IPEC 15383, Sporothrix brasiliensis ATCC 5110 e Sporothrix brasiliensis IPEC 17943 e duas linhagens clínicas de Sporothrix schenckii, denominadas genericamente como A e B. O óleo essencial de mirta apresentou atividade antifúngica frente a todas as linhagens em concentrações que variaram de 31,25 a 62,5 µg/mL. Foi observada atividade fungicida frente a todas as linhagens em concentrações acima de 62,5 µg/mL. O óleo essencial de tomilho foi capaz de inibir todas as linhagens em concentrações que variaram de 125 a 250 µg/mL. Foi observada atividade fungicida frente a todas as linhagens em concentrações acima de 250 µg/mL. A anfotericina B e o itraconazol foram utilizados como fármacos de referência. Para estes foi observado que somente duas das linhagens estudadas apresentaram susceptibilidade à anfotericina B e ao itraconazol, todas as linhagens estudadas foram consideradas resistentes, com valores de CIM > 16 µg/mL. Estes resultados sugerem indícios de resistência fúngica das linhagens estudadas em relação aos fármacos de referência empregados no tratamento da esporotricose. As microscopias eletrônicas de varredura das linhagens fúngicas revelaram que, tanto nos fungos expostos aos tratamentos experimentais, quanto naqueles expostos aos fármacos de referência, deformidades na estrutura fúngica quando comparadas ao grupo não tratado foram observadas. Em relação aos ensaios de citotoxicidade realizados com queratinócitos humanos (HACAT) pelo método de redução do MTT, os óleos não apresentaram citotoxicidade nas concentrações equivalentes a seus valores de CIM. / Sporotrichosis is a subcutaneous mycosis with subacute to chronic evolution that can affect humans and animals. Distributed worldwide, it is more prevalent in tropical and temperate climates, being the most common subcutaneous mycosis in South America. Its etiological agents are fungi of the Sporothrix schenckii complex, saprophytic and dimorphic, found in the environment. In Brazil, the exponential increase in cases in humans and animals has been observed in recent decades. In the surroundings of the state of Rio de Janeiro, an epidemic of zoonotic origin is already observed. Allied to this, the treatment of this mycosis has been cause of concern. The high cost and toxicity of the drugs, the prolonged treatment time, and the emergence of resistant strains on drugs of choice justify the growing demand for the discovery of new drugs. In this context, the present study aims to identify the components of the essential oils of Myrtus communis L. and Thymus vulgaris L., to investigate their antifungal potentials in vitro against the main sporotrichosis strains in Brazil, and to determine the preliminary cytotoxicity of essential oils. The essential oils of myrtle and thyme were obtained commercially. The chromatographic profile obtained by GC for the two oils showed high values of monoterpere, 87.1% for myrtle and 98.8% for thyme, with 1-8 cineole and thymol, respectively. The following fungal strains were used: Sporothrix schenckii ATCC 1099-18, Sporothrix schenckii IPEC 15383, Sporothrix brasiliensis ATCC 5110 and Sporothrix brasiliensis IPEC 17943 and two clinical strains of Sporothrix schenckii, referred as A and B. Myrtle essential oil showed antifungal activity against all strains at concentrations ranging from 31.25 to 62.5 μg / mL. Fungicidal activity against all strains was observed at concentrations above 62.5 μg / mL. Thyme essential oil was able to inhibit all lineages at concentrations ranging from 125 to 250 μg / ml. Fungicidal activity was observed against all strains at concentrations above 250 μg / mL. Amphotericin B and itraconazole were used as standard drugs. For these, it was observed that only two of the studied strains showed susceptibility to amphotericin B and itraconazole, all strains studied were considered resistant, with MIC values > 16 μg / mL. These results suggest evidence of fungal resistance of the lines studied in relation to the reference drugs used in the treatment of sporotrichosis. Scanning electron microscopy of fungal lines revealed that, both in the fungi exposed to the experimental treatments and in those exposed to the reference drugs, deformities in the fungal structure when compared to the untreated group were observed. In relation to the cytotoxicity assays performed with human keratinocytes (HACAT) by the MTT reduction method, the oils did not present cytotoxicity at concentrations equivalent to their MIC values.

Submitted by JONÂTAS RAFAEL DE OLIVEIRA null (jroliveira16@hotmail.com) on 2016-04-06T20:01:18Z No. of bitstreams: 1 #TESE COMPLETA.pdf: 2320841 bytes, checksum: da9a41fcb44d79b7879a708f1c2de87e (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-04-08T16:37:41Z (GMT) No. of bitstreams: 1 oliveira_jr_dr_sjc.pdf: 2320841 bytes, checksum: da9a41fcb44d79b7879a708f1c2de87e (MD5) / Made available in DSpace on 2016-04-08T16:37:41Z (GMT). No. of bitstreams: 1 oliveira_jr_dr_sjc.pdf: 2320841 bytes, checksum: da9a41fcb44d79b7879a708f1c2de87e (MD5) Previous issue date: 2016-02-12 / Não recebi financiamento / No presente estudo foram avaliadas algumas atividades biológicas dos extratos de R. officinalis L. (alecrim) e T. vulgaris L. (tomilho), verificando: I. Atividade antimicrobiana sobre biofilmes monomicrobianos de Candida albicans, Staphylococcus aureus, Enterococcus faecalis, Streptococcus mutans e Pseudomonas aeruginosa e associações de C. albicans com cada uma destas bactérias, após determinação da concentração inibitória mínima (CIM) e concentração microbicida mínima (CMM) sobre culturas planctônicas destes micro-organismos; II. Viabilidade celular sobre macrófagos de camundongo (RAW 264.7), fibroblastos gengivais humanos (FMM-1), linhagem tumoral de carcinoma mamário (MCF-7) e linhagem tumoral de carcinoma cervical (HeLa); III. Atividade anti-inflamatória sobre RAW 264.7 estimulada por lipopolissacarídeo (LPS) de Escherichia coli; e IV. Atividade genotóxica. Após verificação da capacidade antimicrobiana dos extratos, por método de microdiluição em caldo, as concentrações mais efetivas foram aplicadas nos demais testes. Sobre os biofilmes mono e polimicrobianos, formados por 48 h em poços de placa de microtitulação, a ação dos extratos foi analisada após exposição de 5 min, com quantificação de UFC/mL e analise de sua viabilidade. Da mesma forma, sobre as linhagens celulares (RAW 264.7, FMM-1, MCF-7 e HeLa), cultivadas por 24 h em placas de microtitulação, os extratos foram analisados com os ensaios de MTT, vermelho neutro (VN) e cristal violeta (CV). Foi analisado o efeito anti-inflamatório dos extratos com ensaio imunoenzimático ELISA, pela quantificação de citocinas pró-inflamatórias (TNF-α e IL-1β). A genotoxicidade dos extratos foi verificada pela frequência de micronúcleos (MN) formados em 1000 células. Os resultados foram analisados por T-Test ou ANOVA e Tukey Test (p ≤ 0,05). Em relação ao extrato de R. officinalis L. foi observada redução significativa de todos os biofilmes após exposição de 5 min, bem como, redução de sua viabilidade. Quanto às células, foi observado viabilidade celular acima de 50% a ≤ 50 mg/mL. O nível de IL-1β não se alterou com as concentrações do extrato, entretanto quando RAW 264.7 foi estimulada por LPS, houve inibição da produção desta citocina. Em relação ao nível de TNF-α, houve modulação da síntese desta citocina, sem e com LPS. Foi constatado também ausência de genotoxicidade, uma vez que, a frequência de MN foi semelhante ou menor ao grupo controle. Em relação ao extrato de T. vulgaris L., todos os biofilmes mono e polimicrobianos apresentaram reduções significativas em comparação ao grupo controle. A viabilidade dos biofilmes também foi reduzida. Sobre todas as linhagens celulares foi observada viabilidade celular acima de 50%. Efeito imunomodulador foi observado na síntese de IL-1β e TNF-α. A formação de MN foi semelhante ou inferior ao grupo controle, em todas as linhagens. Com isso, foi concluído que ambos os extratos foram efetivos sobre biofilmes mono e polimicrobianos, proporcionaram viabilidade celular para as culturas acima de 50%, apresentaram efeito imunomodulador e não foram genotóxicos. / This study performed some biological activities of R. officinalis L. (rosemary) and T. vulgaris L. (thyme) extracts, such as: I. Antimicrobial activity on monomicrobial biofilms of Candida albicans, Staphylococcus aureus, Enterococcus faecalis, Streptococcus mutans and Pseudomonas aeruginosa and C. albicans association with each of these bacteria, after determination of the minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) on planktonic cultures of these microorganisms; II. Cell viability on mouse macrophages (RAW 264.7), human gingival fibroblasts (FMM-1), human breast carcinoma cells (MCF-7) and cervical carcinoma cells (HeLa); III. Anti-inflammatory activity on lipopolysaccharide (LPS)-stimulated RAW 264.7; and IV. Genotoxic activity. After checking the antimicrobial capacity of the extracts by broth microdilution method, the most effective concentrations were applied in the other tests. On mono- and polymicrobial biofilms formed by 48 h in microtitre plate wells, the action of the extracts was analyzed after 5 min exposure, with counting of CFU/mL and analysis of their viability. Likewise, in the cell lines (RAW 264.7, FMM-1, MCF-7 and HeLa cells) cultured for 24 h in microtitre plates, the extracts were analyzed by MTT, neutral red (NR) and crystal violet (CV) assays. By ELISA assay, anti-inflammatory effect of the extracts was analyzed with quantification of proinflammatory cytokines (TNF-α and IL-1β). The genotoxicity of the extracts was verified by the micronuclei frequency (MN) formed in 1000 cells. The results were analyzed by T-Test or ANOVA and Tukey test (p ≤ 0.05). Regarding the R. officinalis L. extract was observed significant reduction of all biofilms after 5 min of exposure, as well as reduction their viability. Additionally, cell viability above 50% to ≤ 50 mg/mL was observed on lineages. The IL-1β level did not change with the concentrations of the extract, but when RAW 264.7 was stimulated by LPS, there was inhibition of the production of this cytokine. In relation to the level of TNF-α, was modulation of the synthesis of this cytokine with and without LPS. It was also observed lack of genotoxicity, since the frequency of MN was similar or less than the control group. Regarding to T. vulgaris L. extract, all mono and polymicrobial showed significant reductions compared to the control group. Their viability was also reduced. On all cell lines was observed cell viability above 50%. Immunomodulatory effect was observed in IL-1β and TNF-α synthesis. The MN formation was similar or lower than the control group in all cell lines. Thus, it was concluded that both extracts were effective on mono- and polymicrobial biofilms, promoted cell viability above 50% for cultures, presented immunomodulatory effect and were non-genotoxic.

Orientador: Jane Maria Bertocco Ezequiel / Resumo: A redução de células somáticas é o maior desafio para a melhoria da qualidade do leite, pois está relacionada com a ocorrência de mastite e consequentemente ao uso de antibióticos para seu controle, e prejuízos para a cadeia agroindustrial do leite. A busca por alternativas ao uso de antibióticos vem incentivando pesquisas na área de plantas medicinais. Diante disso, o presente estudo teve como objetivo avaliar o efeito do uso de óleo essencial de tomilho (TEO) sobre a fermentação ruminal de bovinos, resposta imunológica, produção e qualidade do leite ao longo de 2 experimentos. No primeiro experimento, para avaliar o nível de adição de TEO, por meio de parâmetros de fermentação e metabolismo ruminal, foram utilizados 4 bovinos Nelore (700 ± 44 kg PV), castrados, e canulados no rumen, distribuídos em delineamento quadrado latino 4 × 4, sendo 4 tratamentos experimentais e 4 períodos. Os tratamentos consistiram em: CON = controle, sem TEO; T2 = 2 mL / d de TEO; T4 = 4 mL / d de TEO; e T8 = 8 mL / d de TEO. O TEO teve como principal composto o timol, com 423 g/kg de timol na MS (matéria seca). Os animais foram alojados em baias semicobertas individuais (9 m2) com cochos e bebedouros individuais. Cada período experimental durou 21 dias (14 dias de adaptação e 7 dias de coleta de dados). Já no segundo, foram utilizadas 24 vacas da raça Jersey, com peso médio de 400 kg, em segunda lactação, 50 dias de lactação, com idade média de 36 meses e média de produção de leite de 22,05 kg/di... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The somatic cell count is the biggest challenge to improve milk quality, as it is related to the occurrence of mastitis and consequently to the use of antibiotics for its control, and losses to the agro-industrial milk chain. The search for alternatives to the use of antibiotics has been encouraging research in the area of medicinal plants. Therefore, the current study aimed to evaluate the effect of the inclusion of thyme essential oil (TEO) on the ruminal fermentation, immune response, milk production and quality in 2 experiments. In the first, four rumen-cannulated Nellore steers (700 ± 44 kg BW) were randomly distributed in a 4 × 4 Latin square design and received one of the experimental treatments: CON = control, without TEO; T2 = 2 mL/d TEO; T4 = 4 mL/d TEO; and T8 = 8 mL/d TEO. TEO's main compound was thymol, with 423 g/kg of thymol in DM. The animals were housed in individual semi-covered pens (9 m2) with individual feed bunks and waterers. Each experimental period lasted 21 days (14 d of adaptation and 7 d of data collection). In the second, 24 Jersey cows were used, with an average weight of 400 kg, second lactation, 50 d in milk, with approximately 36 months old and average milk production of 22.05 kg/d. The animals were subjected to two treatments: 0 mL/d TEO (CON) and 8 mL/d TEO (TEO; 423 g/kg thymol in DM), in a completely randomized design and housed in individual pens. In the first experiment, DM intake and digestibility were not affected by TEO addition (aver... (Complete abstract click electronic access below) / Doutor

Current agroecosystem management practices have a negative effect on natural enemies and their ability to control insect pests. Conservation biological control through the addition of flowering resources can manage food resources for natural enemies. These floral resources can also provide multiple ecosystem services. Study goals were to determine if perennial Thymus vulgaris L. was attractive to natural enemies and if so, could it be a dual use resource encouraging pest management and providing harvestable product. In 2018 plots in three locations were used to examine the effect of habitat throughout the growing season on the attractiveness of T. vulgaris. Large numbers of Thysanoptera and Hemiptera were collected in all locations, represented by phytophagous Aphididae and Thripidae, and predatory Anthocoridae. Location influenced other families to varying degrees. Seasonal specimen counts were influenced by vegetation density, floral phenology, and predator/prey relationships. In 2019 replicated plots of three treatments were used to examine if harvesting plant material affected the attractiveness of T. vulgaris to natural enemies. Total specimens in 2019 were not significantly different among treatments, indicating removal of blooms did not significantly affect the attractiveness of T. vulgaris. Significant numbers of Thysanoptera and Hemiptera were again collected in all treatments, represented by phytophagous Aphididae and Thripidae. Greater numbers of Diptera and Hymenoptera were also collected. Significant numbers of Thripidae, Aphididae, Mymaridae, and Platygastridae were found in the Family level analyses. Results from both years indicate T. vulgaris was attractive to natural enemy and phytophagous Families. Data from 2018 suggest natural enemy families were attracted to alternative prey and hosts utilizing the foliage rather than flowers but the use of nectar and pollen cannot be ruled out. Data from 2019 suggest the presence of flowers played an important role in the attractiveness of T. vulgaris to micro-hymenopteran parasitoids, Syrphidae, and native Apidae. In conclusion, Thymus vulgaris has the potential to be a dual use floral resource that benefits growers through supporting native enemy populations and pollination services, as well as provide income from the harvest of foliage. It could also be used as a beneficial, harvestable floral resource in urban gardens to encourage pollinator conservation and natural pest control.

Pseudomonas aeruginosa is an opportunistic, nosocomial pathogen for which antibiotic resistance and biofilm development is common. Quorum sensing communication is known to be a major controlling factor in virulence gene expression, biofilm development, antibiotic resistance factors, and specifically MexAB-OprM multi-drug efflux pump expression in P.aeruginosa. MexAB-OprM efflux pumps contribute to antibiotic resistance of tetracycline and other antibiotics in pseudomonads and other organisms. P.aeruginosa infections are problematic in cystic fibrosis and burn patients; it is also the number one causative agent of respiratory infections for intensive care unit patients. Present day antibiotics are losing the battle against these infections. In theory, quorum sensing inhibitors (QSI) reduce pathogencity of the organism; making it less virulent, thus allowing either the host immune system to clear the infection or use of a QSI in combination with an antibiotic to clear more persistent pathogens. For these reasons two alternative modes of treatment were explored in this study: quorum sensing inhibition by folk-medicinal plant extracts and an example of combination drug therapy, the “thyme-tetracycline effect”. Fifty folk-medicinal plant extracts were screened for potential anti-quorum sensing activity using two quorum sensing inhibition (QSI) reporter strains, Pseudomonas aeruginosa QSIS2 and Chromobacterium violaceum 12725. These were used to test specifically for C4-C6 and C12 HSL quorum sensing inhibition. Of the fifty plants tested, thirty plant families were represented. Eleven plant extracts (basil, chaparral, clove, cranberry, oregano, pomegranate, rosemary, sage, sassafras, thyme and witch hazel) showed C4 HSL quorum sensing inhibition as determined by both assays. Interestingly, five of the plants were from the Lamiaceae family. Thymus vulgaris (thyme), also from the Lamiaceae family, was chosen for further assessment. Previous research has shown that thyme extract can synergistically augment tetracycline activity against tetracycline-resistant Pseudomonas aeruginos, creating the “thyme-tetracycline effect.” Disc diffusion assay, thin layer chromatography (TLC), and TLC bioassay techniques were used to show that thymol is the active component in the thyme extract that augments tetracycline activity against resistant Pseudomonas. This study also showed that thymol is a potent C4 HSL quorum sensing inhibitor. The collective data suggests a potential mode of action for the thyme-tetracycline effect: thymol appears to prevent MexAB-OprM efflux pump gene expression. By blocking MexAB-OprM expression, tetracycline antibiotic accumulation can occur within the cell, thus allowing cellular damage.

Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2016-08-01T19:55:39Z No. of bitstreams: 3 Dissertação- Reginaldo Teixeira Nunes - 2014.pdf: 2255035 bytes, checksum: 70c145eb933df8fd6b89f116a91cade4 (MD5) Ata da Defesa de Mestrado. Reginaldo Texeira Nunes.jpg: 2607204 bytes, checksum: fb38ba2b64baafd566c2d99c81304371 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-08-02T12:26:59Z (GMT) No. of bitstreams: 3 Dissertação- Reginaldo Teixeira Nunes - 2014.pdf: 2255035 bytes, checksum: 70c145eb933df8fd6b89f116a91cade4 (MD5) Ata da Defesa de Mestrado. Reginaldo Texeira Nunes.jpg: 2607204 bytes, checksum: fb38ba2b64baafd566c2d99c81304371 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-08-02T12:26:59Z (GMT). No. of bitstreams: 3 Dissertação- Reginaldo Teixeira Nunes - 2014.pdf: 2255035 bytes, checksum: 70c145eb933df8fd6b89f116a91cade4 (MD5) Ata da Defesa de Mestrado. Reginaldo Texeira Nunes.jpg: 2607204 bytes, checksum: fb38ba2b64baafd566c2d99c81304371 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2014-07-04 / The basidiomycete Cryptococcus neoformans is a pathogenic yeast responsible for causing meningoencephalitis in patients with a compromised immune system, leading to high mortality rates worldwide. Presently available antifungal drugs for treating this disease are not always efficient and they may lead to serious side effects and sometimes to fungal resistance. This situation has caused an increasing search for natural products derived from plants with antifungal action. Cymbopogon winterianus Jowitt (Poaceae), popularly known as citronella and Thymus vulgaris L. (Labiatae), known as thyme, are two plants commonly used in folk medicine. This study aimed at evaluating the biological activity of both C. winterianus and T. vulgaris essential oils (EOs) on C. neoformans clinical isolates. We evaluated the in vitro susceptibility of C. neoformans to each EO by the broth microdilution method, the in vitro interaction between EOs and fluconazole by the checkerboard method, their toxicity on human erythrocytes and their effects on the mitochondrial metabolism of fungal cells. Both EOs showed to possess antifungal activity against the tested isolates, with minimum inhibitory concentrations (MICs) ranging from 32 to 256 μg/mL for C. winterianus and from 32 to 128 μg/mL for T. vulgaris. No synergism between the EOs and fluconazole was observed. C. winterianus and T. vulgaris EOs did not cause hemolysis on human erythrocytes at concentrations corresponding to MIC values, indicating, therefore, low toxicity. The MTT assays showed no alterations on mitochondrial metabolism of fungal cells by C. winterianus at concentrations ≤ 128μg/mL, as well as no alterations at any concentrations corresponding to MIC values by T. vulgaris, suggesting that the main mechanism of action of both EOs is not by interfering with mitochondrial activity. Results show that C. winterianus and T. vulgaris EOs may be promising on the production of new antifungal drugs. / O basidiomiceto Cryptococcus neoformans é uma levedura patogênica causadora de meningoencefalite em pacientes imunocomprometidos, levando a altas taxas de mortalidade em todo o mundo. Os antifúngicos atualmente disponíveis para o tratamento dessa enfermidade nem sempre são eficazes, podendo causar efeitos colaterais graves e levar a casos de resistência. Diante dessa situação, a busca por produtos naturais, com ação antifúngica, oriundos de plantas tem crescido consideravelmente. Cymbopogon winterianus Jowitt (Poaceae), conhecida popularmente como citronela e Thymus vulgaris L. (Labiatae), conhecida como tomilho-branco, são duas plantas comumente utilizadas na medicina popular. Este trabalho avaliou a atividade biológica dos óleos essenciais (OEs) de ambas, em isolados clínicos de C. neoformans. Foram avaliados a suscetibilidade in vitro destes isolados ao OE de cada planta pelo método de microdiluição em caldo, a interação in vitro entre os OEs e fluconazol pelo método de checkerboard, sua toxicidade em eritrócitos humanos e seus efeitos no metabolismo mitocondrial de células fúngicas. Ambos os OEs apresentaram atividade antifúngica, com concentrações inibitórias mínimas (CIMs) variando de 32 a 256μg/mL, para C. winterianus, e de 32 a 128μg/mL para T. vulgaris. Não houve sinergismo entre os OEs e fluconazol. Os OEs de C. winterianus e T. vulgaris não causaram hemólise em eritrócitos humanos nas concentrações correspondentes às CIMs, mostrando-se de baixa toxicidade. Nos ensaios com MTT, observou-se que não houve alterações no metabolismo mitocondrial das células fúngicas por C. winterianus em concentrações iguais ou inferiores a 128μg/mL, e em nenhum dos valores correspondentes às CIMs por T. vulgaris, sugerindo que o principal mecanismo de ação antifúngica desses OEs nas CIMs não ocorre por interferência na atividade mitocondrial. Os resultados obtidos demonstram que OEs de C. winterianus e T. vulgaris podem ser promissores para a produção de novos antifúngicos.