Objetivos: O objetivo deste trabalho foi o desenvolvimento de um modelo farmacocinético/farmacodinâmico (PK/PD) para descrever o efeito antifúngico voriconazol (VRC) contra espécies de Candida. Método: Para alcançar este objetivo as seguintes etapas foram realizadas: i) foi adaptado e padronizado modelo de candidíase disseminada em ratos Wistar imunocompetentes e imunocomprometidos com Candida sp.; ii) foram validados métodos analíticos de LC-MS/MS e LC-UV para o doseamento do VRC em amostras de plasma e microdialisado de tecido; iii) foram estabelecidas as condições para microdiálise do VRC e as taxas de recuperação in vitro, por perda e ganho, e em tecido renal in vivo, por retrodiálise, foram determinadas; iv) foi avaliada a PK não-linear do VRC após administração i.v. bolus das doses de 2,5, 5 e 10 mg/kg e a biodisponibilidade oral foi determinada em roedores; v) a penetração renal do VRC após administração oral das doses de 40 e 60 mg/kg foi determinada em ratos Wistar sadios e infectados com C. albicans ou C. krusei; e (vi) o perfil fungistático do VRC contra C. albicans e C. krusei foi determinado utilizando modelo de infecção experimental in vitro onde foram simuladas as concentrações livres renais do VRC esperadas em humanos após administração oral e i.v. de diferentes posologias. Os dados de cinética e dinâmica obtidos foram modelados com equação de Emax modificada, com auxílio do Scientist®. Resultados e Conclusões: i) O modelo de candidíase disseminada foi adaptado com sucesso para ratos Wistar. C. albicans apresentou maior virulência com Log UFC/g de tecido renal de 5,51 ± 0,56 e 7,29 ± 0,26, após 2 e 7 dias de infecção em animais imunocompetentes, respectivamente. Em animais imunocomprometidos a contagem foi de 6,43 ± 0,59 Log UFC/g após 2 dias de infecção, com morte de todo o grupo dentro de 4 dias. As espécies não-albicans (C. krusei e C. glabrata) apresentaram um perfil de infecção semelhante em animais imunocompetentes (Log UFC/g = 2,98 ± 0,27 para C. krusei e 2,48 ± 0,46 para C. glabrata). Entretanto, nos animais imunocomprometidos, C. krusei promoveu morte de todo o grupo em até 7 dias, enquanto C. glabrata causou apenas um aumento no grau de infecção (Log UFC/g = 6,98 ± 0,48). ii) Os métodos analíticos por LC-UV e LCMS/ MS para quantificação do VRC foram validados. As curvas de calibração foram lineares na faixa de 50 a 2500 ng/mL (r > 0,98) para ambos os métodos. Os ensaios de precisão intra e inter-dia foram > 94,9 e 95,8 %, para microdialisado por HPLC-UV e > 87,5 e 92,3 % para LC-MS/MS em plasma, respectivamente. A exatidão foi > 89,1 % para HPLC-UV e > 88,4 % para LC-MS/MS. iii) A avaliação do VRC por microdiálise mostrou que a recuperação é concentração independente (0,1–2,0 μg/mL). O VRC entretanto, devido a sua moderada lipofilia, liga-se às tubulações do sistema de microdiálise, gerando diferenças entre a recuperação determinada pelo método de perda (retrodiálise) e de ganho (diálise) in vitro, as quais puderam ser corrigidas após o cálculo do coeficiente de ligação do fármaco ao sistema. A recuperação in vivo após correção da ligação ao sistema foi de 24,5 ± 2,8 % iv) A análise dos perfis de plasmáticos do VRC obtidos em ratos Wistar após administração oral mostrou comportamento não-linear, compatível com saturação de eliminação. A avaliação compartimental dos perfis i.v. de diferentes doses, utilizando modelo de três compartimentos com eliminação de Michaelis-Menten, permitiu a determinação da constante de Michaelis (KM) de 0,58 μg/mL e da velocidade máxima da eliminação (VM) de 2,63 μg/h, em média. A modelagem simultânea dos dados plasmáticos (40 mg/kg) e i.v. (10 mg/kg) permitiu a determinação da biodisponibilidade oral do VRC em ratos, que foi de 82,8%. v) A fração de penetração renal do VRC, determinada por microdiálise em ratos sadios e infectados, foi de 0,34 ± 0,01, similar a fração livre do fármaco no plasma (0,34), indicando que as concentrações livres renais de VRC são semelhantes às concentrações livres plasmáticas e que as mesmas não se modificam devido a infecções causadas por Candida sp. vi) Os parâmetros da modelagem PK/PD do efeito do VRC contra espécies de Candida em modelo de infecção experimental in vitro obtidos foram: CE50 de 2,96 μg/mL e Kmax = 0,26 h-1 para C. albicans e CE50 de 3,47 μg/mL e Kmax = 0,51 h-1 para C. krusei. Houve diferença estatística apenas no Kmax para as duas espécies (α = 0,05) indicando uma maior suscetibilidade da C. krusei ao VRC. O modelo PK/PD de Emax modificado utilizado foi capaz de descrever adequadamente os perfis de inibição do crescimento de Candida sp em função do tempo, para todos os regimes terapêuticos do VRC avaliados, podendo ser usado para otimização da terapia com esse fármaco. / Objectives: The aim of this work was the development of a pharmacokineticpharmacodynamic model (PK/PD) to describe the fungistatic effect of voriconazole (VRC) against Candida species. Method: To reach this objective, the following steps were done: i) a disseminated candidiasis model to immunocompetent and immunocompromised Wistar rats with Candida sp was adapted and standardized; ii) analytical methods of LC-MS/MS and LC-UV for measurement of VRC in plasma and microdialysate tissue samples were validated; iii) microdialysis conditions of VRC and the recoveries rate in vitro, by loss and gain, in renal tissue in vivo, by retrodialysis, were determined; iv) the non-linear PK of VRC after i.v. bolus administration of 2.5, 5 e 10 mg/kg doses were evaluated and the oral bioavailability in rodents was estimated; v) tissue penetration of VRC after oral administration of 40 and 60 mg/kg was determined in healthy and infected by C. albicans or C. krusei Wistar male rats; vi) the fungistatic profile of VRC against C. albicans and C. krusei was determined using a experimental infection model in vitro, where the free renal concentrations of VRC expected in humans after oral and iv administration of different dosing regimens were simulated. The kinetic and dynamic data obtained were modeled using an Emax modified model, with aid of Scientist®. Results and Conclusions: i) The disseminated candidiasis model was successfully adapted to Wistar rats. C. albicans showing high virulence with Log CFU/g of renal tissue of 5.51 ± 0.56 and 7.29 ± 0.26, after 2 and 7 days of infection in immunocompetent animals, respectively. In immunocompromised animals, the counting was 6.43 ± 0.59 Log CFU/g after 2 days of infection, with whole group death within 4 days. Non-albicans especies (C. krusei e C. glabrata) showed a similar infection profile in immunocompetent and immunocompromised animals (Log CFU/g = 2.98 ± 0.27 to C. krusei e 2.48 ± 0.46 to C. glabrata). However, in immunocompromised animals, C. krusei causes death in the whole group up to 7 days, instead, C. glabrata causes only a low increase in the infection degree (Log CFU/g = 6.98 ± 0.48). ii) The analytical methods of HPLC-UV and LC-MS/MS to VRC quantification were validated. Linearity was between 50 - 2500 range ng/mL (r > 0.98) for both methods. The intra and inter-day precision assays were > 94.9 e 95.8 %, for microdialysate using LC-UV and > 87.5 e 92.3 % using LCxx MS/MS for plasma, respectively. The accuracy was > 89.1 % for HPLC-UV and > 88.4 % for LC-MS/MS. iii) The evaluation of VRC by microdialysis showed that recovery is concentration independent (0.1–2 μg/mL). VRC, however, due to its moderate lipophilic characteristic, binds to the microdialysis system tubing’s, generating differences between recoveries determined by loss (retrodialysis) and gain (dialysis) in vitro methods, which could be corrected after determination of drug’s binding coefficient to the system. The in vivo recovery determined after correction of system binding was 24.5 ± 2.8 %. iv) VRC plasma profiles analysis obtained from Wistar rats after oral administration showed a nonlinear behavior, compatible with saturable elimination. The compartmental evaluation of i.v. profiles in different doses, employing the a compartment model with Michaelis-Menten elimination, allowed to determine the Michaelis-Menten constant (KM) of 0.58 μg/mL and the maximum velocity (VM) of 2.63 μg/h, in average. The simultaneous modeling of oral (40 mg/kg) and iv (10 mg/kg) plasma data allowed the determination of the oral bioavailability of VRC in rats, equal to 82.8%. v) The VRC renal penetration fraction, determined by microdialysis in healthy and infected rats, was 0.34 ± 0.01, similar to the free unbound fraction in plasma (0.34), showing that VRC free renal concentration levels are similar to the unbound plasma concentrations and that did not change due the infection associated to Candida sp. vi) The parameters of PK-PD modeling of VRC effect against Candida species in the in vitro experimental infection model obtained were: EC50 de 2.97 μg/mL and Kmax = 0.203 h−1 to C. albicans and EC50 of 3.47 μg/mL and Kmax = 0.51 h−1 to C. krusei. There is a statistical difference only in Kmax value for the two species (α = 0.05), showing a higher susceptibility of C. krusei to VRC. The PK/PD Emax modified model employed was able to describe adequately the growth inhibition profiles of Candida sp in function of time, for all VRC dosing regimens evaluated, and can be used for therapy optimization with this drug.

Nos últimos anos, várias espécies de fungos, até então conhecidos como saprófitas do ambiente, têm emergido como importantes patógenos na prática clínica, associados muitas vezes com a resistência aos antimicrobianos disponíveis comercialmente. Dessa forma, o conhecimento de aspectos relacionados à patogenicidade desses micro-organismos, como a formação de biofilme, assim como o perfil de susceptibilidade aos antifúngicos e a novas alternativas terapêuticas faz-se necessário. Uma importante tecnologia neste contexto é a utilização de sistemas nanoestruturados a partir de polímeros biodegradáveis para a veiculação de fármacos. Este trabalho visa verificar em isolados fúngicos emergentes a expressão fenotípica de biofilme através do teste em microplaca de poliestireno e o perfil de susceptibilidade frente a antifúngicos na forma livre e incorporados em sistemas nanoestruturados, através da técnica de microdiluição em caldo. Foram selecionados para o estudo 82 isolados fúngicos potencialmente patogênicos, sendo 26 oriundos do ambiente e 56 procedentes de espécimes clínicos. Quanto à capacidade de formação de biofilme verificou-se que 68 (82,9%) isolados produziram biofilme pelo teste da microplaca, sendo 38 classificados como fortes, 17 como moderados e 13 como fracos produtores. Além disso, observou-se que os isolados clínicos apresentaram maior capacidade de formação de biofilme do que os isolados ambientais. Não houve correlação entre a produção de biofilme e a susceptibilidade aos antifúngicos testados nas células planctônicas. De um modo geral, os fungos foram sensíveis à maioria dos antifúngicos testados neste trabalho. Entretanto, o fluconazol apresentou baixa atividade (CIM≥64μg/mL) para 45% dos isolados avaliados. Com o intuito de investigar o efeito de cetoconazol e de fluconazol associados a nanoestruturas sobre os diferentes fungos apresentados no estudo, também foram desenvolvidas nanocápsulas de poli-ɛ-caprolactona contendo estes fármacos. Análises físico-químicas das nanoestruturas revelaram tamanho médio de partícula variando de 206 nm para as nanocápsulas de cetoconazol (CN) e de 211 nm para as nanocápsulas de fluconazol (FN). Ambas as formulações apresentaram características homogêneas e demonstraram estruturas monodispersas. A eficiência de encapsulação do cetoconazol e do fluconazol nas formulações foi de 86,35 e de 80,5%, respectivamente. Os diversos gêneros investigados parecem se comportar de maneira diferente quando expostos às nanoestruturas dos dois fármacos em estudo, sugerindo que as espécies de Candida poderiam apresentar uma maior susceptibilidade in vitro frente a estas nanoestruturas quando comparadas à forma livre dos antifúngicos em questão. Os resultados obtidos demonstram a potencialidade destas formulações para a veiculação de cetoconazol e fluconazol. Como perspectivas, sugere-se a realização de estudos adicionais para evidenciar o efeito in vitro das nanopartículas sobre os diferentes fungos de importância clínica e ambiental. / In recent years, several fungal species known as environmental saprophytes have emerged as important pathogens in clinical practice, often associated with antimicrobial resistance commercially available. Thus, the knowledge of aspects related to these pathogenic micro-organisms, such as biofilm formation, as well as the profile of susceptibility to antifungal agents and new therapeutic options is necessary. An important technology in this context is the use of nanostructured materials from biodegradable polymers for the placement of drugs. This work aims to examine the emerging fungal isolates in the phenotypic expression of biofilm through the test on polystyrene microplate and the susceptibility profile to antifungals front in the free trade and in the nanostructured systems by the broth microdilution method. In this study, 82 potentially pathogenic fungal isolates were selected, being the 26 from environment originating and the 56 from the clinical specimens. Regarding the ability of biofilm formation was found that 68 (82,9%) isolates produced biofilm by the microplate assay. The isolates were classified as 38 strong, 17 moderate and 13 weak biofilm producers. Moreover, it was noted that clinical isolates showed greater capability for the biofilm formation than the environmental isolates. There was no correlation between the biofilm production and the susceptibility to antifungal agents tested in planktonic cells. In general, the fungi were susceptible of the majority of the antifungal agents tested in this study. However, the fluconazole showed low activity (MIC≥64μg/mL) for 45% of the isolates. In order to investigate the effect of the ketoconazole and the fluconazole associated with nanostructures against different fungi contained in the study, polymeric nanocapsules have also been developed containing these drugs. Physicochemical analyzes showed an average size of nanostructures ranging from 206 nm for the nanocapsules of ketoconazole (CN), and 211 nm for the fluconazole (FN). The formulations showed homogeneous characteristics and demonstrated monodisperse structures. The encapsulation efficiency of ketoconazole and fluconazole in the formulations was 86,35 and 80,5%, respectively. The diverse genera investigated appear to behave differently when exposed to the nanostructures of the two drugs have being studied, suggesting that Candida species could exhibit a greater sensitivity to these nanostructures compared to the free form of antifungal concerned. The results demonstrate the potential of the formulations for the delivery of fluconazole and ketoconazole. As perspectives, we suggest further studies to demonstrate the in vitro effect of the nanoparticles against different fungi from the clinical and the environmental importance.

Objetivos: O objetivo deste trabalho foi o desenvolvimento de um modelo farmacocinético/farmacodinâmico (PK/PD) para descrever o efeito antifúngico voriconazol (VRC) contra espécies de Candida. Método: Para alcançar este objetivo as seguintes etapas foram realizadas: i) foi adaptado e padronizado modelo de candidíase disseminada em ratos Wistar imunocompetentes e imunocomprometidos com Candida sp.; ii) foram validados métodos analíticos de LC-MS/MS e LC-UV para o doseamento do VRC em amostras de plasma e microdialisado de tecido; iii) foram estabelecidas as condições para microdiálise do VRC e as taxas de recuperação in vitro, por perda e ganho, e em tecido renal in vivo, por retrodiálise, foram determinadas; iv) foi avaliada a PK não-linear do VRC após administração i.v. bolus das doses de 2,5, 5 e 10 mg/kg e a biodisponibilidade oral foi determinada em roedores; v) a penetração renal do VRC após administração oral das doses de 40 e 60 mg/kg foi determinada em ratos Wistar sadios e infectados com C. albicans ou C. krusei; e (vi) o perfil fungistático do VRC contra C. albicans e C. krusei foi determinado utilizando modelo de infecção experimental in vitro onde foram simuladas as concentrações livres renais do VRC esperadas em humanos após administração oral e i.v. de diferentes posologias. Os dados de cinética e dinâmica obtidos foram modelados com equação de Emax modificada, com auxílio do Scientist®. Resultados e Conclusões: i) O modelo de candidíase disseminada foi adaptado com sucesso para ratos Wistar. C. albicans apresentou maior virulência com Log UFC/g de tecido renal de 5,51 ± 0,56 e 7,29 ± 0,26, após 2 e 7 dias de infecção em animais imunocompetentes, respectivamente. Em animais imunocomprometidos a contagem foi de 6,43 ± 0,59 Log UFC/g após 2 dias de infecção, com morte de todo o grupo dentro de 4 dias. As espécies não-albicans (C. krusei e C. glabrata) apresentaram um perfil de infecção semelhante em animais imunocompetentes (Log UFC/g = 2,98 ± 0,27 para C. krusei e 2,48 ± 0,46 para C. glabrata). Entretanto, nos animais imunocomprometidos, C. krusei promoveu morte de todo o grupo em até 7 dias, enquanto C. glabrata causou apenas um aumento no grau de infecção (Log UFC/g = 6,98 ± 0,48). ii) Os métodos analíticos por LC-UV e LCMS/ MS para quantificação do VRC foram validados. As curvas de calibração foram lineares na faixa de 50 a 2500 ng/mL (r > 0,98) para ambos os métodos. Os ensaios de precisão intra e inter-dia foram > 94,9 e 95,8 %, para microdialisado por HPLC-UV e > 87,5 e 92,3 % para LC-MS/MS em plasma, respectivamente. A exatidão foi > 89,1 % para HPLC-UV e > 88,4 % para LC-MS/MS. iii) A avaliação do VRC por microdiálise mostrou que a recuperação é concentração independente (0,1–2,0 μg/mL). O VRC entretanto, devido a sua moderada lipofilia, liga-se às tubulações do sistema de microdiálise, gerando diferenças entre a recuperação determinada pelo método de perda (retrodiálise) e de ganho (diálise) in vitro, as quais puderam ser corrigidas após o cálculo do coeficiente de ligação do fármaco ao sistema. A recuperação in vivo após correção da ligação ao sistema foi de 24,5 ± 2,8 % iv) A análise dos perfis de plasmáticos do VRC obtidos em ratos Wistar após administração oral mostrou comportamento não-linear, compatível com saturação de eliminação. A avaliação compartimental dos perfis i.v. de diferentes doses, utilizando modelo de três compartimentos com eliminação de Michaelis-Menten, permitiu a determinação da constante de Michaelis (KM) de 0,58 μg/mL e da velocidade máxima da eliminação (VM) de 2,63 μg/h, em média. A modelagem simultânea dos dados plasmáticos (40 mg/kg) e i.v. (10 mg/kg) permitiu a determinação da biodisponibilidade oral do VRC em ratos, que foi de 82,8%. v) A fração de penetração renal do VRC, determinada por microdiálise em ratos sadios e infectados, foi de 0,34 ± 0,01, similar a fração livre do fármaco no plasma (0,34), indicando que as concentrações livres renais de VRC são semelhantes às concentrações livres plasmáticas e que as mesmas não se modificam devido a infecções causadas por Candida sp. vi) Os parâmetros da modelagem PK/PD do efeito do VRC contra espécies de Candida em modelo de infecção experimental in vitro obtidos foram: CE50 de 2,96 μg/mL e Kmax = 0,26 h-1 para C. albicans e CE50 de 3,47 μg/mL e Kmax = 0,51 h-1 para C. krusei. Houve diferença estatística apenas no Kmax para as duas espécies (α = 0,05) indicando uma maior suscetibilidade da C. krusei ao VRC. O modelo PK/PD de Emax modificado utilizado foi capaz de descrever adequadamente os perfis de inibição do crescimento de Candida sp em função do tempo, para todos os regimes terapêuticos do VRC avaliados, podendo ser usado para otimização da terapia com esse fármaco. / Objectives: The aim of this work was the development of a pharmacokineticpharmacodynamic model (PK/PD) to describe the fungistatic effect of voriconazole (VRC) against Candida species. Method: To reach this objective, the following steps were done: i) a disseminated candidiasis model to immunocompetent and immunocompromised Wistar rats with Candida sp was adapted and standardized; ii) analytical methods of LC-MS/MS and LC-UV for measurement of VRC in plasma and microdialysate tissue samples were validated; iii) microdialysis conditions of VRC and the recoveries rate in vitro, by loss and gain, in renal tissue in vivo, by retrodialysis, were determined; iv) the non-linear PK of VRC after i.v. bolus administration of 2.5, 5 e 10 mg/kg doses were evaluated and the oral bioavailability in rodents was estimated; v) tissue penetration of VRC after oral administration of 40 and 60 mg/kg was determined in healthy and infected by C. albicans or C. krusei Wistar male rats; vi) the fungistatic profile of VRC against C. albicans and C. krusei was determined using a experimental infection model in vitro, where the free renal concentrations of VRC expected in humans after oral and iv administration of different dosing regimens were simulated. The kinetic and dynamic data obtained were modeled using an Emax modified model, with aid of Scientist®. Results and Conclusions: i) The disseminated candidiasis model was successfully adapted to Wistar rats. C. albicans showing high virulence with Log CFU/g of renal tissue of 5.51 ± 0.56 and 7.29 ± 0.26, after 2 and 7 days of infection in immunocompetent animals, respectively. In immunocompromised animals, the counting was 6.43 ± 0.59 Log CFU/g after 2 days of infection, with whole group death within 4 days. Non-albicans especies (C. krusei e C. glabrata) showed a similar infection profile in immunocompetent and immunocompromised animals (Log CFU/g = 2.98 ± 0.27 to C. krusei e 2.48 ± 0.46 to C. glabrata). However, in immunocompromised animals, C. krusei causes death in the whole group up to 7 days, instead, C. glabrata causes only a low increase in the infection degree (Log CFU/g = 6.98 ± 0.48). ii) The analytical methods of HPLC-UV and LC-MS/MS to VRC quantification were validated. Linearity was between 50 - 2500 range ng/mL (r > 0.98) for both methods. The intra and inter-day precision assays were > 94.9 e 95.8 %, for microdialysate using LC-UV and > 87.5 e 92.3 % using LCxx MS/MS for plasma, respectively. The accuracy was > 89.1 % for HPLC-UV and > 88.4 % for LC-MS/MS. iii) The evaluation of VRC by microdialysis showed that recovery is concentration independent (0.1–2 μg/mL). VRC, however, due to its moderate lipophilic characteristic, binds to the microdialysis system tubing’s, generating differences between recoveries determined by loss (retrodialysis) and gain (dialysis) in vitro methods, which could be corrected after determination of drug’s binding coefficient to the system. The in vivo recovery determined after correction of system binding was 24.5 ± 2.8 %. iv) VRC plasma profiles analysis obtained from Wistar rats after oral administration showed a nonlinear behavior, compatible with saturable elimination. The compartmental evaluation of i.v. profiles in different doses, employing the a compartment model with Michaelis-Menten elimination, allowed to determine the Michaelis-Menten constant (KM) of 0.58 μg/mL and the maximum velocity (VM) of 2.63 μg/h, in average. The simultaneous modeling of oral (40 mg/kg) and iv (10 mg/kg) plasma data allowed the determination of the oral bioavailability of VRC in rats, equal to 82.8%. v) The VRC renal penetration fraction, determined by microdialysis in healthy and infected rats, was 0.34 ± 0.01, similar to the free unbound fraction in plasma (0.34), showing that VRC free renal concentration levels are similar to the unbound plasma concentrations and that did not change due the infection associated to Candida sp. vi) The parameters of PK-PD modeling of VRC effect against Candida species in the in vitro experimental infection model obtained were: EC50 de 2.97 μg/mL and Kmax = 0.203 h−1 to C. albicans and EC50 of 3.47 μg/mL and Kmax = 0.51 h−1 to C. krusei. There is a statistical difference only in Kmax value for the two species (α = 0.05), showing a higher susceptibility of C. krusei to VRC. The PK/PD Emax modified model employed was able to describe adequately the growth inhibition profiles of Candida sp in function of time, for all VRC dosing regimens evaluated, and can be used for therapy optimization with this drug.

Nos últimos anos, várias espécies de fungos, até então conhecidos como saprófitas do ambiente, têm emergido como importantes patógenos na prática clínica, associados muitas vezes com a resistência aos antimicrobianos disponíveis comercialmente. Dessa forma, o conhecimento de aspectos relacionados à patogenicidade desses micro-organismos, como a formação de biofilme, assim como o perfil de susceptibilidade aos antifúngicos e a novas alternativas terapêuticas faz-se necessário. Uma importante tecnologia neste contexto é a utilização de sistemas nanoestruturados a partir de polímeros biodegradáveis para a veiculação de fármacos. Este trabalho visa verificar em isolados fúngicos emergentes a expressão fenotípica de biofilme através do teste em microplaca de poliestireno e o perfil de susceptibilidade frente a antifúngicos na forma livre e incorporados em sistemas nanoestruturados, através da técnica de microdiluição em caldo. Foram selecionados para o estudo 82 isolados fúngicos potencialmente patogênicos, sendo 26 oriundos do ambiente e 56 procedentes de espécimes clínicos. Quanto à capacidade de formação de biofilme verificou-se que 68 (82,9%) isolados produziram biofilme pelo teste da microplaca, sendo 38 classificados como fortes, 17 como moderados e 13 como fracos produtores. Além disso, observou-se que os isolados clínicos apresentaram maior capacidade de formação de biofilme do que os isolados ambientais. Não houve correlação entre a produção de biofilme e a susceptibilidade aos antifúngicos testados nas células planctônicas. De um modo geral, os fungos foram sensíveis à maioria dos antifúngicos testados neste trabalho. Entretanto, o fluconazol apresentou baixa atividade (CIM≥64μg/mL) para 45% dos isolados avaliados. Com o intuito de investigar o efeito de cetoconazol e de fluconazol associados a nanoestruturas sobre os diferentes fungos apresentados no estudo, também foram desenvolvidas nanocápsulas de poli-ɛ-caprolactona contendo estes fármacos. Análises físico-químicas das nanoestruturas revelaram tamanho médio de partícula variando de 206 nm para as nanocápsulas de cetoconazol (CN) e de 211 nm para as nanocápsulas de fluconazol (FN). Ambas as formulações apresentaram características homogêneas e demonstraram estruturas monodispersas. A eficiência de encapsulação do cetoconazol e do fluconazol nas formulações foi de 86,35 e de 80,5%, respectivamente. Os diversos gêneros investigados parecem se comportar de maneira diferente quando expostos às nanoestruturas dos dois fármacos em estudo, sugerindo que as espécies de Candida poderiam apresentar uma maior susceptibilidade in vitro frente a estas nanoestruturas quando comparadas à forma livre dos antifúngicos em questão. Os resultados obtidos demonstram a potencialidade destas formulações para a veiculação de cetoconazol e fluconazol. Como perspectivas, sugere-se a realização de estudos adicionais para evidenciar o efeito in vitro das nanopartículas sobre os diferentes fungos de importância clínica e ambiental. / In recent years, several fungal species known as environmental saprophytes have emerged as important pathogens in clinical practice, often associated with antimicrobial resistance commercially available. Thus, the knowledge of aspects related to these pathogenic micro-organisms, such as biofilm formation, as well as the profile of susceptibility to antifungal agents and new therapeutic options is necessary. An important technology in this context is the use of nanostructured materials from biodegradable polymers for the placement of drugs. This work aims to examine the emerging fungal isolates in the phenotypic expression of biofilm through the test on polystyrene microplate and the susceptibility profile to antifungals front in the free trade and in the nanostructured systems by the broth microdilution method. In this study, 82 potentially pathogenic fungal isolates were selected, being the 26 from environment originating and the 56 from the clinical specimens. Regarding the ability of biofilm formation was found that 68 (82,9%) isolates produced biofilm by the microplate assay. The isolates were classified as 38 strong, 17 moderate and 13 weak biofilm producers. Moreover, it was noted that clinical isolates showed greater capability for the biofilm formation than the environmental isolates. There was no correlation between the biofilm production and the susceptibility to antifungal agents tested in planktonic cells. In general, the fungi were susceptible of the majority of the antifungal agents tested in this study. However, the fluconazole showed low activity (MIC≥64μg/mL) for 45% of the isolates. In order to investigate the effect of the ketoconazole and the fluconazole associated with nanostructures against different fungi contained in the study, polymeric nanocapsules have also been developed containing these drugs. Physicochemical analyzes showed an average size of nanostructures ranging from 206 nm for the nanocapsules of ketoconazole (CN), and 211 nm for the fluconazole (FN). The formulations showed homogeneous characteristics and demonstrated monodisperse structures. The encapsulation efficiency of ketoconazole and fluconazole in the formulations was 86,35 and 80,5%, respectively. The diverse genera investigated appear to behave differently when exposed to the nanostructures of the two drugs have being studied, suggesting that Candida species could exhibit a greater sensitivity to these nanostructures compared to the free form of antifungal concerned. The results demonstrate the potential of the formulations for the delivery of fluconazole and ketoconazole. As perspectives, we suggest further studies to demonstrate the in vitro effect of the nanoparticles against different fungi from the clinical and the environmental importance.

Orientadores: Maria Luiza Moretti, Rogerio de Jeus Pedro / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-11T04:29:37Z (GMT). No. of bitstreams: 1 Delgado_AnaCeciliaNastrini_D.pdf: 4216034 bytes, checksum: 9c8e2de690455b1af06e61e9e3ce2bd6 (MD5) Previous issue date: 2008 / Resumo: OBJETIVOS: Avaliar a incidência de colonização oral por Candida spp. em pacientes com HIV em uso de terapia anti-retroviral, comparando os resultados dos grupos de pacientes colonizados e não colonizados, assim como estudar os aspectos microbiológicos das cepas isoladas. PACIENTES E MÉTODOS: Foi realizado estudo transversal de pacientes assistidos no HC/Unicamp, de agosto de 2003 a abril de 2004, com coleta única por paciente de swab da cavidade oral. CHROMagar Candida® e ID32C® foram utilizados no cultivo, isolamento e identificação de Candida spp. e Candida Check® na determinação dos sorotipos de C. albicans. C. dubliniensis foi identificada por seqüenciamento no aparelho ABI PRISM 3100® GENETIC ANALYZER. O perfil genômico foi estudado por PFGE, usando o sistema CHEF e a sensibilidade aos azólicos, 5-fluocitosina, anfotericina B e nistatina, baseada na microdiluição em caldo (CLSI). Por meio da revisão dos prontuários foi avaliado: gênero, idade, raça, ano de diagnóstico da infecção pelo HIV, tipo de exposição ao HIV, carga viral, contagem de linfócito TCD4+, infecções oportunistas, classificação clínica da infecção pelo HIV, terapia anti-retroviral e terapia antifúngica. RESULTADOS: Foram identificados 140/324 pacientes colonizados e 184/324 não colonizados: gênero masculino (63% e 60%), exposição sexual (81,5% e 80,5%) e idade média de 38,9 anos. A presença de colonização/infecção foi significativamente maior em pacientes com carga viral detectável (p=0,002) e CD4+<200/mm3 (p=0,006). Foi evidenciada incidência de candidíase oral (31,2%), tuberculose (20,9%), herpes zoster (16,3%), pneumonia por Pneumocystis carinii (PCP) (15,7%) e toxoplasmose (11,7%), no total de pacientes estudados. Não foi observada diferença significativa de colonização por Candida entre os pacientes em uso de TARV com ou sem IP. O uso prévio de nistatina foi maior no grupo colonizado (p=0,014). Foram isoladas 115/154 C. albicans sorotipo A, 15/154 C. albicans sorotipo B e 24/154 Candida não albicans. Doze pacientes apresentaram colonização mista. O estudo genômico de C. albicans sorotipo A identificou 15 perfis diferentes, com predomínio do A1 (56,5%), que mostrou similaridade de 100% entre o perfil de C. albicans sorotipo B predominante B1 (86,6%). O perfil genômico de C. glabrata mostrou-se heterogêneo. C. albicans sorotipo A e B mostraram-se sensíveis a todos os antifúngicos avaliados. C. glabrata e C. krusei apresentaram S-DD para os azólicos. CONCLUSÃO: O trabalho contribuiu de forma significativa para traçar o perfil epidemiológico/clínico dos pacientes HIV em uso de TARV e verificou que o uso de IP não influenciou na presença ou ausência de colonização oral por Candida / Abstract: OBJECTIVES: Evaluating de incidence of oral colonization by Candida spp. in patients in use of antiretroviral therapy, comparing the results of the groups of patients colonized and non-colonized, as well as study the microbiological aspects of the isolated strains. PATIENTS AND METHODS: It was made a cross sectional study assisted at HC/UNICAMP, from August, 2003 to April, 2004, with unique collect of the oral cavity by patient using a swab. CHROMagar Candida® and ID32C® were used in growth, isolation and identification of Candida spp. and Candida Check® for determination of C. albicans sorotypes. C. dubliniensis was identified by sequencing in ABI PRISM 3100® GENETIC ANALYZER device. The genomic profile was studied by PFGE, using the system CHEF and azoles, 5-FC, amphotericin B and nistatine sensibility, based broth microdilution (CLSI). It was evaluated through the review of the prontuaries: genre, age, race, year of HIV infection diagnosis, type of exposition, viral load, TCD4+ linfocyte counting, opportunistic infections, antiretroviral therapy and antifungal therapy. RESULTS: It was identified 140/324 colonized patients and 184/324 non-colonized patients: male gender (63% and 60%), sexual exposition (81,5% and 80,5%) and average age of 39,8 years old. The presence of colonization was significantly greater in patients with detectable viral load (p=0,002) e CD4+<200/mm3 (p=0,006). The incidence of oral candidiasis (31,2%), tuberculosis (20,9%), herpes zoster (16,3%), Pneumocystis carinii pneumonia (PCP) (15,7%) and toxoplasmosis (11,7%) was seen among the total of studied patients. It was not observed a significant difference regarding colonization by Candida among the patients in use of ARVT with or without usage of PI. The early usage of nistatine was bigger in the colonized group (p=0,014). It was isolated 115/154 C. albicans sorotype A, 15/154 C. albicans sorotype B and 24/154 non albicans Candida . Twelve patients presented mixed colonization. The genomic study of C. albicans sorotype A, identified 15 different profiles, with dominance of A1 (56,5%), which shown 100 % similarity between C. albicans sorotype B and predominant B1 (86,6%). The genomic profile of C. glabrata showed heterogeneous. C. albicans serotype A and B showed sensible to all evaluated antifugicals. C. glabrata e C. krusei showed S-DD to azoles. CONCLUSION: This work contributed significantly to trace an epidemiological/clinical profile of the HIV patients in usage of ARV therapy and the lack of influence of IP in the presence or absence of colonization of oral Candida / Doutorado / Ciencias Basicas / Doutor em Clínica Médica

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.

Made available in DSpace on 2014-08-20T14:30:08Z (GMT). No. of bitstreams: 1 Dissertacao_simone_gomes_dias_oliveira.pdf: 1514143 bytes, checksum: c839385a830bc5abebda0ffb2d706d95 (MD5) Previous issue date: 2012-05-21 / Various treatments have been suggested for the treatment of denture stomatitis but problems such as toxicity and antibiotic resistance can be observed. This study evaluated the in vitro antifungal activity, anti-enzymatic and cytotoxic new compounds pirazolínicos. Were used strains of Candida albicans (33), C. parapsilosis (2), C famata (2), C glabrata (2) and C lipolytica (2). The antifungal activity was evaluated by minimum inhibitory concentration (MIC) and Minimum Fungicide (MFC). The anti-enzyme activity was determined in agar medium proteinase and phospholipase. To test for cytotoxicity were used fibroblasts (3T3/NIH) and evaluated by colorimetric assays. The data were submitted to ANOVA and Tukey. The results were: MIC and MFC> 15.6 Sgml for C. albicans; MIC and MFC> 62.5 Sgml for C. parapsilosis, MIC and MFC = 62.5 Sgml for C. famata, MIC and MFC = 125 Sgml for C. glabrata and MIC = 15.6 Sgml for C. lipolytica. The average values of phospholipase and proteinase (Pz) of C. albicans before and after exposure were: 0.6 (± 0.024) and 0.2 (± 0.022) and 0.9 (± 0.074) and 0.3 (± 0.04). These results were not statistically significant for proteinase (p = 0.69) but significant for phospholipase (p = 0.01), and the concentration of 15.6 Sgml the most effective. There were no statistical differences between the groups and the control on the cytotoxicity (p = 0.32). It was found that the derivatives are promising pirazolínicos antifungal agents, either by killing the yeasts or inhibition of the enzyme activity, and its low cytotoxicity / Diversos medicamentos antifungicos vêm sendo sugeridos para o tratamento da estomatite protética porém problemas como toxidade e resistência antimicrobiana podem ser observados. Este estudo objetivou avaliar in vitro o potencial antifúngico, anti-enzimático e citotóxico de novos compostos pirazolínicos. Utilizou-se cepas de Candida albicans(33), C. parapsilosis(2), C. famata(2), C. glabrata(2), C. lipolytica(2). A atividade antifúngica foi avaliada pela Concentração Inibitória Mínima (CIM) e Fungicida Mínima (CFM). A atividade anti-enzimática foi determinada em meios ágar proteinase e fosfolipase. Para o teste de citotoxidade, foram utilizados fibroblastos (3T3/NIH) e avaliado através de ensaio colorimétrico. Os dados foram submetidos aos testes ANOVA e Correlação de Spearman. Os resultados foram: CIM e CFM>15,6Sgml para C. albicans; CIM e CFM>62,5 Sgml para C. parapsilosis; CIM e CFM=62,5 Sgml para C. famata; CIM e CFM=125 Sgml para C. glabrata e CIM=15,6 Sgml para C. lipolytica. Os valores médios de fosfolipase e proteinase (Pz) de C. albicans antes e após a exposição foram respectivamente: 0,2 (±0,022) e 0,6 (±0,024) ; 0,3(±0,04) e 0,9(±0,074) . Estes resultados não foram estatisticamente significantes para proteinase, porém significantes para fosfolipase (p=0,01), sendo a concentração de 15,6 Sgml a mais efetiva. Não foram observadas diferenças estatísticas entre os grupos testados e o controle quanto à citotoxidade. Concluiu-se que os derivados pirazolínicos são promissores agentes antifúngicos, seja através da morte das leveduras ou inibição da sua atividade enzimática, além de apresentarem baixa citotoxidade

Many South Africans continue to use traditional medicine in their daily lives as an alternative form of health care, also as part of their cultural heritage. Medicinal plants are proving to be an important source of novel drugs, and the knowledge provided by traditional healers is a useful tool in the search for antimicrobials. The antimicrobial activity of <M. villosus was investigated against ten bacteria and six fungi. The antibacterial assay showed that the root extract had the highest inhibition against the Gram-positive bacteria at the minimum inhibition concentration of o.1 mg/ml, as well as against the Gram-negative, E. coli, at the MIC of 1.0 mg/ml. Antifungal activity was witnessed against Cladosporium cladosporoide, C. cucumerinum&C sphaerosperum all at the minimum inhibitory concentration of 1.0 mg/ml. An attempt was made to isolate and identify the active antimicrobial compounds. A flavonol, quercetin was isolated and identified by means of UV spectral graphs, and TLC comparison of the plant extract and standard. However, a second isolated antibacterial compound could not be identified fully but it can be said that it is a triterpenoid. / Dissertation (MSc (Botany))--University of Pretoria, 2006. / Plant Science / unrestricted

Thesis (M. Sc. (Botany)) -- University of Limpopo, 2018 / The aim of the study was to investigate medicinal plants used for the treatment of various ailments by the traditional healers and local people and to determine antifungal activities against animal fungal pathogens. Ethnobotanical survey was conducted to identify medicinal plants used by local people and traditional healers to treat various ailments in Makhado Local Municipality, Vhembe District, Limpopo, South Africa. A questionnaire was designed to gather information on the local name of plants, plant parts used and the methods of preparation and administration by the traditional healers. In our findings, sixty-three medicinal plants belonging to thirty-three families were identified to be used for treatment of various diseases such as chest complaint, sexual transmitted infections, headache, swollen legs, hypertension, blood purification, asthma, and infertility. Specific parts of the plant used for medicinal purposes vary from species to species and from one traditional healer to another. The dominant families were Fabaceae, Celastraceae and Euphorbiaceae. Of the sixty-three plants species identified, trees were the most predominant plant form (53%), followed by shrubs (23%), herbs (14%), and climbers (10%). Root, fruit, bark, leaves, seeds and in some instances the whole plant are used for the preparation of medicine while decoction and infusion were the general methods of preparation. The mode of administration of medicine was mainly oral. The most frequently used plant species were Warbugia salutaris (Bertol.f.) Chiov, Sclerocarya birrea (A.Rich) Hochst and Eleondron transvaalense (Burtt Davy) R.H. Archer. Eight plant species (Asparagus buchananii Bak., Albuca seineri (Engl. & K.Krause) J.C Manning & Goldblatt, Elephantorrhiza elephantina (Burch.) Skeels, Indigofera circinnata Benth, Maerua juncea Pax, Pentarrhinum insipidum E. Mey., Senna italica Mill. and Schinus molle L.) were selected based on the information given by the local people and the traditional healers for further phytochemical analysis and microbiological assays. Antifungal activities of the selected plant species were determined against three fungal pathogens namely, Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus. Of the tested plant species, hexane leaf extracts of M. juncea, ethyl acetate leaf extracts of S. italica, A. buchananii and E. elephantina were the most active against Candida albicans, Cryptococcus v neoformans and Aspergillus fumigatus with Minimum inhibitory concentration (MIC) values ranging between 0.02 mg/ml and 0.08 mg/ml. Bioautography assay was used to determine the number of active compounds in the plant extracts. No active compounds were observed in some plant extracts against the tested animal fungal pathogens indicating possible synergism. The most promising plant species were: A. buchananii, A. seineri and M. juncea, all had shown good activity with 4 compounds against A. fumigatus. Acetone and methanol extracts had the same active compounds visible on bioautograms. Most of the active compounds were observed in TLC chromatograms developed Benzene: ethanol: ammonia hydroxide (BEA) eluent solvent system. Based on excellent antifungal activity against the tested microorganisms, leaf extracts of A. buchananii, A. seineri M. juncea, P. insipidum and root extracts of I. circinnata were also tested for cytotoxicity against the Vero kidney cells. All plant extracts investigated were relatively not toxic against the cells with LC50 ranging between 0.131 mg/ml and  1 mg/ml. Water extracts of A. buchananii, A. seineri and M. juncea had LC50  1 mg/ml. The leaf aqueous extracts of P. insipidum were less toxic than root aqueous extracts of I. circinnata with LC50 of 0.65 mg/ml and 0.49 mg/ml against the Vero kidney cells respectively. The results indicate that the local people and traditional healers in Makhado Local Municipality use medicinal plants and their indigenous knowledge on the treatment of fungal infections and related ailments. / University of Limpopo and National Research Foundation (NRF)

Thesis (MScAgric)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: The resistance of plants to infection by phytopathogenic microorganisms is the result of multiple defence reactions comprising both constitutive and inducible barriers. While disease is the exception, such exceptions can be costly and even devastating. In particular, fungal diseases remain one of the major factors limiting crop productivity worldwide, with huge losses that need to be weighed up against massive cash inputs for pesticide treatments. Part of the defence reactions of plants is the synthesis of pathogenesis-related proteins, such as the plant hydrolases, glucanases and chitinases. In recent years, attention has been paid to the implementation of these proteins in plant transformation schemes. The rationale for this approach was that these antimicrobial agents not only degrade the main cell wall components of fungi, but also produce glucosidic fragments that act as elicitors of the biosynthesis of defence metabolites by the host. Furthermore, since these active antimicrobial agents are individually encoded by single genes, these defence systems should and have been shown to be highly amenable to manipulation by gene transfer. In this study, yeast glucanases from Saccharomyces cerevisiae were evaluated for their potential as antifungal proteins. The glucanases tested for their antifungal activity against Botrytis cinerea were the yeast EXG1 and BGL2 genes, encoding an exoglucanase and an endoglucanase respectively. An in vitro assay performed on these glucanases indicated that exoglucanase had a more detrimental effect on B. cinerea hyphal development and growth than the endoglucanase; the former caused typical disruption of the cells and leakage of cell material. The yeast exoglucanase was subsequently subcloned into a plant expression cassette containing the strong constitutive 358 promoter, yielding plasm ids pEXG1 and pMJ-EXG1. The pMJ-EXG1 construct targeted the exoglucanase to the apoplastic region with a signal peptide from an antimicrobial peptide from Mirabilis jalapa, Mj-AMP2. The pEXG1 and pMJ-EXG1 constructs were mobilised into Agrobacterium tumefaciens to facilitate the subsequent tobacco transformation, which yielded transgenic tobacco lines designated E and MJE respectively. Transgene integration was confirmed with southern blot and PCR analyses for both the E and MJE lines. The expression and heterologous production of the EXG1-encoded exoglucanase in the E-transgenic lines was shown with northern blots and activity assays respectively. Moreover, the high level of expression of the yeast exoglucanase led to a decrease in susceptibility of the E lines to B. cinerea infection in comparison to the untransformed tobacco controls. An average decrease in disease susceptibility of 40% was observed in an in planta detached leaf assay. Crude protein extracts from the E lines were also analysed in an in vitro quantitive fungal growth assay, inhibiting in vitro fungal growth by average 20%, thus further confirming the antifungal nature of the yeast exoglucanase. Although integration of the MJ-EXG1 expression cassette was confirmed, no mRNA levels could be detected with northern blot or RT-PCR analysis of the MJE lines. These lines also did not show any in vitro antifungal activities or a decrease in susceptibility to B. cinerea infection in the detached leaf assay. It is suspected that this result is possibly linked to gene silencing, a phenomenon quite frequently associated with heterologous and/or overexpression of glucanases in plant hosts. It appears as if the targeted overexpression to the apoplastic space triggered the gene silencing response, since the intracellularly overexpressed product was produced and shown to display activity. The yeast exoglucanase thus joins the list of silenced glucanases in overexpression studies in plants. Overall, this study confirmed the antifungal characteristics of the Saccharomyces exoglucanase and provides valuable information of the possibility of utilising yeast glucanases in a transgenic environment. A decrease in the susceptibility of tobacco to B. cinerea infection, as shown by the overexpressed EXG1-encoded exoglucanases, merits further investigation into the use of this gene in the engineering of disease-resistant crops. / AFRIKAANSE OPSOMMING: Die weerstand van plante teen infeksie deur fitopatogeniese mikroórganismes is die resultaat van verskeie meervoudige verdedigingsreaksies wat beide konstitutiewe en induseerbare versperrings behels. Terwyl siekte die uitsondering eerder as die reël is, kan sulke uitsonderinge duur en selfs verwoestend wees. In die besonder is swamsiektes een van die vernaamste faktore wat gewasproduksie wêreldwyd beperk, met enorme verliese wat teen kontantinsette vir plaagdoders opgeweeg moet word. Deel van die verdedigingsreaksie van plante is die sintese van patogeen-verwante proteïene, soos die planthidrolases, -glukanases en -chitinases. In die onlangse tyd is aandag geskenk aan die implementering van hierdie proteïene in plant transformasieskemas. Die grondrede hiervoor was dat hierdie antimikrobiese agente nie net die hoof selwandkomponente van swamme kan afbreek nie, maar ook glukosidiese fragmente produseer wat as ontlokkers van metabolietbiosintese vir die verdediging van die gasheer kan optree. Aangesien hierdie aktiewe antimikrobiese agente individueel deur enkele gene enkodeer word, blyk hierdie verdedigingsisteme om hoogs ontvanklik vir manipulasie deur geenoordrag te wees. In hierdie studie is die gisglukanase van Saccharomyces cerevisiae vir hul potensiaal as antifungiese proteïene geëvalueer. Die glukanases wat vir hul antifungiese aktiwiteit teen Botrytis cinerea getoets is, was die gis EXG1- en -BGL2-gene, wat onderskeidelik vir "n eksoglukanase en 'n endoglukanase enkodeer. "n In vitro toets wat op hierdie glukanases uitgevoer is, het aangedui dat die eksoglukanase 'n meer skadelike effek op die hife-groei en -ontwikkeling van B. cinerea as die endoglukanase gehad het; eersgenoemde het die tipiese ontwrigting van die selle en die uitlek van selmateriaal tot gevolg gehad. Die gis-eksoglukanase is gevolglik in 'n plant uitdrukkingskasset wat die sterk konstitutiewe 35S promotor bevat, gesubkloneer, wat plamiede pEXG1 en pMJ-EXG1 opgelewer het. Die pMJ-EXG1-konstruk het die eksoglukanase na die apoplastiese gebied geteiken deur 'n seinpeptied vanaf "n antimikrobiese peptied van Mirabilisjalaba, Mj-AMP2. Die pEXG1- en pMJ-EXG1-konstrukte is in Agrobacterium tumefaciens gemobiliseer, wat die gevolglike tabaktransformasies gefasiliteer het wat die E en MJE transgeniese tabaklyne onderskeikelik gelewer het. Transgeen-integrasie is deur suidelike klad- en PKR-analises vir beide die E en MJE lyne bevestig. Die uitdrukking en heteroloë produksie van die EXG1-enkodeerde eksoglukanase is in die transgeniese E lyne deur noordelike klad en aktiwiteitstoetse onderskeidelik aangetoon. Verder het die hoë uitdrukkingsvlak van die gis-eksoglukanase tot 'n vermindering in die vatbaarheid van die E lyne vir B. cinerea-infeksie relatief tot die ongetransformeerde tabakkontroles gelei. 'n Gemiddelde vermindering in siektevatbaarheid van 40% is in 'n in planta verwyderde-blaartoets waargeneem. Ru proteïen-ekstrakte van die E lyne is ook in 'n in vitro kwantitatiewe swamgroeitoets geanaliseer en het in vitro swamgroei met tot gemiddeld 20% geïnhibeer, wat dus verder die antifungiese aard van die gis-eksoglukanase bevestig het. Alhoewel die integrasie van die pMJ-EXG1 uitdrukkingskasset bevestig is, kon geen mRNA-vlakke met die noordelike klad- of RT-peR-analises van die MJE-Iyne waargeneem word nie. Hierdie lyne het ook geen in vitro antifungiese aktiwiteite of 'n vermindering in die vatbaarheid vir B. cinerea-infeksie getoon nie, soos in die verwyderde-blaartoets uitgevoer is nie. Dit word vermoed dat hierdie resultaat moontlik aan geenstilmaking gekoppel is, 'n verskynsel wat gereeld met heteroloë- en/of ooruitdrukking van glukanases in plantgashere gekoppel word. Dit blyk dat die ooruitdrukking wat tot die apoplastiese ruimte geteiken is, tot die geenstilmaking-respons aanleiding gegee het, aangesien die intrasellulêre ooruitgedrukte produk gemaak is en aktiwiteit getoon het. Die gis-eksoglukanase word dus deel van die lys van stilgemaakte glukanases in die ooruitdrukkingstudies van plante. In die algemeen het hierdie studie dus die antifungiese kenmerke van die Saccharomyces eksoglukanase bevestig en waardevolle inligting oor die moontlike gebruik van gis-glukanases in 'n transgeniese omgewing verskaf. 'n Afname in die vatbaarheid van tabak vir infeksie deur B. cinerea, soos deur die ooruitdrukking van EXG1-enkodeerde eksoglukanase getoon is, verdien dus verdere ondersoek van die gebruik van hierdie geen in die skepping van siekteweerstandbiedende gewasse.