The incidence of cancer worldwide has increased over the years, and gastrointestinal cancers (G.I.) are amongst the most common forms of cancer. Nevertheless, there is still no curative treatments for this group of tumors. Nucleoside analogues are widely used in cancer treatment. The prevailing compounds are Gemcitabine (used for pancreatic cancer and other carcinomas), 5-Fluorouracil (used in breast, colon, and other cancers), Cytarabine and Clofarabine (used in leukemias). Gemcitabine, the current standard of care for various forms of solid tumors, has a limited efficacy against pancreatic cancer. The objective of this project was the development of effective drugs against pancreatic cancer. We focused on a novel class of nucleoside analogues designed to bypass the most common cellular road blocks and resistance mechanisms. After an extensive screen for cell killing activity, two lead molecules were exclusively studied: LCB2151 and LCB2132. These two molecules showed high efficacy in killing human cancer cells from three different human G.I. cell lines: BxPC3 and Capan-2, two pancreatic cell lines representative of K-Ras positive and negative tumors, as well as the liver cell line HepG2. LCB2151 showed high efficacy in killing Gemcitabine-resistant cancer cells, and a low toxicity in normal cells. Interestingly, results show that these prodrugs can efficiently bypass key resistance mechanisms developed by cancer cells. The results obtained in this project are promising and could pave the way for a more effective treatment of pancreatic cancer.

The ethanol extract of A. phylicoides was investigated for its antioxidant activity using the DPPH scavenging method. The extract showed good antioxidant results with a EC50 value of 10.64 ± 0.0842 µ/ml. The extract was also tested for antibacterial activity against microorganisms (Staphylococcus aureus, Enterococus faecalis, Bacillus cereus, Bacillus subtilis, Bacillus pumilus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumonia) commonly known to pose a threat in the wellbeing of man. All tested microorganisms were significantly inhibited by the extract with the MIC values ranging from 3.13 µg/ml to 6.25 µg/ml. Folin-Ciocalteu’s reagent method was used to determine total phenolic content of dried and freshly prepared crude extract of A. phylicoides. Higher total phenolic content (28.28 ± 0.019 mg GAC/100g) and antioxidant activity (EC50, 10.64 ± 0.084 µg/ml) was observed in the dried extract compared to the fresh extract with a TPC value of 23.04 ± 0.003 mg GAC/100g and EC50 of 13.97 ± 0.066 µg/ml. Bioassay-guided fractionation of ethanolic extract from aerial parts of Athrixia phylicoides using silica and sephadex column chromatography led to the isolation of four known flavanoids, 5-hydroxy-6,7,8,3’,4’,5’-hexamethoxyflavon-3-ol (1), 3-0- demethyldigicitrin (2), 5,6,7,8,3’,4’-hexamethoxyflavone (3) and Quecertin (4). Due to the low yield, no further tests were done on compound 3. A DPPH-scavenging assay was performed to evaluate the antioxidant activity of the isolated compounds. All the tested compounds showed potent antioxidant activity with EC50 values ranging from 1.27 to 3.41 µg/ml. Compound 4 showed a higher antioxidant activity (EC50, 1.27 µg/ml) than vitamin C (EC50, 2.66 µg/ml) used as a control. The MIC values of the isolated compounds against tested microorganisms varied from 20 to more than 40 µg/ml. All the tested compounds showed no activity against S. aureus, B. pumilus, K. pneumonia and P. aeruginosa at the highest concentration tested (40 µg/ml). These compounds together with the extract were further analyzed by XTT assay on Vero cells. The extract showed a low toxicity effect on the cells at lower concentrations exhibiting EC50 value of 107.8 ± 0.129 µg/ml. Compound 4 showed minimal toxicity effect on the cells with a EC50 value of 81.38±0.331 µg/ml, compared to Compound 1 and 2 which exhibited EC50 values of 27.91 ± 0.181 µg/ml and 28.92 ± 0.118 µg/ml respectively. The results obtained from this study provide a clear rationale for the medicinal uses of Athrixia phylicoides. / Dissertation (MSc)--University of Pretoria, 2010. / Plant Science / unrestricted

Biologiska toxicitetstester utförs genom att exponera en testorganism för olika koncentrationer av kemikalier under en bestämd period. Det finns akuta toxicitetstester och kroniska. Resultat från akuta studier presenteras som EC50-värde (Effect Concentration, affecting 50 % of the population). Tester som används som underlag för riskbedömningar ska utföras på kvalitetsmässigt acceptabelt sätt som grundas på International Organization for Standardization (ISO) och Good Labaratory Practice (GLP). Syftet med studien var att studera toxisk inverkan av kaliumdikromat på encellig sötvattenalg, R. subcapitata, genom att räkna cellantal med två olika instrument: flödescytometer och automatisk cellräknare. Vidare att jämföra testernas EC50 medelvärde mot ISO 8692 angivet värde i precisions syfte och att utvärdera de båda räknemetoderna gällande precision och analystid. Kaliumdikromat användes för tillväxtinhibering vid toxicitetstest. EC50-resultaten visade ingen statistiskt signifikant skillnad mellan de båda instrumenten (p=0,47). Den akuta toxicitetsanalysens precision kunde bekräftas som giltig då båda mätmetoders EC50 medelvärden vid jämförelse med ISO 8692 värde befanns inom bestämda 95% konfidensintervallet. Vid jämförelse av studiens två mätningsmetoder, observerades större spridning kring medelvärdet i cellräknarens resultat, där tre EC50 värden hamnade utanför 95% CI. Däremot visade resultatet från flödescytometern mindre spridning och högre noggrannhet jämfört med cellräknarens. Studien visade att flödescytometer skulle kunna användas i framtida toxikologiska tester med encelliga alger, men det krävs flera upprepade försök för att bekräfta fördelar med analysen i flödescytometern. / Biological toxicity tests are performed by exposing a test organism to different concentrations of chemicals over a certain period of time. Results from acute studies are presented as EC50 (Effect Concentration, affecting 50% of the population). Tests used as a basis for risk assessments shall be performed in a quality acceptable way based on the International Organization for Standardization (ISO) and Good Laboratory Practice (GLP). The aim of this study was to study the toxic effect of potassium dichromate on unicellular green algae R. subcapitata, by counting cells with two different apparatus: flow cytometer and automatic cell counter. Additionally, to compare the EC50 mean values against the ISO 8692 value for control of test precision and to compare accuracy and analytical time of two methods. Potassium dichromate was used for growth inhibition in toxicity tests. The EC50 results showed no statistically significant difference between the two instruments (p = 0.47). The accuracy of acute toxicity analysis was confirmed as valid as both EC50 average measurement values compared to ISO 8692 value were found within the 95% confidence interval. When comparing the two methods of the study, greater spread was observed around the mean value in the cell count's results, where three EC50 values were outside 95% CI. The result of the flow cytometer had less spread and higher accuracy compared to the cell count. The study showed that flow cytometers could be used in future toxicological tests with algae, but several repeated tests are required to confirm the benefits of analysis with the flow cytometer.

This thesis focuses on solution antimicrobial effectiveness for copolyoxetanes with quaternary ammonium and PEG-like side chains. Ring opening copolymerization of 3-((4-bromobutoxy)methyl)-3-methyloxetane (BBOx) and 3-((2-(2-methoxyethoxy) ethoxy) methyl)-3-methyloxetane (ME2Ox) yielded random copolymers with 14-100 (m) mole% BBOx designated P[(BBOx-m)(ME2Ox)]. Reaction of P[(BBOx-m)(ME2Ox)] with dodecyl dimethylamine gave the corresponding quaternary P[(C12-m)(ME2Ox)] polycation salts, designated C12-m. Mole ratios and molecular weights were obtained from 1H-NMR and end group analysis. Differential scanning calorimetry (DSC) studies showed Tg’s between 69 and -34 °C. Minimum inhibitory concentrations (MIC) against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa showed MIC decreasing with increasing C12 mole% reaching a minimum between C12-43 and C12-60. C12-43 had the lowest MIC for all strains. At 5× MIC (challenge:108 cfu/ml), C12 43 kills ≥ 99% of the tested strains within 1 hr. C12-m copolyoxetane cytotoxicity toward human red blood cells, HFF (Human Foreskin Fibroblast) and HDF (Human Dermal Fibroblast) was low, indicating good prospects for biocompatibility. Cx-m copolyoxetane antimicrobial efficacy, hemolytic activity and cytotoxicity were further explored by changing quaternary alkyl chain length. Copolyoxetanes are represented as Cx-50, where 50 is the mole percent quaternary repeat units and ‘x’ is quaternary alkyl chain length (2 to 16 carbons). Reaction of P[(BBOx-m)(ME2Ox)] with a series of tertiary amines yielded the desired quaternary ammonium segment. DSC studies showed Tg’s between -40 °C and -60 °C and melting endotherms for C14-50 and C16-50. A systematic dependence of alkyl chain length on MIC was found with C8-50 being the most effective antimicrobial. Kill kinetics for C8-50 (5× MIC, challenge: 108 cfu/ml) effected >99% kill in 1 hour for S. aureus (7 log reduction). C8-50 efficacy on biomass and cell viability of P. aeruginosa biofilms was investigated. Crystal violet (CV) staining assays demonstrate that C8-50 had no effect on adhesion of already established P. aeruginosa biofilms, but reduced biofilm formation by killing cells prior to attachment. For anti-adhesion assays, noticeable reduction in biofilm mass occurred at concentrations greater than 2× MIC. Viability studies show a substantial log reduction of 2.1 at MIC. The low cytotoxicity of Cx-m copolyoxetanes coupled with low MICs and favorable biofilm results indicate good prospects for therapeutic applications.

Scopo di questa tesi è stato di valutare se le attività biologiche possono essere utilizzate come indicatori di adattamento microbico. Le prove condotte sinora in letteratura si sono concentrate unicamente sull’attività di nitrificazione. Pertanto si è voluto valutare se altre attività biologiche possono essere utilizzate come indicatori d’adattamento. Allo scopo si è prima valutata la sensibilità di alcune importanti proprietà biologiche del suolo (nitrification, fluorescein diacetate (FDA)) e attività enzimatiche (urease, nitrate reductase, phosphatase, arylsulfatase, β-galactosidase, phenol-oxidase and dehydrogenase) allo Zn mediante l’impiego di test ecotossicologici Per le attività più sensibili sono state condotte delle prove di adattamento secondo il protocollo di Rusk. Questo esclude le interferenze dovuto all’ aging. Questo protocollo è basato sul reinoculo di un suolo sterile (contaminato con concentrazioni crescenti di Zn) con sottocampioni di suolo che sono stati precedentemente incubati per un periodo di 4 mesi con e senza Zn Il confronto tra i valori di EC50 delle attività biologiche dei suoli reinoculati ci ha permesso di dimostrare un significativo recupero della β-galactosidase, mentre per il nitrate reductase e la nitrificazione potenziale è stato trovato un chiaro e significativo shift delle curve di dose e risposta, anche se con parziale sovrapposizione del range dell’EC50 stimato. / The purpose of this thesis was to assess whether the biological activities can be used as indicators of the microbial adaptation. The tests conducted so far in the literature have focused only nitrification activity. Therefore we wanted to assess whether other biological activities can be used as indicators of adaptation. To do this you first evaluated the sensitivity of some important biological properties of the soil (nitrification, fluorescein diacetate (FDA)) and enzymatic activities (urease, nitrate reductase, phosphatase, arylsulfatase, β-galactosidase, phenol-oxidase and dehydrogenase) Zn through the use of toxicological test. Then the activities most sensitive were tests to evaluate to adapt according to the protocol by Rusk This method to exclude interferences to two chemical aging in soil, This protocol is based on the reinoculation of sterilized soil (contaminated with increasing Zn concentrations) with sub-samples of soil which have been incubated for 4 months with or without Zn. The comparison between the EC50 of the biological properties of reinoculated soils allow us to demonstrate a significant restoration was found for β-galactosidase, while for nitrate reductase and potential nitrification there was a clear and significant shift of dose response curves but with partial overlap of the EC50 ranges estimation.

Submitted by Nadia Maria Poloni null (nadiapoloni@gmail.com) on 2016-04-16T00:04:34Z No. of bitstreams: 1 Dissertação - Nadia Poloni - completa.pdf: 1931593 bytes, checksum: e8e92f6dc3b3aa46033959f97f62b795 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-04-18T12:53:57Z (GMT) No. of bitstreams: 1 polani_nm_me_ilha.pdf: 1931593 bytes, checksum: e8e92f6dc3b3aa46033959f97f62b795 (MD5) / Made available in DSpace on 2016-04-18T12:53:57Z (GMT). No. of bitstreams: 1 polani_nm_me_ilha.pdf: 1931593 bytes, checksum: e8e92f6dc3b3aa46033959f97f62b795 (MD5) Previous issue date: 2016-02-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O fungo ascomiceto, Pyricularia oryzae, tem distribuição mundial como patógeno do arroz, mas recentemente emergiu como patógeno causando a brusone do trigo no Brasil. Os grupos de fungicidas estrobirulinas e triazóis tem sido intensivamente utilizados para manejo de doenças do trigo há cerca de três décadas. Há relato de resistência de P. oryzae do trigo a estrobirulinas no Brasil e a ineficácia dos fungicidas triazóis aponta para um cenário semelhante. Os triazóis, inibidores da desmetilação de esteróis (DMI), inibem a biossíntese de ergosterol e possuem como alvo a enzima 14α-demetilase, codificada pelo gene cyp51. Em nosso estudo, determinamos as distribuições de frequência da sensibilidade de 180 isolados de P. oryzae do trigo amostrados de sete estados do Centro-Sul do Brasil, com base na EC50 a tebuconazol e epoxiconazol. Descrevemos, também, a presença de mutações no gene cyp51A e reconstruímos sua filogenia reticulada para esclarecer a relação evolutiva entre haplotipos. Relatamos que todas as populações de P. oryzae amostradas se mostraram insensíveis aos fungicidas testados, comparando-se com as doses recomendadas para o manejo da doença no campo. Com base na sequência do gene cyp51A de P. oryzae do trigo, foram detectados oito haplotipos distintos. Foram encontradas sete mutações não-sinônimas, que podem estar correlacionadas com a resistência à DMI's. / The fungus ascomycete Pyricularia oryzae has worldwide distribution as rice pathogen, but it has recently emerged as pathogen causing wheat blast in Brazil. The strobirulin and azole fungicides have been intensively used for management of wheat diseases in the last three decades. The report of resistance of P. oryzae from wheat to strobirulins in Brazil and the inefficiency of azole fungicides indicates a similar scenario. The triazoles represented sterols demethylation inhibitor fungicides group (DMI), characterized by inhibiting the biosynthesis of ergosterol and their target is the 14α-demethylase enzyme, encoded by the cyp51 gene. We determined the azole sensitivity frequency distributions of 180 isolates of P. oryzae of wheat sampled in seven states of the south-central Brazil, based on the EC50 of tebuconazole and epoxiconazole. We described the presence of mutations in the cyp51A gene and built their reticulate phylogeny to identify the evolutionary relationship among haplotypes. We reported that all P. oryzae populations sampled were insensitive to the azoles when compared to the recommended doses for the management of the disease in the field. Based on the sequence of cyp51A gene from P. oryzae of wheat, eight distinct haplotypes were detected. We found seven non-synonymous mutations that could be correlated with resistance to DMI's.

Orientador: Paulo Cezar Ceresini / Resumo: O fungo ascomiceto, Pyricularia oryzae, tem distribuição mundial como patógeno doarroz, mas recentemente emergiu como patógeno causando a brusone do trigo noBrasil. Os grupos de fungicidas estrobirulinas e triazóis tem sido intensivamenteutilizados para manejo de doenças do trigo há cerca de três décadas. Há relato deresistência de P. oryzae do trigo a estrobirulinas no Brasil e a ineficácia dos fungicidastriazóis aponta para um cenário semelhante. Os triazóis, inibidores da desmetilaçãode esteróis (DMI), inibem a biossíntese de ergosterol e possuem como alvo a enzima14α-demetilase, codificada pelo gene cyp51. Em nosso estudo, determinamos asdistribuições de frequência da sensibilidade de 180 isolados de P. oryzae do trigoamostrados de sete estados do Centro-Sul do Brasil, com base na EC50 a tebuconazole epoxiconazol. Descrevemos, também, a presença de mutações no gene cyp51A ereconstruímos sua filogenia reticulada para esclarecer a relação evolutiva entrehaplotipos. Relatamos que todas as populações de P. oryzae amostradas semostraram insensíveis aos fungicidas testados, comparando-se com as dosesrecomendadas para o manejo da doença no campo. Com base na sequência do genecyp51A de P. oryzae do trigo, foram detectados oito haplotipos distintos. Foramencontradas sete mutações não-sinônimas, que podem estar correlacionadas com aresistência à DMI's. / Abstract: The fungus ascomycete Pyricularia oryzae has worldwide distribution as rice pathogen, but it has recently emerged as pathogen causing wheat blast in Brazil. The strobirulin and azole fungicides have been intensively used for management of wheat diseases in the last three decades. The report of resistance of P. oryzae from wheat to strobirulins in Brazil and the inefficiency of azole fungicides indicates a similar scenario. The triazoles represented sterols demethylation inhibitor fungicides group (DMI), characterized by inhibiting the biosynthesis of ergosterol and their target is the 14α-demethylase enzyme, encoded by the cyp51 gene. We determined the azole sensitivity frequency distributions of 180 isolates of P. oryzae of wheat sampled in seven states of the south-central Brazil, based on the EC50 of tebuconazole and epoxiconazole. We described the presence of mutations in the cyp51A gene and built their reticulate phylogeny to identify the evolutionary relationship among haplotypes. We reported that all P. oryzae populations sampled were insensitive to the azoles when compared to the recommended doses for the management of the disease in the field. Based on the sequence of cyp51A gene from P. oryzae of wheat, eight distinct haplotypes were detected. We found seven non-synonymous mutations that could be correlated with resistance to DMI's. / Mestre

This diploma thesis deals with a use of algal test in ecotoxicology. A freshwater algae, Desmodesmus subspicatus, was used to asses the ecotoxicity of selected chemical substances. A spectrophotometry method, of VIS spectrum, was used in evaluation of the EC50. A correlation, between a number of algal cells and the wavelength absorbance at 683 nm, has been determined for this purpose. Following chemicals were tested, 2-[2-[(2,6-dichlorophenyl)amino]phenyl]acetic acid, (RS)-2-[4-(2-methylpropyl)phenyl]propanoic acid and N-(4-hydro-xyphenyl)acetamide. An EC50 value was determined for all these substances and also their ecotoxicity has been evaluated.

No description available.

A citricultura brasileira se destaca no mercado global de citros, apresentando altos valores de produção e produtividade. Dentre as diversas doenças que afetam a cultura, a podridão floral dos citros (PFC) vem ganhando destaque com o deslocamento de áreas produtoras para regiões mais favoráveis à ocorrência desta doença. A PFC, causada por espécies dos complexos Colletotrichum acutatum e C. gloeosporioides, é especialmente problemática em anos de temperaturas amenas e alta umidade. Os citricultores realizam pulverizações preventivas para o controle da PFC todos os anos, embora condições climáticas favoráveis à doença ocorram apenas ocasionalmente. Além do impacto econômico, as frequentes pulverizações com fungicidas aumentam a pressão de seleção sobre isolados resistentes, o que pode interferir na eficiência do controle químico. A utilização de sistemas de previsão de epidemias pode evitar que pulverizações desnecessárias de fungicidas sejam realizadas caso não haja condições favoráveis à ocorrência da doença. Para o desenvolvimento destes sistemas, é imprescindível determinar um limiar de ação para a aplicação de fungicidas nos pomares. Dessa forma, o presente trabalho teve por objetivos: (i) estabelecer um limiar de ação para a aplicação de fungicidas com base na germinação de conídios de C. acutatum que permita o controle a doença igualmente ou de forma mais eficiente do que o sistema de pulverização adotado pelos citricultores do sudoeste paulista; (ii) caracterizar a sensibilidade de isolados dos complexos C. gloeosporioides e C. acutatum à trifloxistrobina e ao tebuconazol in vitro e molecularmente, para identificar possíveis mudanças de sensibilidade das espécies a estes fungicidas. Para a definição do limiar de ação, tratamentos baseados em índices de risco foram comparados ao tratamento testemunha e ao calendário fixo de aplicações, usualmente adotado pelos produtores. A aplicação de fungicidas quando limiar de 15% de germinação de conídios era atingido, foi eficiente em controlar a doença e reduzir o número de aplicações de fungicidas. Nos ensaios de sensibilidade a fungicidas dois métodos foram utilizados para a determinação da CE50: o da diluição em gradiente espiral para trifloxistrobina e tebuconazol e o da inibição da germinação de conídios para a trifloxistrobina. Foram utilizados isolados coletados entre 1999 e 2016. A CE50 média da coleção de isolados de acordo com o método da diluição em gradiente espiral variou de 0,158 a 0,297 μg/ml e 0,1 a 0,182 μg/ml para trifloxistrobina e tebuconazol, respectivamente. Para a trifloxistrobina, de acordo com o método da inibição da germinação, a CE50 média foi de 0,002 μg/ml. Não foram verificadas características moleculares nem valores de CE50 atrelados à mudança de sensibilidade dos isolados. / Brazilian citrus industry represents a significant share in the global citrus market. Amongst several diseases that affect the crop, postbloom fruit drop (PFD) has been gaining prominence in Sao Paulo with the displacement of citrus areas to regions in which weather conditions are more favorable to the occurrence of this disease. PFD, caused by species of the complexes Colletotrichum acutatum and C. gloeosporioides, is especially problematic in years of mild temperatures and high humidity. Citrus growers spray the orchards preventively for PFD control every year, although favorable climatic conditions do not occur regularly. In addition to the economic impact, this practice increases the selection pressure of fungicide resistant isolates, and may decrease the efficiency of chemical control in a long term. The use of disease forecasting systems is able to prevent unnecessary fungicide sprays. For the development of such systems, it is essential to determine an action threshold for the application of fungicides in the orchards. The objectives of this work were: (i) to establish an action threshold for fungicide sprays based on the germination of C. acutatum conidia; (ii) to characterize the sensitivity of C. gloeosporioides and C. acutatum isolates to trifloxystrobin and tebuconazole in vitro and molecularly. Regarding the definition of the action threshold, treatments based on risk indices were compared to the control treatments and calendar based sprays, usually adopted by growers. The 15% conidia germination threshold was efficient in controlling the disease and reducing the number of fungicide applications. In the fungicide sensitivity tests, two methods were used to determine the EC50, the spiral gradient dilution for trifloxystrobin and tebuconazole, and the method of conidial germination inhibition for trifloxystrobin. Isolates collected between 1999 and 2016 were used. The mean EC50 of the isolate collection determined by the spiral gradient dilution method ranged from 0.158 to 0.297 μg/ml and from 0.1 to 0.182 μg/ml for trifloxystrobin and tebuconazole, respectively. Mean EC50 of trifloxystrobin estimated by the conidial germination inhibition method was 0.002 μg/ml. No mutations or EC50 values indicated shifts of fungicide sensitivity on the isolates.