Mice were exposed to diesel exhaust for 9 months prior to evaluation for benzo(a)pyrene disposition. On the last day of exposure the mice were instilled intratracheally with tritiated-benzo(a)pyrene ([3H]BP). The mice were sacrificed at intervals of 2, 24, and 168 hours. Disappearance of radioactivity from lungs and liver was rapid and essentially linear with time. In lungs, liver, and testes; [3H]BP metabolites were found mainly as conjugates, a form readily excretable. Clearance of the hydrocarbon from liver and testes in exposed mice was not markedly different from that in nonexposed mice. However, mice exposed to diesel exhaust had delayed [3H]BP clearance from lungs, possibly due to [3H]BP adsorption to diesel smoke particles.

[pt] Essa dissertação apresenta um estudo comparativo de quatro diferentes modelos de cinética química detalhada que envolvem as principais espécies químicas responsáveis pelo processo de formação e oxidação da fuligem, i.e., o oxigênio molecular, o radical hidroxila, o acetileno, o propargil, benzeno, fenil e pireno. Para este fim, considera-se a combustão de misturas de etileno/ar e metao/ar. Para analisar os modelos cinéticos são utilizados um reator perfeitamente misturado (PSR) e um reator parcialmente misturado (PaSR). No caso do reator perfeitamente misturado, um estudo sistemático da influência do tempo de residência e a riqueza da mistura sobre estas espécies químicas é apresentado. São discutidas as importantes discrepâncias obtidas, para o acetileno, o propargil, o benzeno, o fenil e o pireno, entre os modelos cinéticos analisados. As espécies oxidantes exibem menores discrepâncias dentre todas as espécies analisadas. No caso do reator parcialmente misturado, a razão entre o tempo de residência e o tempo de mistura é o parâmetro de análise. De modo geral, os resultados obtidos permitem avaliar o comportamento dos mecanismos cinéticos em uma situação representativa de combustão em escoamentos turbulentos. / [en] In this dissertation a comparative study is presented of four different detailed kinetics models involving the main chemical species responsible for the soot formation and oxidation, i.e., the molecular oxygen, the hydroxyl, the acetylene, the propargyl, the benzene and the pyrene. To this purpose is considered the combustion of ethylene/air and metane/air. To analyze the kinetic models are used a perfect stirred reactor (PSR) and a partial stirred reactor (PaSR). In the case of a perfect stirred reactor a systematic study of the influence of the residence time and of the equivalence ratio on these chemical species is presented. Are discussed the important discrepancies obtained for acetylene, propargyl, benzene, phenyl and pyrene, between the kinetic models analyzed. The oxidizing species exhibit minor discrepancies only. In the case of the partially mixed reactor, the ratio between the residence time and the mixing time is the analysis parameter. Overall, the results obtained allow to evaluate the behavior of the kinetic mechanisms in situations representative of combustion in turbulent flows.

Ellipticine, an alkaloid isolated from Apocynaceae plants, exhibits significant antitumor and HIV activities. Ellipticine is a pro-drug, whose pharmacological and genotoxic effects depend on activation by cytochromes P450 (CYP) and peroxidases (Px) to a reactive species generating DNA adducts. To elucidate contribution of CYPs (and which of them) and Px to ellipticine activation, we used rat and mouse models, mice with deleted gene of NADPH:CYP reductase in the liver, thus absenting this enzyme in the liver (HRNTM ) and a control mouse line (WT), rats treated with ellipticine, and microsomal systems isolated from the liver of mouse lines and from the liver, kidney and lung of rats. The purified enzymes, CYP1A1 and 3A4, reconstituted with NADPH:CYP reductase were also used. The effect of cytochrome b5, a facultative component of the mixed function monooxygenase system, on ellipticine oxidation by CYP1A1 and 3A4 was also investigated. Carcinogenic benzo(a)pyrene (BaP), known to covalently bind to DNA after its activation with CYPs, was investigated for its potential to generate DNA adducts and to induce CYP and NADPH:CYP reductase enzymes in mouse livers. We investigated an influence of each of components of the mixed function oxidases (MFO) system on metabolism of BaP. CYP1A1 is widely accepted to be the...

Os organismos chamados de algas apresentam uma grande diversidade de espécies e ocupam uma grande variedade de nichos ecológicos. Fundamentais para a manutenção das condições que permitem a vida no planeta, inclusive porque constituem a base de cadeias tróficas de ecossistemas aquáticos, as algas vêm sofrendo com o descarte contínuo de resíduos resultantes das mais variadas atividades humanas. Por outro lado, as algas, ao serem expostas aos poluentes, podem indicar a presença dos mesmos em seus habitats por meio de seus biomarcadores. Neste sentido, este trabalho preocupou-se em caracterizar as bases moleculares da toxicidade do hidrocarboneto policíclico aromático (HPA) benzo(a)pireno (BaP), presente no petróleo cru e derivado da combustão parcial de matéria orgânica, sobre a macroalga vermelha Gracilaria birdiae, uma Rhodophyta marinha nativa. Para avaliar a agressividade do poluente, a alga foi exposta a diferentes concentrações do HPA em água do mar, tanto em situações de exposição aguda (24 e 96h) quanto crônica (7 e 15 dias). Após estes períodos de exposição, alguns biomarcadores bioquímicos e fisiológicos da alga tiveram seus comportamentos analisados. Foram eles: taxas de crescimento (TC); duas defesas antioxidantes: os níveis do tripeptídeo de baixo peso molecular glutationa (GSH) e a atividade da enzima superóxido dismutase (SOD); os níveis do dímero de glutationa GSSG; a fotossíntese da macroalga; e seu aspecto de pigmentação geral. Foi possível observar que BaP é tóxico para a macroalga G. birdiae. Aumentos da concentração do HPA nos meios de cultura das algas provocaram menores TC. A partir destes dados de TC foi possível determinar uma curva de inibição do crescimento da alga e a 7 respectiva IC50 de BaP para um período de exposição de 15 dias, com valor de 69 ng do HPA para cada mL de água do mar. Após diferentes exposições a BaP, incluindo em IC50, algas expostas a BaP apresentaram níveis reduzidos do antioxidante GSH, o mesmo efeito que fora observado para GSSG (com exceção da exposição de 96h). O desempenho fotossintético, a atividade de SOD e a pigmentação de G. birdiae mostraram ser sistemas menos sensíveis à presença de BaP, e foram prejudicados em concentrações mais elevadas do poluente, em torno de 10 a 20 µg/mL. Nestas situações, a despigmentação severa da macroalga foi acompanhada de decaimentos expressivos de alguns parâmetros fotossintéticos (i.e., rETR, RQE, Ik, β) da alga. Numa outra abordagem, alguns experimentos foram feitos com o intuito de descobrir se a alga era capaz de eliminar e biorremediar BaP presente na água do mar. Aparentemente, a alga não apresenta tal capacidade; porém, uma cinética mais detalhada se faz necessária para a confirmação desta observação. Concluindo, os resultados do trabalho corroboram outros dados da literatura a respeito da toxicidade de BaP sobre sistemas vivos. Ainda, apesar de a sensibilidade de G. birdiae a BaP não ter sido alta, foi possível apontar alguns sistemas bioquímicos da alga capazes de desempenhar papel como biomarcadores de exposição ao poluente estudado, o que pode auxiliar na tomada de medidas para o manejo e a conservação de áreas impactadas / Algae show a great biodiversity and occupy many different ecological niches. Besides being essential for the maintenance that allow life on Earth, algae are on the basis of aquatic food chains and they suffer with continuous residue discharge that comes from different human activities. However, once algae are exposed to pollutants, biomarkers can indicate its presence on the environment. The aim of this work was on the characterization of benzo(a)pyrene (BaP; a polycyclic aromatic hydrocarbon (PAH) derived from crude oil and from incomplete combustion of organic matter) toxicity against the red macroalga Gracilaria birdiae, a marine brazillian Rhodophyta. BaP toxicity in marine water was investigated under different exposure concentrations after acute (24 and 96h) and chronic (7 and 15 days) conditions. At the end of the exposures time, some of the algae`s biochemical and physiological biomarkers were analyzed: growth rate (GR); two antioxidant defenses: the low molecular weight peptide glutathione (GSH) and superoxide dismutase (SOD) enzyme activity; glutathione disulfide (GSSG) levels; the macroalga photosynthetic capacity; and the general colour aspect. Increased BaP concentrations led to a decrease of GR values. From GR data it was possible to obtain an inhibition growth curve and the respective BaP IC50 for a 15-day exposure time period with value of 69 ng/mL. After different BaP exposure conditions, including IC50, exposed algae presented decreased GSH levels, the same effects observed for GSSG (except for 96h exposure). The photosynthetic yield, SOD activity and colour aspect of G. birdiae appeared to be more resistant systems against BaP, and were affected only in higher BaP concentrations (10 to 20 µg/mL). In such situations, G. birdiae lost its red colour, which was accompanied by considerable photosynthetic parameters (i.e., rETR, RQE, Ik, β) decay. In a different approach, some experiments were done in order to discover any BaP clean-up and bioremediation played by G. birdiae. Preliminary results suggests that the alga has low remediation efficiency, although more investigations need to be done to confirm this. In summary, the results presented here show similar tendencies with literature data in respect of BaP toxicity against living organisms. Even though G. birdiae presented reasonable resistance to BaP, it was possible to identify some of the alga`s biochemical systems as BaP exposure biomarkers. This situation can be useful for impacted areas assessment and management.

O presente trabalho trata da síntese de sondas fluorescentes visando a detecção e quantificação de íons metálicos e ânions de toxicidade relevante para humanos e meio ambiente. Utilizamos os núcleos fluorescentes da fluoresceína, cumarina e pireno nos processos de síntese, aos quais foram estrategicamente acopladas estruturas capazes de interagir seletivamente com os analitos em questão. Devido às características distintas das sondas, dividimos o trabalho em três capítulos onde cada um abordará uma classe de núcleo fluorescente. No primeiro deles, trataremos de dois derivados de cumarina, onde um deles é capaz de identificar e quantificar o ânion fluoreto, e o outro o íon cobre (II). No segundo capítulo trataremos de dois derivados de fluoresceína homologados à estrutura de aminoácidos, que se mostraram úteis na detecção de íons trivalentes (Al3+, Ga3+, Fe3+ e Cr3+) e também Hg2+. No terceiro capítulo apresentaremos um derivado de pireno seletivo ao Hg2+ tanto em meio aquoso quanto orgânico. Nos três capítulos utilizamos da técnica de espectrofluorimetria como principal ferramenta de estudo e aplicação dos sistemas. Durante as caracterizações e investigações dos mecanismos de detecção, utilizamos de maneira integrada as técnicas de espectrofluorimetria resolvida no tempo, espectroscopia de absorção no UV-vis, RMN de 1H e 13C e espectrometria de massas. A união de técnicas espectroscópicas complementares nos permitiu a completa caracterização estrutural dos compostos sintetizados e também um maior aprofundamento das propostas dos mecanismo de detecção dos analitos. De modo geral, o trabalho aborda áreas distintas dentro da química e da física, resultando em um conjunto de interfaces científicas com bom entrelace. Serão discutidas estratégias de síntese orgânica, caracterizações fotofísicas, estudos de mecanismo de detecção e aplicação analítica para cada uma das moléculas apresentadas nesta tese. / The present work deals with the synthesis of fluorescent probes towards the detection and quantification of metal ions and anions of relevant toxicity for humans and the environment. We used as building blocks the fluorescent cores of fluorescein, coumarin and pyrene, to which were coupled structures capable to interact selectively with analytes. Due to the distinct characteristics of the probes, we split the work into three chapters where each will address a core class. In the first one, we will deal with two coumarin derivatives, where one is able to identify and quantify the fluoride anion, and other the copper (II) ion. At the second chapter, we will describe two fluorescein derivatives attached to amino acids, which proved useful in the detection of trivalent ions (Al3+, Ga3+, Fe3+ e Cr3+) and Hg2+. In the last chapter, we will introduce a derivative of pyrene selective to Hg2+ detection in both aqueous and organic solvents. In all the three chapters, the spectrofluorimetry technique was the primary tool of study and application of the systems. During the structural characterizations and mechanism investigations, we used also time resolved spectrofluorimetry, UV-Vis absorption spectroscopy, 1H and 13C NMR, and mass spectrometry. The integration of spectroscopic techniques allowed us to a complete structural characterization of the synthesized compounds and the discussion of detection mechanism proposals. In general, the work deals with different areas within the chemistry and physics, resulting in a set of interfaces with good scientific interlace. Strategies in organic synthesis, structural and photo-physics characterizations, detection mechanisms and analytical application were the objective and the achievement of the present thesis.

Cells have lesion bypass DNA polymerases (DNAPs), often in the Y-Family, which synthesize passed DNA damage. One class of Y-Family DNAPs includes hDNAP k, EcDNAP IV and SsDbh, which insert accurately opposite N2-dG adducts, including BP-N2-dG formed from benzo[a]pyrene (BP). Another class includes hDNAP h, EcDNAP V and SsDpo4, which insert accurately opposite UV-damage. For correct Watson-Crick pairing between BP-N2-dG and dCTP, the BP moiety must be in the minor groove. On the minor groove side of the active site, k/IV/Dbh-class DNAPs have large openings that accommodate the BP moiety. Primer extension assays with purified proteins show that DNAP IV correctly inserts dCTP opposite BP more than 10-fold faster than it mis-inserts dATP, dGTP, or dTTP. In contrast, h/V/Dpo4-class DNAPs have small active site openings, which cannot accommodate BP and lead to a distorted structure and increased mutagenesis; e.g., Dpo4 has dGTP and dATP insertion rates that are 10-fold greater than those of dCTP. The opening in Dpo4 is plugged and bulky, whereas DNAP IV has a relatively spacious cavity. Consistent with this model, mutants of Dpo4 with a larger opening insert up to 10-fold more accurately opposite BP-N2-dG. Near the active site, Dpo4 has a single non-covalent bridge (NCB) between the little finger domain and the thumb-palm-fingers domain. DNAP IV and Dbh have a second, distal NCB that is 8 angstroms away from the active site towards the 3' end of the template DNA. Dpo4 becomes nearly 5-fold more accurate when mutated to carry a distal NCB, suggesting that NCB's also help control mutagenesis. Lastly, the active site of Dpo4 has a cavity in the major groove side, which may allow base flipping and dGTP insertion opposite -BP, while k/IV/Dbh-type polymerases do not. When this cavity is plugged in Dpo4 by mutagenesis or the introduction of an N-clasp motif, dGTP rates increase by nearly 20-fold. In conclusion, this data suggests that three structural regions contribute to accurate dCTP insertion opposite BP-N2-dG by k/IV/Dbh-class DNAPs: a large opening on the minor groove side near the active site, a cavity on the major groove side, and the number of non-covalent bridges between the little finger domain and the thumb-palm-fingers domain.

Orientador: Arielle Cristina Arena / Resumo: Entre as substâncias com potencial de desregulação endócrina, destaca-se o Benzo(a)pireno (BaP), um poluente orgânico persistente e amplamente difundido no ambiente. É gerado pela combustão incompleta de compostos orgânicos e está presente na fumaça de cigarro, na exaustão de automóveis, em alimentos e água contaminados. Estudos demonstram que o BaP se acumula em órgãos vitais e reprodutores, incluindo o testículo, e pode interferir no processo de esteroidogênese, através da interação com a proteína StAR. Sabe-se que substâncias que atuam como desreguladores endócrinos (DEs) podem gerar prejuízos não somente no indivíduo exposto, mas também nas gerações subsequentes, via células germinativas. A exposição aos DEs torna-se mais relevante em períodos hormônio-dependentes, como a gestação, a infância e a peripuberdade, denominados de janelas críticas do desenvolvimento. Assim, torna-se fundamental a investigação da exposição ao BaP durante uma janela crítica do desenvolvimento (juvenil e peripuberdade) e avaliar quais são as repercussões disto na vida reprodutiva, bem como os possíveis impactos no desenvolvimento e reprodução da prole, via paterna. Para tal, 40 ratos machos Wistar no período juvenil (23 dias de idade) foram distribuídos em quatro grupos experimentais, sendo um controle (óleo de milho + DMSO); e três grupos que receberam diferentes doses de BaP: 0,1, 1,0 ou 10 μg/kg/dia. A exposição ao poluente ocorreu durante 31 dias consecutivos, do dia pós-natal (DPN) 23 ao 53,... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Among substances with potential for endocrine disruptor, benzo(a)pyrene (BaP), a persistent organic pollutant widely distributed in the environment, stands out. It is generated by the incomplete combustion of organic compounds and is present in cigarette smoke, exhaust from cars, contaminated food and water. Studies have shown that BaP accumulates in vital and reproductive organs, including the testis; and may interfere with the steroidogenesis process through interaction with the StAR protein. It is known that substances that act as endocrine-disrupting chemicals (EDCs) can generate damages not only in the exposed individual, but also in subsequent generations by germ cells. Exposure to EDCs becomes more relevant in hormone-dependent periods, such as gestation, childhood and peripuberty, called critical windows of development. Thus, it is essential to investigate exposure to BaP during the critical development window (juvenile and peripuberty) and to investigate the repercussions of this on reproductive life and the possible impacts on the development and reproduction of the offspring, paternal way. For this, 40 male Wistar rats were used in the juvenile period (23 days of age) and distributed into four experimental groups, one control (corn oil + DMSO); and three groups receiving different doses of BaP: 0.1, 1.0 or 10 μg/kg/ day. The exposure to pollutant occurred during 31 consecutive days, from the postnatal day (PND) 23 to 53, via oral (gavage). During the treatment, cli... (Complete abstract click electronic access below) / Mestre

O presente estudo teve como objetivo avaliar o perfil da molécula relacionada à inflamação (ICAM-1), citocinas e da atividade das NTPDases como potencial influência sobre a genotoxicicdade em trabalhadores expostos ocupacionalmente a HPA. Este estudo incluiu 45 taxistas e 40 indivíduos com atividades administrativas (não-expostos ocupacionalmente), ambos nãi fumantes. O monitoramento biológico foi realizado pela quantificação do 1-hidroxipireno (1-pireno OH) urinário. A expressão de ICAM-1 (CD54) em neutrófilos foi realizada por citometria de fluxo. O perfil de hidrólise das NTPDases em plaquetas foi determinada pelo método colorimétrico. Além disso, os níveis de malondialdeído no plasma (MDA), citoquinas inflamatórias (IL-1β, IL-6, IL-10, TNF-α e IFN-γ) e o dano ao DNA (ensaio cometa e do micronúcleo) foram também avaliados. Os resultados demonstraram que os níveis de 1-OH pireno foram significativamente aumentados nos motoristas de táxi em comparação com o grupo não exposto ocupacionamente (p <0.0001); também foi positivamente correlacionada com neutrófilos ICAM-1, níveis de MDA e biomarcadores de danos no DNA. A expressão de ICAM-1 em neutrófilos foi significativamente elevado em motoristas de táxi (p <0.05), bem como os níveis de MDA (p <0.01), sendo a última positivamente correlacionada com a % de DNA na Cauda e frequência de MN. Aumento da hidrólise de ATP e ADP forma encontrados nos taxistas. Concentrações dos marcadores pró-inflamatórios foram aumentadas e anti-inflamatórias (IL-10) diminuída no grupo exposto. Para o teste de ensaio de micronúcleos e cometa, houve aumento significativo em motoristas de táxi, inclusive depois da adição de enzimas de reparo. Correlações positivas foram encontradas entre IL-1β, IL-6, TNF-α, IFN-γ e preditores de danos no DNA (% de DNA na cauda e frequência de MN), enquanto que a IL-10 está negativamente correlacionada com os biomarcadores de lesão ao DNA. Em resumo, a exposição ocupacional à poluição do ar pode levar a anormalidade homeostática como potencial contribuição para o processo aterosclerótico. Este estudo mostrou também que a exposição crônica à poluição do ar pode causar danos no DNA relacionado com a peroxidação lipídica e processo inflamatório. / The present study aimed to evaluate the profile of inflammatory molecule (ICAM-1), cytokines and the NTPDases activity as potential influence on genotoxicity process in workers exposed occupationally to PAH. This study included 45 taxi drivers and 40 non-occupationally exposed subjects, both non smorkers. Biological monitoring was performed by quantification of urinary 1-hydroxypyrene (1-OH pyrene). The expression of ICAM-1 (CD54) in neutrophil was performed and the hydrolysis profile of the NTPDases in platelets was determined. Plasma malondialdehyde (MDA) levels, inflammatory cytokines and DNA damage (comet and micronucleus assays) were also evaluated. The results demonstrated that the 1-OH pyrene levels were significantly increased in taxi drivers (p<0.0001); were also positively correlated to neutrophil ICAM-1 expression, MDA levels and biomarkers of DNA damage. ICAM-1 expression in neutrophil was significantly elevated in taxi drivers (p<0.05), as well as MDA levels (p<0.01), being the last positively correlated with % Tail DNA and MN frequency. ATP and ADP hydrolysis was increased in taxi drivers. Pro-inflammatory markers concentrations were increased and anti-inflammatory (IL-10) was decreased in exposed group. For the comet assay and micronucleus test, increase was significant in taxi drivers, inclusive after repair enzymes. Positively correlations were found between IL-1β, IL-6, TNF-α, IFN-γ and predictors of DNA damage (%Tail DNA and MN frequency), while IL-10 is negatively correlated with the biomarkers of DNA lesion. In summary, occupational exposure to air pollution, especially to PAHs, may be related with homeostatic abnormality as potential contribute to atherosclerosis process. This study showed also that the chronic exposure to outdoor air pollution may cause DNA damage related with lipid peroxidation and inflammatory process.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Os hidrocarbonetos policíclicos aromáticos (HPA) constituem um grupo de poluentes ambientais persistentes são moléculas com dois ou mais anéis aromáticos condensados, pouco solúveis em água e estão presentes no ambiente como resultante de processos naturais e também de atividades antrópicas; desta forma, os HPA podem ser encontrados em diversas matrizes ambientais. No presente trabalho foram utilizados mexilhões da região de Búzios, no Estado do Rio de Janeiro. Esse organismo foi selecionado devido à facilidade de acumulação de HPA nos tecidos, decorrente das propriedades hidrofóbicas dos HPA. O presente projeto teve como objetivo estudar um novo material de limpeza capaz de minimizar os compostos interferentes da matriz. Os cartuchos de SPE Florisil 5 g, são convencionalmente usados na limpeza de amostras de organismos, porém para diminuir os custos foram testados outros materiais adsorventes que pudessem ser eficientes na remoção dos interferentes presentes nos tecidos de mexilhão. Sendo assim, na etapa de limpeza conhecida como clean-up, foi estudada a recuperação do pireno após a extração por micro-ondas através de duas abordagens diferentes; a) utilização de cartuchos de SPE comerciais de 5 g de Florisil; b) cartuchos preenchidos com argila comercial K-10 bentonite, simulando os cartuchos comerciais. A recuperação e eficiência dos procedimentos de limpeza foram testadas e comparadas. A clean-up com argila K-10 apresentou uma recuperação de até 77% de pireno, sendo eficiente na remoção de compostos de colesteróis; confirmando a eficiência do material escolhido para a limpeza da amostra. A técnica de Cromatografia Gasosa e detecção por Espectrometria de Massas (GC-MS) foi aplicada para identificação e quantificação do contaminante pireno no extrato finaa / Polycyclic aromatic hydrocarbons (PAH) are a group of persistent environmental pollutants are molecules containing two or more condensed aromatic rings, little soluble in water and are present in the environment as a result of natural processes and human activities; in this way, the HPA can be found in various environmental matrices. In this work we used mussels in Búzios, Rio de Janeiro State. That body was selected due to the ease of accumulation of HPA in the tissues, due to the hydrophobic properties of HPA. This project aimed to study a new cleaning material able to minimize interfering compounds of the array. The 5 g Florisil SPE cartridges, are conventionally used in the cleaning of samples of organisms, however for lower costs have been tested other adsorbent materials which could be effective in the removal of the present in the tissues of mussels interfering. Therefore, in step of cleaning known as clean-up, recovery of pyrene was studied after extraction by microwave through two different approaches; a) use of commercial SPE cartridges 5 g of Florisil; b) cartridges filled with K-10 clay bentonite commercial, simulating the commercial cartridges. Recovery and efficiency of cleaning procedures were tested and compared. The clean-up with K-10 clay presented a recovery of up to 77% of pyrene, being effective in removing compounds of cholesterols; confirming the efficiency of the chosen material for cleaning of the sample. The technique of gas chromatography and detection by mass spectrometry (GC-MS) was applied for identification and quantification of contaminant pyrene in the final extract

Exposure to polycyclic aromatic hydrocarbons (PAHs) such as benzo(a)pyrene are important risk factors for cancer. Three UDP-glucuronosyltransferases, UGT1A9, UGT1A10, and UGT2B7, have been shown to play an important role in the phase II metabolism of carcinogenic metabolites of BaP. Because UGT1A9 and UGT2B7 are well-expressed in digestive tract tissues including liver and colon, it is possible that genetic variations in either enzyme may play an important role in colon cancer risk. However, UGT1A10 is extrahepatic and is expressed in the oral cavity and the larynx; therefore, genetic variations in this enzyme may play an important role in risk for orolaryngeal cancer. This study examined UGT1A9-, UGT1A10-, and UGT2B7-specific sequences for polymorphisms that play a role in cancer susceptibility. For the UGT1A9 gene, two missense polymorphisms at codons 167 (Val>Ala) and 183 (Cys>Gly) were identified. A previously-reported missense polymorphism was identified for the UGT2B7 gene. To assess the potential role of UGT1A10 variants as a risk factor for orolaryngeal cancer, PCR-RFLP was used to identify UGT1A10 genotypes in DNA specimens isolated from 115 African American newly-diagnosed orolaryngeal cancer cases and 115 non-cancer controls individually matched by age and race. A significantly decreased risk for orolaryngeal cancer was observed for subjects possessing one or more UGT1A10139Lys alleles as determined by crude analysis or after logistic regression analysis adjusting for age, sex, smoking and alcohol consumption. These results strongly suggest that the UGT1A10139Lys polymorphism may play an important protective role in risk for orolaryngeal cancer. To determine whether the change in amino acid sequence at codon 183 results in aberrant UGT1A9 enzyme activity, functional characterization of the wild-type- and variant-encoded UGT1A9 isoforms was performed in vitro. Cell homogenates were prepared from UGT1A9-transfected HK293 cells and glucuronidation assays were performed against various carcinogens/carcinogen metabolites. A significant (p<0.001) 3- to 4-fold decrease in enzyme activity, determined by HPLC analysis, was observed for the UGT1A9183Gly variant as compared to its wild-type counterpart for all substrates analyzed. These results demonstrate that the UGT1A9 (Cys183Gly) polymorphism significantly alters UGT1A9 function and could potentially play an important role as risk modifier for digestive tract cancers.