A irradiação de alimentos já foi aprovada e vem sendo utilizada em diversos países para aplicações e finalidades de uma ampla variedade de alimentos. Seus benefícios abrangem o aumento do prazo de validade, melhoria de higiene dos alimentos e consequentemente menor deterioração e perdas se comparado com alimentos que não sofrem radiação. Além disto, os alimentos após irradiados apresentam-se seguros em termos nutritivos e de redução de patógenos. Porém, alimentos que contem de médio a alto teor de gordura induzem a formação de um subproduto denominado 2-Alcilciclobutanonas, a qual sabemos que parte destes compostos ingeridos são normalmente excretados através das fezes, porém parte permanece depositada nos tecidos adiposos. Trabalhos realizados com estes compostos anteriormente apresentaram efeitos citotóxicos e genotóxicos em células de cólon. Desta forma, o objetivo do presente trabalho foi investigar os efeitos citotóxicos realizados em testes de viabilidade celular, testes genotóxicos em micronúcleo e testes mutagênicos com a técnica de Ames em condições experimentais in vitro dos compostos 2-dDCB e 2-tDCB. Para isso, o fígado foi o órgão de escolha para avaliar os possíveis efeitos destes compostos, uma vez que este órgão é geralmente acometido pelo acumulo de gordura. Foram utilizadas três linhagens hepáticas: HepG2, BRL3A e HTC. A análise dos resultados da viabilidade celular, revelou que as 2-dDCBs apresentaram discreto efeito citotóxico na concentração de 500 μM e as 2-tDCBs apresentaram danos baixos a partir de 100 μM e maiores em 500 μM, mostrando ser dose dependentes. Nos resultados de mutagenicidade, os compostos não apresentaram quaisquer efeitos mutagênicos nas concentrações e doses utilizadas, detectados pelo teste de Ames. Por fim, o ensaio de micronúcleo correspondeu às expectativas não demonstrando efeitos genotóxicos na linhagem, doses e tempos testados. Com base nos resultados atingidos, as 2 ACBs podem ser consumidas com relativa segurança, sob a ótica de possíveis efeitos mutagênicos e genotóxicos nas concentrações avaliadas. / Food irradiation has already been approved and has been used in several countries for applications and purposes of a wide variety of foods. Its benefits include increased shelf life, improved food hygiene and consequently less deterioration and losses compared to foods that do not undergo into radiation. In addition, food after irradiation is safe in terms of nutrients and pathogen reduction. However, foods that contain medium to high fat levels, induce the formation of a by-product called 2-Alkylcyclobutanones, which we know that part of these ingested compounds are normally excreted through the feces, but part remains deposited in the adipose tissues. Work performed with these compounds previously showed cytotoxic and genotoxic effects on colon cells. Thus, the objective of the present work was to investigate the cytotoxic effects performed in cell viability tests, genotoxic tests in micronucleus and mutagenic tests with Ames technique under in vitro experimental conditions of 2-dDCB and 2-tDCB compounds. Hence, the liver was the chosen organ to evaluate the possible effects of these compounds, since this organ is usually affected by accumulation of fat. Three hepatic cell lines were used: HepG2, BRL3A and HTC. Analysis of the cell viability results revealed that the 2-dDCBs presented a discrete cytotoxic effect at the concentration of 500 μM and the 2-tDCBs presented low damages from 100 μM and larger at 500 μM, showing to be dose dependent. In the mutagenicity results, the compounds did not show any mutagenic effects at the concentrations and doses used, detected by the Ames test. Finally, the micronucleus test corresponded to expectations demonstrating no genotoxic effects in the cell line, doses and times tested. Based on the results achieved, the 2 ACBs can be consumed with relative safety, from the perspective of possible mutagenic and genotoxic effects in the evaluated concentrations.

A irradiação de alimentos já foi aprovada e vem sendo utilizada em diversos países para aplicações e finalidades de uma ampla variedade de alimentos. Seus benefícios abrangem o aumento do prazo de validade, melhoria de higiene dos alimentos e consequentemente menor deterioração e perdas se comparado com alimentos que não sofrem radiação. Além disto, os alimentos após irradiados apresentam-se seguros em termos nutritivos e de redução de patógenos. Porém, alimentos que contem de médio a alto teor de gordura induzem a formação de um subproduto denominado 2-Alcilciclobutanonas, a qual sabemos que parte destes compostos ingeridos são normalmente excretados através das fezes, porém parte permanece depositada nos tecidos adiposos. Trabalhos realizados com estes compostos anteriormente apresentaram efeitos citotóxicos e genotóxicos em células de cólon. Desta forma, o objetivo do presente trabalho foi investigar os efeitos citotóxicos realizados em testes de viabilidade celular, testes genotóxicos em micronúcleo e testes mutagênicos com a técnica de Ames em condições experimentais in vitro dos compostos 2-dDCB e 2-tDCB. Para isso, o fígado foi o órgão de escolha para avaliar os possíveis efeitos destes compostos, uma vez que este órgão é geralmente acometido pelo acumulo de gordura. Foram utilizadas três linhagens hepáticas: HepG2, BRL3A e HTC. A análise dos resultados da viabilidade celular, revelou que as 2-dDCBs apresentaram discreto efeito citotóxico na concentração de 500 μM e as 2-tDCBs apresentaram danos baixos a partir de 100 μM e maiores em 500 μM, mostrando ser dose dependentes. Nos resultados de mutagenicidade, os compostos não apresentaram quaisquer efeitos mutagênicos nas concentrações e doses utilizadas, detectados pelo teste de Ames. Por fim, o ensaio de micronúcleo correspondeu às expectativas não demonstrando efeitos genotóxicos na linhagem, doses e tempos testados. Com base nos resultados atingidos, as 2 ACBs podem ser consumidas com relativa segurança, sob a ótica de possíveis efeitos mutagênicos e genotóxicos nas concentrações avaliadas. / Food irradiation has already been approved and has been used in several countries for applications and purposes of a wide variety of foods. Its benefits include increased shelf life, improved food hygiene and consequently less deterioration and losses compared to foods that do not undergo into radiation. In addition, food after irradiation is safe in terms of nutrients and pathogen reduction. However, foods that contain medium to high fat levels, induce the formation of a by-product called 2-Alkylcyclobutanones, which we know that part of these ingested compounds are normally excreted through the feces, but part remains deposited in the adipose tissues. Work performed with these compounds previously showed cytotoxic and genotoxic effects on colon cells. Thus, the objective of the present work was to investigate the cytotoxic effects performed in cell viability tests, genotoxic tests in micronucleus and mutagenic tests with Ames technique under in vitro experimental conditions of 2-dDCB and 2-tDCB compounds. Hence, the liver was the chosen organ to evaluate the possible effects of these compounds, since this organ is usually affected by accumulation of fat. Three hepatic cell lines were used: HepG2, BRL3A and HTC. Analysis of the cell viability results revealed that the 2-dDCBs presented a discrete cytotoxic effect at the concentration of 500 μM and the 2-tDCBs presented low damages from 100 μM and larger at 500 μM, showing to be dose dependent. In the mutagenicity results, the compounds did not show any mutagenic effects at the concentrations and doses used, detected by the Ames test. Finally, the micronucleus test corresponded to expectations demonstrating no genotoxic effects in the cell line, doses and times tested. Based on the results achieved, the 2 ACBs can be consumed with relative safety, from the perspective of possible mutagenic and genotoxic effects in the evaluated concentrations.

Doctor of Philosophy / Department of Animal Sciences and Industry / J. Scott Smith / The effect of fat level and antioxidant Origanox on the formation of 2-dodecylcylobutanone (2-DCB) was investigated in fresh irradiated ground beef patties. Patties containing 15% and 25% fat were irradiated by electron beam at 1, 2, 3, and 4.5 kGy. Ground beef patties with 0.08% Origanox were gamma irradiated at 3.0 kGy. Commercially available irradiated ground beef with different fat levels was analyzed in order to estimate dose absorbed by these samples. The 2-DCB was extracted by Supercritical fluid extraction (SFE) and analyzed by gas chromatography-mass spectrometry (GC-MS). The concentration of 2-DCB increased linearly with dose with no significant difference in 2-DCB concentrations between the two fat levels. The estimated doses applied to the commercial samples ranged between 1.38 kGy and 1.55 kGy. Origanox did not affect the concentration of 2-DCB. Mutagenicity of 2-DCB was evaluated by the Ames assay using five standard Salmonella tester strains with S9 enzyme activation. The Ames assay did not show a mutagenic effect of 2-DCB, including samples incubated with S9. Acute toxicity of 2-DCB was evaluated by the Microtox acute toxicity system and compared with cyclohexanone and 2-nonenal (both GRAS additives). The toxicity of 2-DCB was between that of cyclohexanone and 2-nonenal while the maximum toxic effect elicited by 2-DCB was the least of the three compounds. Metabolism of 2-DCB was investigated in Female Sprague-Dawley rats. Hexane extracts of feces and fat were analyzed by GC-MS. Urine with and without added β-glucuronidase, was monitored for glucuronide complexes by hexane extraction GC-MS. The total amount of 2-DCB recovered in feces was 1.78 ± 0.63 mg over five days, about 3-11% of the total 2-DCB administered. The total amount recovered in fat was 0.08 ± 0.01 mg which was approximately 0.33% of the total 2-DCB administered. No metabolites were recovered in any of the urine extracts.