• 제목/요약/키워드: Adducts

검색결과 270건 처리시간 0.025초

BIOLOGICAL HUMAN MONITORING OF CARCINOGEN EXPOSURE: A NEW STRATEGY IN CANCER PREVENTION

  • Lee, Byung-Mu
    • Toxicological Research
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    • 제6권1호
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    • pp.61-61
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    • 1990

  • Human exposure to environmental carcinogens can be detected by a number of methods including immunoassay, $^{32}P$-postlabeling assay, and fluorescence technique. These assays have been applied to measure biological markers of carcinogen-adducts formed with macromolecules such as DNA, RNA and protein. In an attempt to investigate causal relation ships between carcinogen exposure and tumor formation, specific carcinogen-adducts have been quantitated from human tissues and body fluids of cancer patients, occupational workers heavily exposed to certain carcinogens, smokers and controls. Carcinogens studied for biological human monitoring include benzo(a)pyrene, aflatoxin B1, UV light, ethylene oxide, 8-methoxypsoralen, 4-aminobiphenyl, vinyl chloride, N-nitrosamine, cisplatin and other chemotherapeutic agents. Relevance of human monitoring for cancer research, progress in this field, methods to detect carcinogen-adducts are reviewed here. It is hoped that these approaches will be used for the risk assessment of carcinogen exposure, cancer etiology study and cancer prevention in humans.

Tropolone 類에 關한 硏究 (III) Dichloroketene과 Cyclopentadiene 類의 添加物의 構造와 그 反應機構 (Studies on Tropolones (Ⅲ) Structures and Reaction Mechanisms of the Adducts of Dichloroketene and Cyclopentadienes)

  • 심재후
    • 대한화학회지
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    • 제13권1호
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    • pp.89-95
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    • 1969

  • The structural investigations on the adducts, formed from dichloroketene with cyclopentadiene, methyl and ethylcyclopentadiene, have been carried out by means of infrared and nuclear magnetic resonance spectroscopy and also by their chemical behaviors. It was confirmed by this study that the adducts were formed by 1, 2-cycloaddition reaction and had the fundamental structure of bicyclo [3. 2. 0]-7,7-dichloro-2-heptene-6-one. These results were well agreed with the hypothesis that a diradical intermediate was formed as the first step in 1, 2-cycloaddition. The reaction mechanism for the process in which tropolones were formed from these adducts was also discussed.

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A Practical Synthesis of Morita-Baylis-Hillman Adducts of Aryl Vinyl Ketones Catalyzed by a Proton Donor

  • Kim, Sung-Hwan;Kim, Se-Hee;Lim, Cheol-Hee;Kim, Jae-Nyoung
    • Bulletin of the Korean Chemical Society
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    • 제33권6호
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    • pp.2023-2027
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    • 2012

  • An efficient and practical synthesis of MBH adducts of aryl vinyl ketones was developed using DABCO and 4-nitrophenol as a proton donor. Addition of a proton donor and the use of excess amounts (3.0 equiv) of aldehydes were highly beneficial for the yields of MBH adducts of aryl vinyl ketones.

  • https://doi.org/10.5012/bkcs.2012.33.6.2023 인용 PDF KSCI

The Molecular Mechanism of Safrole-induced DNA Adducts and its Role to Oral Carcinogenesis

  • Liu, Tsung-Yun
    • 한국환경성돌연변이발암원학회지
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    • 제23권3호
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    • pp.99-102
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    • 2003

  • IARC classified areca quid as a human carcinogen. Areca quid chewed in Taiwan includes Piper betle inflorescence, which contains high concentrations of safrole (15 mg/fresh weight). Safrole is a documented rodent hepatocarcinogen, and chewing areca quid may contribute to human exposure (420 $\mu$m in saliva). The carcinogenicity of safrole is mediated through 1'-hydroxysafrole formation, followed by sulfonation to an unstable sulfate that reacts to form DNA adducts. Using human liver microsomes and Escherichia coli membranes expressing bicistronic human P450s, CYP2E1 and CYP2C9 were identified as the main P450s involved in the activation of safrole. We have demonstrated the presence of stable safrole-dGMP adducts in human oral tissues following areca quid chewing using $^{32}$ P-postlabeling and HPLC mass spectrometry methods. By studying 88 subjects with a known AQ chewing history and 161 matched controls, we have demonstrated that the presence of safrole-DNA adducts in peripheral blood cells was correlated to AQ chewing, and CYP2E1 seemed to play an important role in the modulation of safrole-DNA adduct formation. We have also shown that safrole can form stable safrole-DNA adducts as well as oxidative damages in rodent liver. However, the stable safrole-DNA adducts may represent a more significant initial lesion as compared to the rapidly repaired safrole-induced 8-hydroxy-2'-deoxyguanosine. This oxidative DNA damage is mediated through the formation of hydoryxchavicol, the major safrole metabolite in human urine. Hydroxychavicol may have gone through two-electron oxidation to the o-quinone; then via one-electron reduction to semiquinone radicals to generate oxidative DNA damage. However, these reactive metabolites can be efficiently conjugated by GSH. These data suggest that safrole may contribute to the initiation of oral carcinogenesis through safrole-DNA adduct and not oxidative DNA damage. In addition, CYP2E1 may modulate this adduct formation.

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