A6: DNA PHOTOCLEAVAGE & PHOTOINDUCED TOXICITY OF POLYCYCLIC AROMATIC HYDROCARBON

在这个项目中，光诱导的DNA裂解通过 环境重要致癌物质多环芳烃 (PAH)，并测试其对细菌细胞的遗传毒性 用可见光和UVA光照射不同种类的 将对具有生物重要性的化学物质进行调查。这个 致癌代谢产物7，8-二羟基-9，1-O-环氧基-7，8，9，1 0-四氢苯并[a]芘被发现在辐照时能裂解DNA 355 nm激光。我们的假设是，其他多环芳烃也可以裂解 光化学激发时的DNA和DNA的裂解可能是一个来源 有光毒性。 DNA光切割的研究将集中在各种多环芳烃上，特别是 硝基、羟基、甲基和氮杂衍生物及其代谢物 例如二元醇环氧化物和二酮。多环芳烃的光反应性 针对DNA裂解的衍生物将使用质粒DNA进行检测。 每种多环芳烃的50%DNA裂解的浓度(C50) 要下定决心。生物因素对光分裂的影响 重要的化学品、金属离子和辅酶(NADH、黄素)将 也要接受检查。化合物的遗传毒性和生态毒性 展示出清晰的能力，光切割DNA将是 在紫外光或紫外线照射下进行各种微生物生物测定 室外日光照射。生物检测包括测量 细菌总数、三磷酸腺苷和腺苷总量、DNA 浓度，异养活性，叶绿素a浓度， 微毒素。和Mutatox测试。一份与光毒性有关的档案 DNA光切割将会建立起来。最后，一个 各种敏化剂对光化学和微生物降解的影响 将研究多环芳烃的速率。将制定一项协议，以 提高多环芳烃的去除和解毒率。 最强的DNA光裂解化合物将被进一步使用 用于研究光解产物。两家公司的摄影产品 切割的DNA和多环芳烃将使用以下组合进行鉴定 分析技术：高效液相色谱法。LC-MS和核磁共振。机制，用于 光诱导的DNA切割将从结构中推断出来 摄影产品。活性氧和自由基团的参与 我们还将对自由基进行研究。结构活性-关系(SAR) 将使用50用于光切割和LC*/LOEC用于研究 光毒-V。

In this project the light-induced DNA cleavage by the environmentally important carcinogen polycyclic aromatic hydrocarbons (PAH) and test their genotoxicity toward bacteria cell upon irradiation with visible and UVA light in the presence of various biologically important chemicals will be investigated. The carcinogenic metabolite 7,8dihydroxy.9,1 O-epoxy-7,8,9,1 0-tetrahydrobenzo[a]pyrene is found to cleave DNA when irradiated with 355 nm laser light. Our hypothesis is that other PAHs can also cleave DNA when photoichemically excited and the DNA cleavage may be a source of phototoxicity. Studies of DNA photocleavage will focus on various PAHs, especially the nitro, hydroxy, methyl, and aza derivatives and their metabolites such as the diol epoxides and diones. Photoreactivity of PAH derivatives toward DNA cleavage will be examined using plasmid DNA. The concentration (C50) at which 50% of DNA cleavage for each PAH will be determined. The effect on the photocleavage by biologically important chemicals, metal ions and coenzymes (NADH, Flavin), will also be examined. Genotoxicity and ecotoxicity of compounds exhibiting clear ability, to cleave DNA photochermically will be evaluated with a variety of microbial bioassays upon UV-Iight or outdoor sun-light irradiation. The bioassays include measurements of total bacterial numbers, ATP and total adenylate concentrations, DNA concentration, heterotrophic activity, chlorophyll a concentration, Microtox. and Mutatox Tests. A profile that relates the photoxicity and DNA photocleavage will be established. Finally, the effect of a variety of sensitizers on the photochemical and microbial degradation rates of PAHs will be studied. A protocol will be established to enhance the removal and detoxification rates of PAHs. Compounds that are strongest DNA photocleavers will be used further for studying the photocleavage products. Photoproducts of both cleaved DNA and PAHs will be identified using a combination of analytical techniques: HPLC. LC-MS, and NMR. Mechanisms for the photoinduced DNA cleavage will be deduced from the structure Of the photoproducts. The involvement of active oxygen species and free radicals will also be studied. Structure Activity- Relationship (SAR) will be studied using the 50 for the photocleavage and LC*/LOEC for the phototoxicit-v.