A6: DNA PHOTOCLEAVAGE & PHOTOINDUCED TOXICITY OF POLYCYCLIC AROMATIC HYDROCARBON

在这个项目中， 环境重要致癌物多环芳烃 (PAH)并测试其对细菌细胞的遗传毒性， 在存在各种紫外线和可见光的情况下， 将研究生物学上重要的化学物质。 的 致癌代谢物7，8二羟基.9，1 O-环氧-7，8，9，1 发现0-四氢苯并[a]芘在用 355 nm激光。 我们的假设是其他的多环芳烃也可以裂解 当光化学激发时DNA和DNA切割可能是一个来源， 光毒性。 DNA光裂解的研究将集中在各种多环芳烃，特别是 硝基、羟基、甲基和氮杂衍生物及其代谢物 例如二醇环氧化物和二酮。 PAH的光反应性 将使用质粒DNA检查朝向DNA切割的衍生物。 每种PAH发生50% DNA裂解的浓度（C50） 被确定。 生物活性物质对光裂解的影响 重要的化学物质，金属离子和辅酶（NADH，黄素），将 也要检查。 化合物的遗传毒性和生态毒性 显示出明确的能力，光化学切割DNA将是 在紫外光下用各种微生物生物测定法进行评价，或 室外阳光照射。 生物测定包括测量 细菌总数、ATP和总腺苷酸浓度、DNA 浓度、异养活性、叶绿素a浓度、 微生物毒素。 Mutatox测试 一个与光毒性有关的特征 并且将建立DNA光切割。 最后，A的效果 各种敏化剂对光化学和微生物降解的影响 将研究多环芳烃的含量。 将制定一项方案， 提高多环芳烃的去除率和解毒率。 作为最强的DNA光切割剂的化合物将被进一步使用 用于研究光裂解产物。 两者的光产物 切割的DNA和多环芳烃将使用以下组合进行鉴定： 分析技术：HPLC。 LC-MS和NMR。 机制 光诱导的DNA切割将从结构推导出的 照片产品 活性氧和自由基的参与 还将研究自由基。 构效关系（SAR） 将使用50进行光裂解研究，使用LC*/LOEC进行 光毒性-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.