PHOTOCHEMISTRY AND BIOACTIVITY OF POLYCYCLIC AROMATIC HYDROCARBONS ADSORBED ON

吸附多环芳烃的光化学和生物活性

• 批准号: 7381558
• 负责人: SILVINA FIORESSI
• 金额: $ 8.45万
• 依托单位: UNIVERSITY OF PUERTO RICO
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7381558
• 关键词: PHOTOCHEMISTRY; BIOACTIVITY; POLYCYCLIC; AROMATIC; HYDROCARBONS

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs are ubiquitous atmospheric pollutants associated to the airborne particulate matter. Many of them present mutagenic activity and their presence in the atmosphere have been related with an increase in cancer incidence, particularly lung cancer. PAHs can be formed from any incomplete combustion process under oxygen deficient conditions of fossil fuels or any organic material. Human exposure to PAHs can occur through several pathways, these include inhalation from ambient air and internal absorption from food and water. During their residence in the atmosphere, PAHs &re susceptible to thermal and photochemical reactions with air or with other copollutants. For example, PAHs can react with nitrogen oxides to form mono- and di-nitro derivatives. These reactions are of particular interest because both types of contaminants are often emitted simultaneously from combustion sources and could react directly at the point of emission. Moreover, the nitro-PAHs are often much more potent carcinogens than the parent PAHs. In the presence of oxygen, PAHs react photochemically forming oxidized derivatives like diones, alcohols and poly-alcohols, among others. These oxygenated PAHs are in many cases, more harmful to human health than their precursors. In this project we propose to study the photochemistry, spectroscopy and mutagenic properties of nitrated and oxygenated derivatives of polycyclic aromatic hydrocarbons adsorbed on model surfaces and in solution with the purpose of providing information on its ultimate environmental and biomedical fate. Benzo[e]pyrene (BeP) and benzo[a]pyrene (BaP) will be studied as representative PAHs, whereas silica gel and alumina will be selected as models of the respirable particles. The specific aims pursued can be summarized as the followings: 1. Determine the experimental conditions that favor the transformation of the PAHs to the corresponding nitrated and oxygenated derivatives. The effect of the physical and chemical properties of the adsorbent (substrate composition, surface loading, water content, presence of acidic and basic additives) on the photo reactivity of BeP and BaP towards nitrogen oxides and oxygen will be studied. Thermal reactions that may occur on the surface will be also explored. 2. Isolate and characterize the major products (particularly nitro-PAHs and oxygenated derivatives of the PAHs) adsorbed on silica gel and alumina and also in solution using HPLC coupled with MS and UVvisible absorption detection. Establish a possible photo degradation mechanism for the products formation adsorbed on the different surfaces and compare it with the photochemical behavior in solution. 3. Investigate the photophysical properties of adsorbed PAH's derivatives and study the interactions between the PAH and its microenvironment because these will influence its reactivity. Spectroscopic techniques such as UV-visible spectroscopy, fluorescence, laser flash photolysis and electron spin resonance will be used to achieve this aim. 4. Generate enough amounts of the major products to test their toxicological properties. The optimal conditions to produce the PAH's derivatives determined in aim 1 will be reproduced at semi-preparative scale to obtain significant amounts of the products. These will be purified chromatographically and collected in the appropriate solvent for further analysis of their mutagenicity. 5. Evaluate the mutagenic properties of the nitrated and oxygenated derivatives produced by reaction of BeP and BaP with nitrogen oxides and oxygen under simulated atmospheric conditions. The bacterial mutagenic activity of the isolated products will be determined by the Ames Salmonella typhimurium assay. This will help to establish if atmospheric reactions with nitrogen oxides and oxygen increase the toxicity of PAHs and to establish a realistic risk assessment for the human exposition to these pollutants and the biomedical consequences.

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。多环芳烃（PAHs）和硝基多环芳烃是大气颗粒物中普遍存在的污染物。其中许多物质具有诱变活性，它们在大气中的存在与癌症发病率的增加有关，特别是肺癌。多环芳烃可以由化石燃料或任何有机材料在缺氧条件下的任何不完全燃烧过程形成。人类暴露于多环芳烃可以通过几种途径发生，这些途径包括从环境空气中吸入和从食物和水中内部吸收。多环芳烃在大气中停留期间，易与空气或其他共污染物发生热反应和光化学反应。例如，多环芳烃可以与氮氧化物反应形成单硝基和二硝基衍生物。这些反应特别令人感兴趣，因为这两种类型的污染物通常同时从燃烧源排放，并且可以在排放点直接反应。此外，硝基多环芳烃往往是比母体多环芳烃更强的致癌物。在氧气存在的情况下，多环芳烃发生光化学反应，形成氧化衍生物，如二酮、醇和多元醇等。在许多情况下，这些含氧多环芳烃比其前体对人类健康的危害更大。在这个项目中，我们建议研究的硝化和氧化衍生物的多环芳烃吸附在模型表面和溶液中的光化学，光谱和诱变性能，其最终的环境和生物医学命运的目的提供信息。苯并[e]芘（BeP）和苯并[a]芘（BaP）将作为代表性的多环芳烃进行研究，而硅胶和氧化铝将被选为可吸入颗粒物的模型。所追求的具体目标可概括如下：1.确定有利于多环芳烃转化为相应的硝化和氧化衍生物的实验条件。将研究吸附剂的物理和化学性质（基质组成、表面负载、水含量、酸性和碱性添加剂的存在）对BeP和BaP对氮氧化物和氧气的光反应性的影响。还将探索可能发生在表面上的热反应。 2.分离和表征的主要产品（特别是硝基多环芳烃和多环芳烃的含氧衍生物）吸附在硅胶和氧化铝，也在溶液中使用HPLC结合MS和紫外可见吸收检测。建立了吸附在不同表面上的产物形成的可能的光降解机理，并与溶液中的光化学行为进行了比较。 3.研究吸附的PAH衍生物的物理化学性质，并研究PAH与其微环境之间的相互作用，因为这些都会影响其反应性。光谱技术，如紫外可见光谱、荧光、激光闪光光解和电子自旋共振将用于实现这一目标。 4.生产足够数量的主要产品以测试其毒理学特性。在目标1中确定的生产PAH衍生物的最佳条件将在半制备规模下重现，以获得大量的产物。这些将通过色谱法纯化，并收集在适当的溶剂中，用于进一步分析其致突变性。 5.在模拟大气条件下，评价BeP和BaP与氮氧化物和氧气反应产生的硝化和氧化衍生物的致突变性。分离产物的细菌致突变活性将通过艾姆斯鼠伤寒沙门氏菌试验测定。这将有助于确定大气与氮氧化物和氧气的反应是否会增加多环芳烃的毒性，并为人类暴露于这些污染物及其生物医学后果建立现实的风险评估。