Faculty of Health Sciences, Hokkaido University, Sapporo 060-0812, Japan.
Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
Anal Chem. 2022 Jun 21;94(24):8651-8658. doi: 10.1021/acs.analchem.2c00576. Epub 2022 May 23.
Ozone is a potent environmental oxidant with high chemical reactivity and is present in the ambient environment at a low level of a few tens of ppb. However, only limited information is known about low-level ozone's influence on the respiratory system. In the present study, we systematically investigated the degradation of 1-palmitoyl-2-oleoyl--glycero-3-phosphocholine (POPC), which is one of the major components of the pulmonary surfactant (PS), enabling breath function of the lung exposed to low ambient-level ozone (40 ± 10 ppb). Using the liquid chromatography-mass spectrometry technique combined with the Langmuir-Blodgett approach, we first tracked the degradation process of POPC molecules by determining the degradation products during exposure to the ambient environment. As a result, we found that the POPC molecules can be readily degraded from the C═C moiety in 45 min, yielding an aldehyde-type product of 1-palmitoyl-2-(9'-oxo-nonanoyl)--glycero-3-phosphocholine (POnPC) and a trace amount of an acid-type one of 1-palmitoyl-2-azelaoyl--glycero-3-phosphocholine (PAzPC), as well as a pair of secondary ozonide (SOZ) isomers. Furthermore, with prolonged exposure, the SOZ stayed constant but the yield of PAzPC significantly increased with the decrease in POnPC. The low-level ozone-induced oxidation mechanisms for unsaturated lipids are discussed based on the quantitative analyses of these experimental observations. The present results demonstrate that the ground-level ozone is strong enough to induce dramatic oxidation damage to the unsaturated lipids of the PS. These oxidized species may trigger the lung's inflammatory response and be used as biomarkers for oxidative stress and inflammation.
臭氧是一种具有高化学反应性的强效环境氧化剂，在环境中以几十 pptb 的低水平存在。然而，对于低水平臭氧对呼吸系统的影响，人们知之甚少。在本研究中，我们系统地研究了 1-棕榈酰-2-油酰基-甘油-3-磷酸胆碱（POPC）的降解，POPC 是肺表面活性剂（PS）的主要成分之一，使暴露于低环境水平臭氧（40 ± 10 ppb）下的肺发挥呼吸功能。我们使用液相色谱-质谱联用技术结合 Langmuir-Blodgett 方法，首先通过测定暴露于环境中时的降解产物来跟踪 POPC 分子的降解过程。结果表明，POPC 分子可以很容易地从 C═C 部分在 45 分钟内降解，生成醛型产物 1-棕榈酰-2-（9'-氧代壬酰基）-甘油-3-磷酸胆碱（POnPC）和痕量的酸型产物 1-棕榈酰-2-二十二酰基-甘油-3-磷酸胆碱（PAzPC），以及一对次级臭氧化物（SOZ）异构体。此外，随着暴露时间的延长，SOZ 保持不变，但 PAzPC 的产率随着 POnPC 的减少而显著增加。基于这些实验观察的定量分析，讨论了不饱和脂质的低水平臭氧诱导氧化机制。本研究结果表明，地面臭氧足以对 PS 的不饱和脂质引起剧烈氧化损伤。这些氧化产物可能引发肺部炎症反应，并可作为氧化应激和炎症的生物标志物。
