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In Vivo Assessment of Alveolar Macrophage Efferocytosis Following Ozone Exposure
Published on: October 22, 2019
How phenol and alpha-tocopherol react with ambient ozone at gas/liquid interfaces.
Shinichi Enami1, Michael R Hoffmann, A J Colussi
1W. M. Keck Laboratories, California Institute of Technology, Pasadena, California 91125, USA.
The Journal of Physical Chemistry. A
|May 28, 2009
Summary
Alpha-tocopherol (alpha-TOH) reacts rapidly with ozone (O3) on microdroplet surfaces, forming novel adducts. This reaction mechanism differs from simple phenols and has implications for atmospheric chemistry.
Area of Science:
- Atmospheric Chemistry
- Oxidative Stress
- Analytical Chemistry
Background:
- Alpha-tocopherol (alpha-TOH), a form of Vitamin E, is known for its antioxidant properties, particularly free radical scavenging.
- Phenols can react with various reactive species, but their interaction with ozone (O3) is less understood.
- Understanding reactions of atmospheric pollutants with biologically relevant molecules is crucial for public health.
Purpose of the Study:
- To investigate the reaction mechanism between alpha-tocopherol and ozone (O3) at the gas/liquid interface.
- To characterize the products formed from the reaction of alpha-TOH with O3.
- To compare the reactivity of alpha-TOH with a prototype phenolate towards O3.
Main Methods:
- Utilized inert solvent microdroplets to study reactions at the gas/liquid interface.
- Employed online thermospray ionization mass spectrometry for product detection and characterization.
- Investigated reaction kinetics by varying pH and ozone concentration.
Main Results:
- Alpha-tocopherol (alpha-TOH) reacts with ozone (O3) on microdroplet surfaces in less than 1 millisecond, forming persistent alpha-TO-O(n)(-) adducts (n=1-4).
- The reaction occurs at the gas/liquid interface, evidenced by pH dependence and faster rates compared to bulk reactions.
- Identified specific adducts: alpha-TO-O(-) as a chroman-6-ol (4a, 8a)-ene oxide, alpha-TO-O(2)(-) as an endoperoxide, and alpha-TO-O(3)(-) as a secondary ozonide.
Conclusions:
- Alpha-tocopherol's reaction with ozone differs significantly from simple phenolates, which undergo electron transfer.
- The formation of persistent ozonide adducts suggests a novel atmospheric degradation pathway for substituted phenols.
- These findings have implications for understanding the atmospheric chemistry of aerosols and their impact on respiratory health.
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