Photochemistry and photophysics of UV filter decomposition products in the human eye

The human eye is photoprotected by molecular UV filters which consist of low-molecular weight compounds in the lens that absorb UV light in the 300-400 nm spectral region.  The UV filters decompose to give a mixture of products, which can include kynurenine yellow (KNY) and kynurenic acid (KNA) from the UV filter kynurenine.  These compounds have only been found in very small or negligible concentrations in the human lens which may indicate that they are much more chemically or photochemically active than the original UV filters.

Graphical abstract for C2PP25357GIn this work, Yuri Tsentalovich and colleagues from Russia, Switzerland and The Netherlands investigated the photochemistry and photophysics of neutral aqueous solutions KNY and KNA using time-resolved optical spectroscopy.  Their work has shown that both of these molecules are significantly more photoactive and photostable than the parent UV filter.  These species and their products may react with the protein environment in the lens and could contribute to the development of oxidative stress conditions – a main factor in the development of cataract.

Read this article for free until the 8th February 2013:

Photochemistry of aqueous solutions of kynurenic acid and kynurenine yellow, Ekaterina A. Zelentsova, Peter S. Sherin, Olga A. Snytnikova, Robert Kaptein, Eric Vauthey and Yuri P. Tsentalovich, Photochem. Photobiol. Sci., 2013, DOI: 10.1039/C2PP25357G

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