Identification of the new UV filter compound cysteine-L-3-hydroxykynurenine O-beta-d-glucoside in human lenses.

UV filters protect the human lens and retina from UV light-induced damage. Here, we report the identification of a new UV filter, cysteine-l-3-hydroxykynurenine O-beta-d-glucoside, which is present in older normal human lenses. Its structure was confirmed by independent synthesis.

A fluorescence-based assay for indoleamine 2,3-dioxygenase.

A rapid and sensitive fluorescence-based bioassay for determination of indoleamine 2,3-dioxygenase (IDO) activity has been developed. This assay relies on the quantification of the amount of kynurenine produced in the assay medium by fluorescence and complements the standard absorbance and high-performance liquid chromatography (HPLC) assay methods. The fluorescence method has limits of detection similar to those of the standard assay methods.

Lenticular levels of amino acids and free UV filters differ significantly between normals and cataract patients.

Purpose: To determine the levels of free UV filters and selected amino acids in cataract lenses compared with normal lenses.

Methods: Indian cataract lenses (n=39) and normal lenses (n=6) were examined by HPLC to quantify levels of UV filter compounds, the UV filter precursor amino acid tryptophan (Trp), as well as tyrosine (Tyr) and uric acid.

Results: The levels of the two major primate UV filters, 3-hydroxykynurenine glucoside (3OHKG) and 4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid glucoside (AHBG), in cataract lenses were markedly decreased compared with levels in normal lenses.