Identification of a Novel Fluorophore, Xanthurenic Acid 8- O -β- D -glucoside in Human Brunescent Cataract

Autor: Amane Inoue, Kanako Ando, Yutaka Shirao, Dorairajan Balasubramanian, Etsuko Shirao
Rok vydání: 2001
Předmět:
Zdroj: Experimental Eye Research. 73:421-431
ISSN: 0014-4835
DOI: 10.1006/exer.2001.1051
Popis: We have identified the chemical structure of a novel protein-unbound fluorescent glucoside (Fl-Glc), found to be far more abundant in the human brunescent cataractous lens nuclei than in non-brunescent ones. Our earlier experiments showed that long-term incubation of the protein-free filtrate of non-brunescent cataractous nuclei generated increasing amounts of a particular yet to be characterized fluorophore (Fl-X). High performance liquid chromatography (HPLC) analyses revealed Fl-X and Fl-Glc to be identical. HPLC-electrospray ionization-mass spectrometry (HPLC-ESI-MS) disclosed the molecular weights (MW) of Fl-X and its beta-glucosidase-digest (Fl-X-aglycon) to be 367 and 205, respectively. Fl-X-aglycon and authentic xanthurenic acid (MW = 205) not only eluted at exactly the same retention time on HPLC but also revealed their protonated ions at the same m/z of 206.1 by positive ion analysis on HPLC-ESI-MS. These results suggest that Fl-X ( = Fl-Glc) is a beta-glucoside of xanthurenic acid. Fl-Glc was finally identified as xanthurenic acid 8- O -beta- D -glucoside because the retention times of both completely agreed with three kinds of HPLC conditions.
Databáze: OpenAIRE
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