Comparison of free non-tryptophan fluorescent substances in water-soluble fraction of brunescent and non-brunescent human cataract
Iwase, T.; Shirao, E.; Shirao, Y.; Matsukawa, S.; Fukuda, R.
Nippon Ganka Gakkai Zasshi 100(5): 369-375
1996
ISSN/ISBN: 0029-0203 PMID: 8651055 Document Number: 458078
We compared the concentrations of protein-unbound non-tryptophan fluorescent substances in the water-soluble fraction between non-brunescent (NBr) and brunescent (Br) human cataractous lens nuclei. Lens nuclei (NBr, 22 eyes: Br, 9 eyes) from non-diabetic patients, obtained by extracapsular cataract extraction, were individually homogenized and centrifuged. The supernatants were subsequently ultra-dialyzed and assessed by high pressure liquid chromatography. 3-Hydroxykynurenine-O-beta-glucoside (3-HKG) as well as an unidentified fluorescent substance was detected. While the concentrations of the former substance did not significantly differ between the NBr and the Br. nuclei (NBr, 0.55 +- 0.49 mu-mol/g wet weight : Br, 0.90 +- 0.64 mu-mol/g wet weight; p gt 0.1), the concentration of the latter substance was significantly greater in the Br nuclei than in the NBr nuclei (NBr, 2.2 times 10-3 +- 5.4 times 10-3 AU/g wet weight: Br, 1.4 times 10-5 +- 1.1 times 10-5 AU/g wet weight; AU : area unit, p lt 0.01). An incubation of the dialysate with beta-glucosidase eliminated the peak corresponding to the latter substance. These results suggest that an unidentified protein-unbound fluorescent substance, which is presumably a beta-glucoside, in the lens nuclei is related to the coloration of human lens nuclei.