l-3-Hydroxykynurenine,
l-kynurenine,
trifluoroacetic acid (TFA), meta-phosphoric acid (mPA), potassium
hydrogenphosphate (K
2HPO
4),
sodium borohydride (NaBH
4),
5,5′-dithiobis-(2-nitrobenzoic acid) (DTNB),
tris(hydroxymethyl)aminomethane (Tris-HCl), cysteine, and oxidized
glutathione (GSSG) were purchased from the Sigma–Aldrich Chemical Co.
(St. Louis, MO).
d,
l-3-Hydroxykynurenine
O-β-
d-glucoside and
4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid
O-β-
d-glucoside were synthesized by the method of Manthey
and coworkers.
20 Glutathionyl-3-hydroxykynurenine
glucoside was synthesized by the method of Garner and
coworkers.
11 Ethanol, methanol, and acetonitrile were
purchased from Ajax (Auburn, NSW, Australia). Human lenses were
obtained postmortem from donor eyes at the National Disease Research
Interchange (Philadelphia, PA) and The Sydney Eye Hospital Lions Eye
Bank (Sydney, Australia). After removal, lenses were placed immediately
into sterile plastic screw-capped vials and kept at −20°C until
analyzed.