title: Studies on the mercapturic acid pathway in the rabbit lens.
abstract: We have examined the mercapturic acid pathway of the cataractous rabbit lens following induction by naphthalene as an oxidative foreign substance. 1,2-Naphthoquinone, which is formed in the eye from naphthalene diol and other naphthalene derivatives by a combination of enzymic and non-enzymic reactions, readily oxidizes GSH and GSH S-transferase [EC 2.5.1.18] in the lens scavenging system. 1,2-Naphthoquinone appeared in the rabbit aqueous humor after 8 h, and showed a maximum level in the lens 24 h after naphthalene administration, with marked accumulation in the lens nucleus. At the same time, the GSH level and GSH S-transferase activity in the lens decreased after 4 h, and lens opacification appeared 7 days after naphthalene administration. Furthermore, we identified the naphthalene metabolite, N-acetyl-S-(1,2-dihydro-2-hydroxynaphthyl) cysteine, in the lens of rabbit after naphthalene administration and in an in vitro experiment on lens homogenate using gas chromatography-mass spectrometry (GC-MS). This compound is an intermediate of the mercapturic acid pathway, and indicates that naphthalene derivatives are metabolized through the mercapturic acid pathway which acts as a scavenging system in the lens.
authors.affiliation: Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Meijo University, Nagoya, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Iwata
authors.forename: T
authors.initials: T
authors.lastname: Maesato
mesh_terms: D000111:Acetylcysteine / Q000378:metabolism*; D000818:Animals; D001082:Aqueous Humor / Q000378:metabolism; D002386:Cataract / Q000378:metabolism*; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D005978:Glutathione / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D007908:Lens, Crystalline / Q000378:metabolism*; D009281:Naphthalenes / Q000378:metabolism; D009285:Naphthoquinones / Q000378:metabolism; D011817:Rabbits
chemical_list: D009281:Naphthalenes; D009285:Naphthoquinones; C031721:naphthalene; C040756:1,2-naphthoquinone; D005982:Glutathione Transferase; D005978:Glutathione; D000111:Acetylcysteine