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Oxidative Stress in Vitiligo: Photo-Oxidation of Pterins Produces H(2)O(2) and pterin-6-carboxylic Acid

Oxidative Stress in Vitiligo: Photo-Oxidation of Pterins Produces H(2)O(2) and pterin-6-carboxylic Acid

Hartmut Rokos, Wayne D Beazley, Karin U Schallreuter

Biochem Biophys Res Commun. 2002 Apr 12;292(4):805-11.

PMID: 11944885

Abstract:

Patients with vitiligo accumulate millimolar levels of H(2)O(2) in their epidermis. The recycling process of (6R)-l-erythro-5,6,7,8-tetrahydrobiopterin in these patients is disrupted due to deactivation of 4a-OH-BH(4) dehydratase by H(2)O(2). The H(2)O(2) oxidation products 6- and 7-biopterin lead to the characteristic fluorescence of the affected skin upon Wood's light examination (UVA 351 nm). Here we report for the first time the presence and accumulation of pterin-6-carboxylic acid (P-6-COOH) in the epidermis of these patients. Exploring potential sources for P-6-COOH revealed that sepiapterin and 6-biopterin are readily photo-oxidised to P-6-COOH by UVA/UVB irradiation. Photolysis of sepiapterin and 6-biopterin produces stoichiometric H(2)O(2) under aerobic conditions, where O(2) is the electron acceptor, thus identifying an additional source for H(2)O(2) generation in vitiligo. A detailed analysis utilising UV/visible spectrophotometry, HPLC, TLC, and mass spectroscopy showed for sepiapterin direct oxidation to P-6-COOH, whereas 6-biopterin formed the intermediate 6-formylpterin (P-6-CHO) which is then further photo-oxidised to P-6-COOH.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP22150761	6-Biopterin		22150-76-1	Price

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