In VivoEvidence for Compromised Phenylalanine Metabolism in Vitiligo

Schallreuter, Karin U.; Zschiesche, M; Moore, Julia; Panske, Angela; Hibberts, Nigel A.; Herrmann, Falko H.; Metelmann, H.‐R.; Sawatzki, J.

doi:10.1006/bbrc.1997.8107

Cited by 56 publications

(37 citation statements)

References 16 publications

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“…One of the most important pterins is (6R)-L-erythro- 5,6,7, which is the essential cofactor for various intracellular metabolic steps including the hydroxylation of the amino acids L-phenylalanine, L-tyrosine and L-tryptophan. In addition, nitric oxide synthase requires 6BH 4 for activity.…”

Section: What Are Pterins?mentioning

confidence: 99%

“…Based on the characteristic fluorescence of the skin in patients with vitiligo, the presence of the entire 6BH 4 de novo synthesis/recycling mechanism was identified in both epidermal melanocytes and keratinocytes [3,7]. To date, all enzyme activities and expression of specific mRNA involved in this biosynthetic pathway have been demonstrated.…”

Section: What Are Pterins?mentioning

confidence: 99%

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Successful Treatment of Oxidative Stress in Vitiligo

Schallreuter¹

1999

Skin Pharmacol Physiol

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Patients with vitiligo have low catalase levels in their involved and uninvolved epidermis in association with high levels of hydrogen peroxide (H₂O₂). H₂O₂ has been confirmed for the first time in vivo using Fourier Transform Raman spectroscopy. A topical substitution with a UVB-activated pseudocatalase can successfully remove epidermal H₂O₂ in vitiligo. This approach leads to recovery of the oxidative damage in the epidermis and remarkable repigmentation in this disorder.

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Section: What Are Pterins?mentioning

confidence: 99%

Section: What Are Pterins?mentioning

confidence: 99%

Successful Treatment of Oxidative Stress in Vitiligo

Schallreuter¹

1999

Skin Pharmacol Physiol

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“…In addition to liver and kidneys, significant PAH activity and expressions were also reported in pancreas tissue [36,38]. Keratinocytes were suggested as potential target for PKU gene therapy [39] and claimed to contain intact PAH metabolism [40], however with our assay no PAH activity or protein was detected in these cells.…”

Section: Discussionmentioning

confidence: 69%

Quantification of phenylalanine hydroxylase activity by isotope-dilution liquid chromatography–electrospray ionization tandem mass spectrometry

Heintz

Troxler

Martı́nez

et al. 2012

Molecular Genetics and Metabolism

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BACKGROUND: Residual phenylalanine hydroxylase (PAH) activity is the key determinant for the phenotype severity in phenylketonuria (PKU) patients and correlates with the patient's genotype. Activity of in vitro expressed mutant PAH may predict the patient's phenotype and response to tetrahydrobiopterin (BH(4)), the cofactor of PAH. METHODS: A robust LC-ESI-MSMS PAH assay for the quantification of phenylalanine and tyrosine was developed. We measured PAH activity a) of the PAH mutations p.Y417C, p.I65T, p.R261Q, p.E280A, p.R158Q, p.R408W, and p.E390G expressed in eukaryotic COS-1 cells; b) in different cell lines (e.g. Huh-7, Hep3B); and c) in liver, brain, and kidney tissue from wild-type and PKU mice. RESULTS: The PAH assay was linear for phenylalanine and tyrosine (r(2) 0.99), with a detection limit of 105 nmol/L for Phe and 398 nmol/L for Tyr. Intra-assay and inter-assay coefficients of variation were <5.3% and <6.2%, respectively, for the p.R158Q variant in lower tyrosine range. Recovery of tyrosine was 100%. Compared to the wild-type enzyme, the highest PAH activity at standard conditions (1 mmol/L L-Phe; 200 mol/L BH(4)) was found for the mutant p.Y417C (76%), followed by p.E390G (54%), p.R261Q (43%), p.I65T (33%), p.E280A (15%), p.R158Q (5%), and p.R408W (2%). A relative high PAH activity was found in kidney (33% of the liver activity), but none in brain. CONCLUSIONS: This novel method is highly sensitive, specific, reproducible, and efficient, allowing the quantification of PAH activity in different cells or tissue extracts using minimum amounts of samples under standardized conditions

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“…Cucumis melo exctract is a rich antioxidant that naturally contain a high superoxide dismutase activity [52].…”

Section: Cucumis Melomentioning

confidence: 99%

Antioxidants

Eken¹

2015

Pigmentary Disorders

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Antioxidants are chemicals that can prevent oxidative stress or slow cell damage. Natural antioxidants are mainly found in fruits and vegetables, marine plants, and some seafood that eat marine plants. Most commonly used antioxidants in vitiligo are; vitamin C, vitamin E, ginkgo biloba, vitamin A, polypodium leucotomas extract, polyunsatured fatty acids, quercetin flavonoids, tea polyphenols, soy isoflavones, resveratrol, curcumin, capsaicin, gluthathione, alpha lipoic acid, phenylalanine, cucumis melo, minerals.

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In VivoEvidence for Compromised Phenylalanine Metabolism in Vitiligo

Cited by 56 publications

References 16 publications

Successful Treatment of Oxidative Stress in Vitiligo

Successful Treatment of Oxidative Stress in Vitiligo

Quantification of phenylalanine hydroxylase activity by isotope-dilution liquid chromatography–electrospray ionization tandem mass spectrometry

Antioxidants

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