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Hydrophilic interaction liquid chromatographic analysis of aminohydroxyphenylalanines from melanin pigments
Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of clinical chemistry.
Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of clinical chemistry.
Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of clinical chemistry.
2007 (English)In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1163, no 1-2, 70-79 p.Article in journal (Refereed) Published
Abstract [en]

Malignant melanomas are more often seen in subjects with light colored skin who tan poorly than in persons who tan more rapidly. This has been attributed to the structure of their pigment, pheomelanin, which differs markedly from the eumelanin of persons with darker skin. To study the hydrolysis products of pheomelanin pigments a new method was developed for analysis of 4-amino-3-hydroxyphenylalanine (4-AHP) and 3-amino-4-hydroxyphenylalanine (3-AHP). Pheomelanin samples were hydrolyzed and extracted with solid-phase extraction columns using strong cation-exchange (SCX) cartridges. Separation of 4-AHP and 3-AHP was achieved on a ZIC-HILIC column (150 mm × 2.1 mm I.D.) with a mobile phase consisting of acetonitrile:0.1 M ammonium acetate buffer, pH 4.5 (82:18, v/v). Detection was performed with an electrochemical detector at +400 mV. Run time was 30 min. The limits of detection were 73 pg and 51 pg for 4-AHP and 3-AHP respectively, using 2 μl injections. Good linearity was found within the range 0.05-5.0 μg/ml. Absolute recovery was 70% and relative recovery was 100%. The AHPs were stable for 1 year in the hydrolyzed samples, for 4 days in the eluates from solid-phase sorbents stored in the refrigerator, and for 2 days diluted with mobile phase and stored in the autosampler at 10 °C. The within-day imprecision was <5% and the between-day imprecision was <7% for the two analytes. The method, applied to the analysis of pheomelanin in urine from human melanoma patients, allows the analysis of 30 samples in one set and is suitable for routine work with human hair and melanoma cells. By using the ZIC-HILIC stationary phase, ion-pairing reagents could be avoided, which makes the method suitable to further analysis of degradation products from pheomelanins using mass spectrometric detection. © 2007 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
2007. Vol. 1163, no 1-2, 70-79 p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-39471DOI: 10.1016/j.chroma.2007.06.007Local ID: 48765OAI: oai:DiVA.org:liu-39471DiVA: diva2:260320
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13Bibliographically approved
In thesis
1. Pheomelanin markers in melanoma with reference to their excretion into urine
Open this publication in new window or tab >>Pheomelanin markers in melanoma with reference to their excretion into urine
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Skin pigmentation is an important issue in most cultures. Until recently we have not understood the most important elements of pigmentation regarding detailed chemical structure. The synthesis of melanin is very complex, and although core enzymes, other important proteins, and parts of the melanin structure have been identified much information in this context awaits disclosure.

The function of the melanocyte and the deposition of melanin pigments into the keratinocytes are very important in the protection against UV light. Melanin pigments consist of high-molecular structures often described as brown to black eumelanin and yellow to red pheomelanin. Eumelanin is photoprotective, whereas pheomelanin is believed to be carcinogenic after UV radiation. There is strong evidence that people of fair complexion with freckles who tan poorly are at higher risk of developing melanoma. These people have a higher pheomelanin to eumelanin ratio in their skin.

Melanoma, one of the most widely spread cancers, is derived from melanocytes. There is accumulating evidence that pigment constitution is highly involved in the development of melanoma. We found that patients with advanced melanoma secrete substantial amounts of pigment structures into the urine, in particular those with diffuse melanosis. In subsequently performed experiments we purified these pigments and subjected the product to chemical degradation by either hydrogen peroxide oxidation or hydriodic hydrolysis. Several new chromatographic methods were developed for the structural analysis of these products. Structural analysis of new chromatographic peaks was performed. In conclusion, complex pheomelanin structures as well as low molecular weight pigments and free benzothiazoles have been identified in the urine of patients with melanoma and diffuse melanosis.

The present thesis provides new insight into melanogenesis and melanoma progression. This opens the doorway to further approaches to the investigation of melanins and can help to understand fundamental problems about the structure and biosynthesis of natural melanins.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2009. 67 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1143
Keyword
Pheomelanin, melanoma, benzothiazole, aminohydroxyphenylalanine, diffuse melanosis, HILIC
National Category
Other Clinical Medicine
Identifiers
urn:nbn:se:liu:diva-21486 (URN)978-91-7393-566-1 (ISBN)
Public defence
2009-10-23, Berzeliussalen, Hälsouniversitet, Campus US, Linköpings Universitet, Linköping, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2009-10-12 Created: 2009-10-02 Last updated: 2010-01-14Bibliographically approved

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Nezirevic Dernroth, DzenetaÅrstrand, KerstinKågedal, Bertil

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