Characterization and reactivity of photodimers of dihydroneopterin and dihydrobiopterin.

Abstract

7,8-Dihydrobiopterin (H(2)Bip) and 7,8-dihydroneopterin (H(2)Nep) belong to a class of heterocyclic compounds present in a wide range of living systems. H(2)Bip accumulates in the skin of patients suffering from vitiligo, whereas H(2)Nep is secreted by human macrophages when the cellular immune system is activated. We have investigated the photochemical reactivity of both compounds upon UV-A irradiation (320-400 nm), the chemical structures of the products and their thermal stability. The study was performed in neutral aqueous solutions. The reactions were followed by UV/Visible spectrophotometry and HPLC and the products were analyzed by means of electrospray ionization mass spectrometry and (1)H-NMR. Excitation of H(2)Bip and H(2)Nep leads to the formation, in each case, of two main isomeric dimers. The latter compounds undergo a thermal process that may consist in a retro [2 + 2]-cycloaddition and hydrolysis to yield the reactant (H(2)Bip or H(2)Nep) and a product that has incorporated a molecule of H(2)O.

• Authors: Mariana Vignoni, Carolina Lorente, Franco M Cabrerizo, Rosa Erra-Balsells, Esther Oliveros, Andrés H Thomas
• Journal: Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology (Photochem Photobiol Sci) Vol. 11 Issue 6 Pg. 979-87 (Jun 2012) ISSN: 1474-9092 [Electronic] England
• PMID: 22290295 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• 7,8-dihydroneopterin
• Biopterin
• Neopterin
• 7,8-dihydrobiopterin

Topics

• Biopterin (analogs & derivatives, chemistry)
• Chromatography, High Pressure Liquid
• Dimerization
• Humans
• Isomerism
• Macrophages (metabolism)
• Magnetic Resonance Spectroscopy
• Neopterin (analogs & derivatives, chemistry, metabolism)
• Photolysis
• Spectrometry, Mass, Electrospray Ionization
• Temperature
• Ultraviolet Rays