ABSTRACT
Pressure-assisted CE (PACE) was applied to determine the previously inaccessible complete set of pK values for folic acid and eight related multiprotic compounds. PACE allowed the determination of all acidity macroconstants at low (Subject(s)
Electrophoresis, Capillary/methods
, Folic Acid/chemistry
, Methotrexate/chemistry
, Pteridines/chemistry
, Folic Acid/radiation effects
, Hydrogen-Ion Concentration
, Magnetic Resonance Spectroscopy
, Methotrexate/radiation effects
, Osmolar Concentration
, Photochemistry
, Potentiometry/methods
, Pressure
, Pteridines/radiation effects
, Spectrophotometry, Ultraviolet
ABSTRACT
Halyomorpha brevis (Heteroptera: Pentatomidae) produces adults with different color patterns, most noticeable in the sternum. The color, ranging from ivory to red, depends on the extent of the accumulation of red pigment. The present work investigated the effects of photoperiod, temperature and aging on the pigmentation. The red pigment was identified as erythropterin by comparing the Rf with standard pteridines in paper chromatography in three solvent systems. Erythropterin was found in all organs, red or light red. Uric acid was detected prominently in ivory or light red sternum. A negative correlation was found between the extent of red pigmentation and that of uric acid content. The relative proportion of males and females with a red sternum progressively increased as they aged from day 0 to day 20 after adult emergence, particularly in males reared under a long day (non-diapausing). In males, an age-dependent decrease in red pigmentation was observed in the gastric ceca and tracheae. The sternum was lighter in short-day adults (diapausing) than that in non-diapausing adults at the same age, and the latter never achieved the intense red color. The possible functions of pteridines are discussed.
Subject(s)
Aging/physiology , Heteroptera/radiation effects , Photoperiod , Pigmentation/radiation effects , Pteridines/metabolism , Temperature , Animals , Female , Heteroptera/metabolism , Light , Male , Pteridines/radiation effectsABSTRACT
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.
Subject(s)
Biopterins/analogs & derivatives , Epidermis/metabolism , Hydrogen Peroxide/metabolism , Oxidative Stress , Pteridines/metabolism , Pterins/metabolism , Vitiligo/metabolism , Biopterins/chemistry , Biopterins/metabolism , Biopterins/radiation effects , Catalase/metabolism , Catalase/pharmacology , Catalase/radiation effects , Chromatography, High Pressure Liquid , Chromatography, Thin Layer , Epidermis/chemistry , Epidermis/drug effects , Humans , Hydrogen Peroxide/analysis , Hydrogen Peroxide/chemistry , Oxidation-Reduction/radiation effects , Oxygen/chemistry , Photochemistry , Pteridines/analysis , Pteridines/chemistry , Pteridines/radiation effects , Pterins/radiation effects , Ultraviolet Rays , Vitiligo/drug therapyABSTRACT
A method is presented for the successful decontamination of sparingly soluble pteridine derivatives by microwave irradiation. The method is nondestructive, rapid and effective in eliminating contamination.
