1.Investigation of urinary pteridine levels as potential biomarkers for noninvasive diagnosis of cancer.
Gamagedara S1, Gibbons S, Ma Y. Clin Chim Acta. 2011 Jan 14;412(1-2):120-8. doi: 10.1016/j.cca.2010.09.015. Epub 2010 Sep 22.
BACKGROUND: Biomarkers are good potential tools for early cancer diagnosis. Here we have analyzed eight different pteridines in the urine samples of cancer patients and compared them with samples from healthy subjects. Pteridines are important cofactors in the process of cell metabolism, and they have recently become a focal point of cancer screening research because certain pteridine levels have been shown to reflect the presence of cancers.
2.[Time course of the content of folates and free amino acids in leaves of Pisum sativum L. after irradiation with ultraviolet C].
Stakhov LF, Ladygin VG, Stakhov LN. Izv Akad Nauk Ser Biol. 2005 Mar-Apr;(2):155-61.
The effect of irradiation with UV-C on the time course of the content of total folates and free amino acids in leaves of pea (Pisum sativum L.) cultivar Neistoshchimyi was studied. It was shown that photolysis of folates is a rapid response to exposure to ultraviolet, as a result of which the plant produces a stable compound, pterin-6-carboxylic acid, with a relative fluorescence quantum yield approximately 2.0 at 20 degrees C (total value, 0.58). Presumably, this compound may be involved in the pterin-mediated photosensitization of singlet oxygen production. The kinetics of changes in the composition of free amino acids after exposure to UV-C has been studied. Exposure to UV-C for 0.5 and 1min induced utilization of free amino acids, suggesting activation of the synthesis of hormones and alkaloids that may facilitate resistance to the stressor. Greater doses as a result of exposure to radiation for 10 and 40 min decreased the content of free hydrophobic amino acids.
3.Capillary electrophoresis of pterin derivatives responsible for the warning coloration of Heteroptera.
Krajíček J1, Kozlík P1, Exnerová A2, Stys P2, Bursová M3, Cabala R4, Bosáková Z5. J Chromatogr A. 2014 Apr 4;1336:94-100. doi: 10.1016/j.chroma.2014.02.019. Epub 2014 Feb 13.
A new capillary electrophoretic (CE) method has been developed for analysis of 10 selected derivatives of pterin that can occur in the integument (cuticle) of true bugs (Insecta: Hemiptera: Heteroptera), specifically L-sepiapterin, 7,8-dihydroxanthopterin, 6-biopterin, D-neopterin, pterin, isoxanthopterin, leucopterin, xanthopterin, erythropterin and pterin-6-carboxylic acid. Pterin derivatives are responsible for the characteristic warning coloration of some Heteroptera and other insects, signaling noxiousness or unpalatability and are used to discourage potential predators from attacking. Regression analysis defining the parameters significantly affecting CE separation was used to optimize the system (the background electrolyte (BGE) composition, pH value and applied voltage). The optimized separation conditions were as follows: BGE with composition 2 mmol L(-1) the disodium salt of ethylendiamintetraacetic acid, 100 mmol L(-1) tris(hydroxymethyl)aminomethane and 100 mmol L(-1) boric acid, pH 9.
4.Photodegradation of folate sensitized by riboflavin.
Scurachio RS1, Skibsted LH, Metzker G, Cardoso DR. Photochem Photobiol. 2011 Jul-Aug;87(4):840-5. doi: 10.1111/j.1751-1097.2011.00916.x. Epub 2011 Apr 6.
Folate is shown to react with singlet-excited state of riboflavin in a diffusion controlled reaction and with triplet-excited state of riboflavin in a somewhat slower reaction with (3)k(q) = 4.8 × 10(8) L mol(-1) s(-1) in aqueous phosphate buffer at pH 7.4, ionic strength of 0.2 mol L(-1), and 25°C. Singlet quenching is assigned as photo-induced reductive electron transfer from ground state folate to singlet-excited riboflavin, while triplet quenching is assigned as one-electron transfer rather than hydrogen atom transfer from folate to triplet-excited riboflavin, as the reaction quantum yield, φ = 0.32, is hardly influenced by solvent change from water to deuterium oxide, φ = 0.37. Cyclic voltammetry showed an irreversible two-electron anodic process for folate, E = 1.14 V versus NHE at a scan-rate of 50 mV s(-1), which appears to be kinetically controlled by the heterogeneous electron transfer from the substrates to the electrode. Main products of folate photooxidation sensitized by riboflavin were pterin-6-carboxylic acid and p-aminobenzoyl-L-glutamic acid as shown by liquid chromatographic ion-trap mass spectrometry (LC-IT-MS).