114-25-0Relevant articles and documents
Pyrolyzed photoresist carbon electrodes in aprotic solvent: Bilirubin electrochemistry and interaction with electrogenerated superoxide
Silvestrini,Mardegan,Kamath,Madou,Moretto,Passamonti,Scopece,Ugo
, p. 401 - 407 (2014)
Pyrolyzed photoresist carbon electrodes (PPCEs) are fabricated by the photopatterning of a negative tone epoxy-based photoresist, SU-8, through optimized standard UV photolithography. The electrochemical characteristics of PPCEs are investigated in dimethyl sulfoxide (DMSO), observing a wider accessible potential window and a smaller capacitance with respect to glassy carbon electrodes. PPCEs are used to study the cyclic voltammetric behavior of bilirubin (BR) in DMSO. Detailed information is obtained on the multiple steps involved both in the electrochemical oxidation and reduction of BR. Interesting points concerning the electrochemical oxidation of BR to biliverdin are clarified, identifying the formation of an intermediate whose fate depends on the time scale of the electrochemical experiment. PPCEs are also used to electrogenerate the superoxide anion O2-? in DMSO for studying possible reactions between BR and O2-?. The results obtained demonstrate that BR is an efficient superoxide scavenger and that a concentration 2 mM of BR is high enough to consume all the O2-? generated by oxygen reduction at the PPCE/DMSO interface.
Urinary excretion of α- and β-isomers of biliverdin-IX in humans
Hirota
, p. 481 - 484 (2007/10/03)
The distribution and relative proportions of the four isomers of α-, β-, γ- and δ-biliverdin-IX were investigated using urinary samples from seven healthy adults. The biliverdins from samples were adsorbed on talc, and the adsorbed biliverdins were then soaked in a solution of methanol and concentrated sulfuric acid for derivation to the dimethyl esters. The esters were passed to a reversed-phase cartridge for clean-up, then quantitated by HPLC on a reversed-phase column. The analyses revealed that the biliverdins in 24-h urine were comprised of 6.4 ± 2.5 nmol α- and 9.3 ± 5.4 nmol β-isomers. The HPLC analyses suggested the presence of a δ-isomer in a much smaller amount, but no γ-isomer was detected. The identifications of α- and β-isomers were performed with co-chromatography and absorption spectra.
On the Fate of Biliverdin-IIIα-dimethyl Ester Formed by Scrambling During Syntheses of Biliverdin-IXα-dimethyl Ester from Bilirubin
Krois, Daniel,Lehner, Harald
, p. 575 - 580 (2007/10/02)
In the preparations of biliverdin-IXα-dimethyl ester (2b) from bilirubin-IXα (1) the ratio of the XIIIα- and IIIα-isomers 3b and 4b, formed via intermolecular scrambling, should be unity.However, irrespective of the synthetic variant considered, the amount of 4b obtained usually is exceptionally low.This is partly ascribed to a consecutive reaction of 4b in acidic methanol affording the chiral diastereomeric bridged biliverdins 5(a and b) and 6(a and b), respectively. - Keywords: Biliverdin-IIIα; Bridged biliverdins; Bilatrienes