Pulse radiolysis and cyclic voltammetry studies of redox properties of phenothiazine radicals

Madej, Edyta; Wardman, Peter

doi:10.1016/j.radphyschem.2006.01.007

Cited by 18 publications

(15 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As the delay time of EC/DESI-MS (i.e., the time interval between the onset of the electrochemical oxidation and the detection of the product ions by MS) for 5 μl/min flow rate was approximately 0.25 min, the lifetime of the chlorpromazine radical cation is estimated to be around 15 seconds, under the experimental conditions that was used in our experiment. This estimated life time of the chlorpromazine radical cation is in line with the previous report [46]. In Fig.…”

Section: Resultssupporting

confidence: 92%

“…It was proposed [33, 45, 46] that chlorpromazine can easily undergo oxidation in acid medium, in which a one e − oxidation process leads to the formation of a radical cation intermediate. It is known that, while the radical cation of phenothiazine is comparably stable, the radical cations of the substituted phenothiazines are believed to be unstable and could further react with solvent to give rise to sulfoxide [47].…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Investigation of some biologically relevant redox reactions using electrochemical mass spectrometry interfaced by desorption electrospray ionization

et al. 2012

View full text Add to dashboard Cite

Recently we have shown that, as a versatile ionization technique, desorption electrospray ionization (DESI) can serve as a useful interface to combine electrochemistry (EC) with mass spectrometry (MS). In this study, the EC/DESI-MS method has been further applied to investigate some aqueous phase redox reactions of biological significance, including the reduction of peptide disulfide bonds and nitroaromatics as well as the oxidation of phenothiazines. It was found that knotted/enclosed disulfide bonds in the peptides apamin and endothelin could be electrochemically cleaved. Subsequent tandem MS analysis of the resulting reduced peptide ions using collision-induced dissociation (CID) and electron-capture dissociation (ECD) gave rise to extensive fragment ions, providing a fast protocol for sequencing peptides with complicated disulfide bond linkages. Flunitrazepam and clonazepam, a class of nitroaromatic drugs, are known to undergo reduction into amines which was proposed to involve nitroso and N-hydroxyl intermediates. Now in this study, these corresponding intermediate ions were successfully intercepted and their structures were confirmed by CID. This provides mass spectrometric evidence for the mechanism of the nitro to amine conversion process during nitroreduction, an important redox reaction involved in carcinogenesis. In addition, the well-known oxidation reaction of chlorpromazine was also examined. The putative transient one-electron transfer product, the chlorpromazine radical cation (m/z 318), was captured by MS, for the first time, and its structure was also verified by CID. In addition to these observations, some features of the DESI-interfaced electrochemical mass spectrometry were discussed, such as simple instrumentation and the lack of background signal. These results further demonstrate the feasibility of EC/DESI-MS for the study of the biology-relevant redox chemistry and would find applications in proteomics and drug development research.

show abstract

Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Investigation of some biologically relevant redox reactions using electrochemical mass spectrometry interfaced by desorption electrospray ionization

et al. 2012

View full text Add to dashboard Cite

show abstract

“…However, at low oxygen concentrations, no molecular oxygen is available for the consecutive reaction after the production of LPZ· + . Therefore, the lifetimes of both 3 LPZ* and LPZ· + increase and there should be enough time to see its absorption, considering that the lifetime of LPZ· + is over a few milliseconds under anaerobic conditions . The absorption at 566 nm observed for LPZ· + (Fig.…”

Section: Resultsmentioning

confidence: 95%

Photooxidation Mechanism of Levomepromazine in Different Solvents

Piñero-Santiago

García

Lhiaubet‐Vallet

et al. 2013

Photochem & Photobiology

View full text Add to dashboard Cite

Unwanted photoinduced responses are well-known adverse effects of most promazine drugs, including levomepromazine (LPZ, Levoprome ® or Nozinan ® ). This drug is indicated in psychiatry primarily for the treatment of schizophrenia and other schizoaffective disorders. Levomepromazine's particular sedative properties make it especially fit for use in psychiatric intensive care. Nevertheless, it is photolabile under UV-A and UV-B light in aerobic conditions resulting in the formation of its sulfoxide. The LPZ photochemistry in acetonitrile (MeCN) is completely different from that in methanol (MeOH) and phosphate buffer solutions (PBS, pH = 7.4). The major photoproduct in PBS and MeOH under aerobic conditions is levomepromazine sulfoxide (LPZSO), although the amount is considerably higher in the aqueous environment. The corresponding main photoproduct in MeCN could not be characterized. The destruction quantum yields of LPZ in PBS, MeOH and MeCN are 0.13, 0.02 and <10 À3 , respectively. It is further demonstrated that LPZSO does not form by the reaction of singlet oxygen with ground-state LPZ. This oxidation product is actually produced by the reaction of the cation radical of LPZ (LPZÁ + ) with molecular oxygen. This cation radical in turn, is produced by an electron transfer process between the 3 LPZ* and ground-state molecular oxygen.

show abstract

“…More recent methods include spectrophotometric [8,13], polarography [14], voltammetry [14,15], potentiometry [16], high-performance liquid chromatography (HPLC) [17], spectrofluorimetry [18], capillary electrophoresis [19], flow injection analysis [20], etc.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical preparation of a molecularly imprinted polypyrrole modified pencil graphite electrode for the determination of phenothiazine in model and real biological samples

Nezhadali

Rouki

Nezhadali

2015

Talanta

View full text Add to dashboard Cite

Pulse radiolysis and cyclic voltammetry studies of redox properties of phenothiazine radicals

Cited by 18 publications

References 29 publications

Investigation of some biologically relevant redox reactions using electrochemical mass spectrometry interfaced by desorption electrospray ionization

Investigation of some biologically relevant redox reactions using electrochemical mass spectrometry interfaced by desorption electrospray ionization

Photooxidation Mechanism of Levomepromazine in Different Solvents

Electrochemical preparation of a molecularly imprinted polypyrrole modified pencil graphite electrode for the determination of phenothiazine in model and real biological samples

Contact Info

Product

Resources

About