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Cyclic voltammetric and EPR spectroscopic studies of benzodiazepines: Loprazolam and flunitrazepam

Authordc.contributor.authorNúñez Vergara, Luis 
Authordc.contributor.authorBollo Dragnic, Soledad 
Authordc.contributor.authorOlea Azar, Claudio 
Authordc.contributor.authorNavarrete-Encina, Patricio 
Authordc.contributor.authorSquella Serrano, Juan 
Cita de ítemdc.identifier.citationJournal of Electroanalytical Chemistry, Volumen 436, Issue 1-2, 1997, Pages 227-238
Abstractdc.description.abstractThe present paper reports on the electrochemical characterization by cyclic voltammetry of two 1,4-benzodiazepines, loprazolam and flunitrazepam in protic, aprotic and mixed media. In protic media (ethanol + 15 mM citrate buffer pH 8.0) both drugs were irreversibly reduced at HDME involving 4 electrons to give the hydroxylamine derivative. In the optimal mixed media conditions (DMF + 15 mM citrate buffer, 0.1 M TBAI, pH 9.0) and in aprotic media (DMF + 0.1 M TBAI), the one-electron reduction product corresponding to the nitro radical anion was successfully isolated for both drugs. In both electrolytic media (mixed or aprotic media) loprazolam was reduced at less negative potentials compared with flunitrazepam. Radical decay follows second order kinetics. In mixed media the following second order decay constants and half-lives (for a 5 mM concentration) were found: k(2) = 1573.6 +/- 35.7 l mol(-1) s(-1), t(1/2) = 0.13 s for flunitrazepam and k(2) = 455.5 +/- 16.6 l mol(-1) s(-1) t(1/2) = 0.44 s, for loprazolam. EPR spectra recorded in situ using DMF as an electrolytic solvent showed well-resolved spectra, confirming the reduction of both benzodiazepine derivatives to their corresponding nitro radical anions. The experimental and the simulated hyperfine constant values obtained by INDO calculations are in agreement. The magnitude of such hyperfine splitting constants permits us to conclude that these radical anions are mainly restricted to the benzene ring of the molecules.
Type of licensedc.rightsAttribution-NonCommercial-NoDerivs 3.0 Chile
Link to Licensedc.rights.uri
Sourcedc.sourceJournal of Electroanalytical Chemistry
Keywordsdc.subjectAnalytical chemistry
Keywordsdc.subjectChemical Engineering (all)
Títulodc.titleCyclic voltammetric and EPR spectroscopic studies of benzodiazepines: Loprazolam and flunitrazepam
Document typedc.typeArtículo de revista
Indexationuchile.indexArtículo de publicación SCOPUS

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Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivs 3.0 Chile