3-(2,4-Dibromo­anilino)-2,2-dimethyl-2,3-dihydro­naphtho[1,2-b]furan-4,5-dione: a new substituted aryl­amino nor-β-lapachone derivative

The title compound, C20H15Br2NO3, shows the furan ring to adopt a half-chair conformation and the two ring systems to be approximately perpendicular [dihedral angle = 71.0 (2)°]. In the crystal structure, inter­molecular C—H⋯O contacts link the mol­ecules

Electrochemical determination of oncocalyxone A using an iron-phthalocyanine/iron-porphyrin modified glassy carbon electrode

The development of a highly sensitive voltammetric sensor for oncocalyxone A using a glassy carbon electrode modified with a bilayer iron(II) tetrasulfonated phthalocyanine (FeTSPc) and iron(III) tetra-(N-methyl-4-pyridyl)-porphyrin (FeT4MPyP) is described. The modified electrode showed high catalytic activity and stability for the oncocalyxone A reduction, provoking the anodic shift of the reduction peak potentials of ca. 30 mV and presenting much higher peak currents than those obtained on the bare GC electrode. A wide linear response range between 0.005-1.2 µmol L-1, with a sensitivity of 8.11 µA L µmol-1 and limits of detection (LOD) and quantification (LOQ) of 1.5 and 5 nmol L-1 were obtained with this sensor.Descreve-se, no presente trabalho, o desenvolvimento de um sensor voltamétrico altamente sensível para a oncocalixona A, utilizando-se eletrodo de carbono vítreo modificado com uma bi-camada de ftalocianina tetrassulfonada de ferro(II) (FeTSPc) e tetra-(N-metil-4-piridil)-porfirina de ferro(III) (FeT4MPyP). O eletrodo modificado apresentou alta atividade catalítica e estabilidade em relação à redução da oncocalixona, proporcionando deslocamento anódico de ca. de 30 mV e amplificação da corrente de pico, em relação a iguais parâmetros obtidos em eletrodo de carbono vítreo não modificado. Um ampla faixa linear de resposta entre 0.005-1.2 µmol L-1, com sensibilidade de 8.11 µA L µmol-1 e limites de detecção (LOD) e quantificação (LOQ) de 1.5 e 5 nmol L-1 foram obtidos, com o uso desse sensor.697703Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Chemoselective oxidation of benzophenazines by m-CPBA: n-oxidation vs. oxidative cleavage

Chemoselectivity is observed when a pyran-benzo[a]phenazine and a furan-benzo[a]phenazine from beta-lapachone and nor-beta-lapachone, respectively, were submitted to oxidation by m-CPBA. The pyran phenazine furnished mainly macrolactones, while the furan one led exclusively to a phenazine N-8 oxide. To understand this difference in reactivity, we synthesized a new furan phenazine, with the reactive double bond site less hindered than that of the derivative from nor-beta-lapachone. This furan phenazine, upon oxidation with m-CPBA, furnished mainly the expected macrolactone. These experimental results, along with preliminary analysis based on mechanical molecular calculations of the ground state of the substrates, allowed us to suggest that the observed chemoselectivity has a steric oxidant approach control origin, related to the presence of the geminal methyl groups in the phenazine structure. Several of the synthesized compounds are, herein, reported for the first time

Some Applications of Electrochemistry in Biomedical Chemistry. Emphasis on the Correlation of Electrochemical and Bioactive Properties

This review summarises some of the more relevant achievements in the correlation between electrochemical processes and parameters and bioactive properties, mainly related to cancer and tropical diseases. Despite the broad range of possibilities and the complexity of cell/tissue/extracell chemistry, it is possible to rationalise the role of electrochemistry in few basic theoretical frameworks, mainly, the one based on electron transfer-oxidative stress and in situ generation of toxic species, other than the reactive oxygen species; interaction with endobiotics, with emphasis on bioreductive alkylation and replacement of endobiotics with function in biological redox reactions. The use of electrochemical methods to obtain relevant informations about drugs' mechanism of action and analysis of cellular events is also presented. Electrochemical methods and/or parameters play essential but not absolute roles

DETERMINATION OF ADVANCED GLYCATION (AGEs) AND LIPOXIDATION (ALEs) END PRODUCTS IN FOODS AND BIOLOGICAL SYSTEMS: ADVANCES, CHALLENGES AND PERSPECTIVES

Advanced glycation (AGEs) and lipoxidation (ALEs) products are formed through specific condensation reactions between nucleophiles (amino groups of free amino acids or their residues in peptides, aminophospholipids or proteins) and electrophiles (carbonyls of reducing sugars, oxidized lipids or others) generating well-defined sets of covalent adducts. The ε-amino group of the lysine is the most reactive precursor in proteins and the primary target of carbohydrate attacks. AGEs/ALEs accumulation has consequences in the development of vascular, renal, neural and ocular complications, as well as in the triggering of inflammatory and neurodegenerative diseases. Therefore, AGEs/ALEs detection, quantification and, in some cases, the assessment of the extent of glycation in biomolecules of different matrices represent a factor of primary interest for science. Reliable analytical methods are thus required. Together with basic concepts, this review presents the main advances, challenges and prospects of research involving AGEs and ALEs in biological and food systems, exploring practical strategies to ensure greater reliability in the analysis of these compounds in different matrices