83-07-8Relevant articles and documents
N-demethylation of N-methyl-4-aminoantipyrine, the main metabolite of metamizole
Bachmann, Fabio,Duthaler, Urs,Rudin, Deborah,Kr?henbühl, Stephan,Haschke, Manuel
, p. 172 - 180 (2018)
Metamizole is an old analgesic used frequently in some countries. Active metabolites of metamizole are the non-enzymatically generated N-methyl-4-aminoantipyrine (4-MAA) and its demethylation product 4-aminoantipyrine (4-AA). Previous studies suggested that 4-MAA demethylation can be performed by hepatic cytochrome P450 (CYP) 3A4, but the possible contribution of other CYPs remains unclear. Using human liver microsomes (HLM), liver homogenate and HepaRG cells, we could confirm 4-MAA demethylation by CYPs. Based on CYP induction (HepaRG cells) and CYP inhibition (HLM) we could identify CYP2B6, 2C8, 2C9 and 3A4 as major contributors to 4-MAA demethylation. The 4-MAA demethylation rate by HLM was 280 pmol/mg protein/h, too low to account for in vivo 4-MAA demethylation in humans. Since peroxidases can perform N-demethylation, we investigated horseradish peroxidase and human myeloperoxidase (MPO). Horse radish peroxidase efficiently demethylated 4-MAA, depending on the hydrogen peroxide concentration. This was also true for MPO; this reaction was saturable with a Km of 22.5 μM and a maximal velocity of 14 nmol/min/mg protein. Calculation of the entire body MPO capacity revealed that the demethylation capacity by granulocyte/granulocyte precursors was approximately 600 times higher than the liver capacity and could account for 4-MAA demethylation in humans. 4-MAA demethylation could also be demonstrated in MPO-expressing granulocyte precursor cells (HL-60). In conclusion, 4-MAA can be demethylated in the liver by several CYPs, but hepatic metabolism cannot fully explain 4-MAA demethylation in humans. The current study suggests that the major part of 4-MAA is demethylated by circulating granulocytes and granulocyte precursors in bone marrow.
Photocatalytic hydrogenation of nitroarenes: supporting effect of CoOx on TiO2 nanoparticles
Amanchi, Srinivasa Rao,Ashok Kumar,Lakshminarayana, Bhairi,Satyanarayana,Subrahmanyam
, p. 748 - 754 (2019/01/10)
Cobalt oxide visible light-active photo-catalysts supported on TiO2 nanoparticles with varying amount of cobalt oxide [3% CoOx/TiO2 (A), 4% CoOx/TiO2 (B), 5% CoOx/TiO2 (C)] were synthesized by solid-state method followed by calcination. The as-synthesized catalysts were characterized by various techniques such as powder XRD, TEM, EDX, UV-Vis-DRS and XPS analysis. The photocatalytic activity of the as-synthesized materials was studied for the reduction of nitroarenes to the corresponding amines using hydrazine monohydrate as the reductant. Cobalt(ii) oxide is responsible for the reduction of nitroarenes and then, cobalt(iii) is reduced back to the original compound by hydrazine hydrate, thus ascertaining the catalytic nature of this hydrogenation process. XPS suggests the presence of Co(ii) in CoOx/TiO2.
Cu2+-selective colorimetric signaling by sequential hydrolysis and oxidative coupling of a Schiff base
Hong, Ja Min,Kim, Hong Yeong,Park, Hyunji,Chang, Suk-Kyu
, p. 6782 - 6785 (2016/09/09)
A new Cu2+-selective probe was developed based on the Cu2+-induced sequential hydrolysis and oxidative coupling reactions of 4-aminoantipyrine-appended 8-hydroxyquinoline derivative 1. Cu2+-assisted hydrolysis of the enamine moiety of Schiff base 1 afforded its constituents, 4-aminoantipyrine and 8-hydroxyquinoline-2-carboxaldehyde. The Cu2+-induced oxidative coupling between these in situ generated compounds afforded a quinoneimine dye. Prominent naked-eye-detectable selective signaling of Cu2+ions, assisted by EDTA, was realized through a color change from faint yellow to pink with a detection limit of 1.81 × 10?6M.