Treatment of melasma has remained a hottopic in dermatology because of its resistance totherapy and high recurrence rate. For many yearshydroquinone was the foundation of melasmatreatment, but its use has been limited during theseyears due to a number of adverse events, suchas skin irritation, hyper and hypo pigmentation,nail discoloration, conjunctival melanosis andochronosis. Furthermore hydr...

In Europe, hydroquinone is a forbidden cosmetic ingredient. It is, however, still abundantly used because of its effective skin-whitening properties. The question arises as to whether the quantities of hydroquinone used become systemically available and may cause damage to human health. Dermal absorption studies can provide this information. In the EU, dermal absorption has to be assessed in vi...

the electrochemical preparation of poly-n-methylpyrrole (pmpy) coated platinum electrode in chloroform in the presence of tetrabutylammonium perchlorate, hexafluorophosphate, hydrogensulphate, periodate and iodide as supporting electrolytes was performed. the influence of electrosynthesis method, dopant anion type and operation temperature on electrochemical behavior of polymer were demonstrate...

Polychlorinated biphenyls (PCBs) can be oxygenated to form very reactive hydroquinone and quinone products. A guiding hypothesis in the PCB research community is that some of the detrimental health effects of some PCBs are a consequence of these oxygenated forms undergoing one-electron oxidation or reduction, generating semiquinone radicals (SQ (*-)). These radicals can enter into a futile redo...

We used natural spline (NS) models to investigate nonlinear relationships between levels of benzene metabolites (E,E-muconic acid, S-phenylmercapturic acid, phenol, hydroquinone, and catechol) and benzene exposure among 386 exposed and control workers in Tianjin, China. After adjusting for background levels (estimated from the 60 control subjects with the lowest benzene exposures), expected mea...

The metabolism of two of benzene's phenolic metabolites, phenol and hydroquinone, by peroxidase enzymes has been studied in detail. Studies employing horseradish peroxidase and human myeloperoxidase have shown that in the presence of hydrogen peroxide phenol is converted to 4,4'-diphenoquinone and other covalent binding metabolites, whereas hydroquinone is converted solely to 1,4-benzoquinone. ...

A simple, fast method of high-performance liquid chromatography for the determination and quantification of arbutin and hydroquinone in many different raw materials was developed and validated. The optimum conditions for the separation and detection of these two constituents were achieved on a LiChro-CARD 125-4 Superspher®100 RP-18 column with the water-methanol (gradient elution) mobile phase ...

IPI-504, a water-soluble ansamycin analogue currently being investigated in clinical trials, is a potent inhibitor of the protein chaperone heat shock protein 90 (Hsp90). Inhibition of Hsp90 by IPI-504 triggers the degradation of important oncogenic client proteins. In cells, the free base of IPI-504 hydroquinone exists in a dynamic redox equilibrium with its corresponding quinone (17-AAG); the...

The flavin-protein interactions and flavoprotein-ligand interactions in the general acyl-CoA dehydrogenase from pig liver were studied by measuring the absorption spectra and circular dichroism spectra of the oxidized enzyme and complexes of the oxidized enzyme with enoyl-CoA products and two dead-end inhibitors. The spectra indicate that the flavin is slightly reoriented upon ligand binding an...