Article

The influence of hydroquinone on tyrosinase kinetics.

Gray Institute for Radiation Oncology & Biology, Department of Oncology, University of Oxford, Roosevelt Drive, Oxford OX3 7DQ, UK.
Bioorganic & medicinal chemistry (impact factor: 2.82). 05/2012; 20(14):4364-70. DOI:10.1016/j.bmc.2012.05.041
Source: PubMed

ABSTRACT In vitro studies, using combined spectrophotometry and oximetry together with hplc/ms examination of the products of tyrosinase action demonstrate that hydroquinone is not a primary substrate for the enzyme but is vicariously oxidised by a redox exchange mechanism in the presence of either catechol, L-3,4-dihydroxyphenylalanine or 4-ethylphenol. Secondary addition products formed in the presence of hydroquinone are shown to stimulate, rather than inhibit, the kinetics of substrate oxidation.

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  • Article: Resveratrol inhibited hydroquinone-induced cytotoxicity in mouse primary hepatocytes.
    Da-Hong Wang, Yoshie Ootsuki, Hirofumi Fujita, Masahiro Miyazaki, Qinxia Yie, Ken Tsutsui, Kuniaki Sano, Noriyoshi Masuoka, Keiki Ogino
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    ABSTRACT: Hydroquinone (1,4-benzenediol) has been widely used in clinical situations and the cosmetic industry because of its depigmenting effects. Most skin-lightening hydroquinone creams contain 4%-5% hydroquinone. We have investigated the role of resveratrol in prevention of hydroquinone induced cytotoxicity in mouse primary hepatocytes. We found that 400 µM hydroquinone exposure alone induced apoptosis of the cells and also resulted in a significant drop of cell viability compared with the control, and pretreatment of resveratrol to a final concentration of 0.5 mM 1 h before hydroquinone exposure did not show a significant improvement in the survival rate of the hepatocytes, however, relatively higher concentrations of resveratrol (≥1 mM) inhibited apoptosis of the mouse primary hepatocytes and increased cell viability in a dose-dependent manner, and in particular the survival rate of the hepatocytes was recovered from 28% to near 100% by 5 mM resveratrol. Interestingly, pretreatment with resveratrol for longer time (24 h), even in very low concentrations (50 µM, 100 µM), blocked the damage of hydroquinone to the cells. We also observed that resveratrol pretreatment suppressed hydroquinone-induced expression of cytochrome P450 2E1 mRNA dose-dependently. The present study suggests that resveratrol protected the cells against hydroquinone-induced toxicity through its antioxidant function and possibly suppressive effect on the expression of cytochrome P450 2E1.
    International Journal of Environmental Research and Public Health 01/2012; 9(9):3354-64. · 1.61 Impact Factor
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Keywords

hplc/ms examination
 
hydroquinone
 
primary substrate
 
products
 
redox exchange mechanism
 
Secondary addition products
 
tyrosinase action
 
vicariously oxidised
 
vitro studies