H2O2 accumulation by catalase reduction changes MAP kinase signaling in aged human skin in vivo.
ABSTRACT To understand the molecular alterations occurring during the aging process, we compared mitogen-activated protein (MAP) kinase activities in the intrinsically aged and photoaged skins in the same individuals. Furthermore, we investigated the molecular events related to MAP kinase changes in intrinsically aged and photoaged skins. We found that extracellular-signal-regulated kinase (ERK) activity in photoaged skin was reduced, and that the activities of c-Jun N-terminal kinase (JNK) and p38 kinase were increased compared with intrinsically aged skin in the same individuals. Phospho-c-Jun levels and activator protein 1 activities in photoaged skin were also higher than in intrinsically aged skin. Moreover, catalase activity was found to be much reduced in primary dermal fibroblasts from photoaged skin, and as a result, H2O2 accumulated more in primary dermal fibroblasts in photoaged skin. In addition, treating primary dermal fibroblasts from photoaged skin with catalase reduced H2O2 levels, reversed aging-dependent MAP kinase changes, and inhibited matrix metalloproteinase (MMP)-1 expression. Our results indicate that the accumulation of reactive oxygen species due to catalase attenuation may be a critical aspect of the MAP kinase signaling changes that may lead to skin aging and photoaging in human skin in vivo. Thus, the induction and regulation of endogenous antioxidant enzymes including catalase may offer a strategy for preventing and treating skin aging.
Article: Effects of hydroquinone and its glucoside derivatives on melanogenesis and antioxidation: Biosafety as skin whitening agents.[show abstract] [hide abstract]
ABSTRACT: The biosafety of hydroquinone and its derivatives as skin whitening agent remains controversial. Here, we investigated the effects of hydroquinone, arbutin, and deoxyarbutin (d-arb) on melanogenesis and antioxidation using cultured melan-a melanocytes in the presence or absence of ultraviolet A (UVA)-induced oxidative stress and determined whether d-arb enables to be an alterative to hydroquinone and arbutin for skin whitening use. d-arb was synthesized in this study by removing all hydroxyl groups from the glucose side-chain of arbutin. Tyrosinase activity was measured by (14)C-tyrosine incorporation, the intracellular reactive oxygen species (ROS) level was monitored by H(2)DCFDA fluorescence labeling, and the cell viability was determined by MTT assay in murine melan-a melanocytes treated with hydroquinone, arbutin and deoxyarbutin in the presence or absence of UVA-induced oxidative stress. The cytotoxicity of hydroquinone and arbutin except for d-arb was increased while the cells exposed to a nontoxic dose (3J/cm(2)) of UVA irradiation. Suppressed ROS generation was noted by the treatment of d-arb to compare with arbutin and hydroquinone. All three compounds had a similar inhibition on tyrosinase activity in dose-dependent manners with two- to three-fold decreases over the untreated control. There was no change in expression of tyrosinase protein in cells treated with arbutin or hydroquinone, but a decreased protein expression of tyrosinase was seen in deoxyarbutin-treated cells. Deoxyarbutin exerts potent tyrosinase inhibition, lessened cytotoxicity, and certain antioxidation potential, may serve as an effective and safe alternative to hydroquinone for use in skin whitening.Journal of dermatological science 07/2009; 55(3):179-84. · 3.71 Impact Factor