ABSTRACT
In our previous study, 8-hydroxydaidzein (8-OHDe) was demonstrated to be a potent and unique suicide substrate of mushroom tyrosinase. In this study, the compound was evaluated for in vitro cellular tyrosinase and melanogenesis inhibitory activities in mouse B16 melanoma cells and for in vivo skin-whitening activity in human volunteers. Tyrosinase activity and melanogenesis in the cell culture incubated with 10 microM of 8-OHDe were decreased to 20.1% and 51.8% of control, respectively, while no obvious cytotoxicity was observed in this concentration. In contrast, a standard tyrosinase inhibitor, kojic acid, showed 69.9% and 71.3% of control in cellular tyrosinase and melanogenesis activity, respectively, at a concentration as high as 100 microM. Hence, 8-OHDe exhibited more than an inhibitory effects on melanin production in B16 cells 10-fold stronger than kojic acid. In addition, when a cream containing 4% 8-OHDe was applied to human skin in an in vivo study, significant increases in the dL*-values were observed after three weeks. Moreover, the increase in the dL*-values after 8-week treatment with 4% 8-OHDe (from -0.57 to 1.94) is stronger than those of 2% 8-OHDe treatment (from 0.26 to 0.94) and 2% ascorbic acid-2-glucoside treatment (from 0.07 to 1.54). From the results of the study, it was concluded that 8-OHDe, the potent suicide substrate of mushroom tyrosinase, has depigmenting activities in both mouse melanoma cells and in human volunteers. Thus, the compound has significant potential for use in cosmetics as a skin-whitening ingredient.
Subject(s)
Isoflavones/pharmacology , Skin Lightening Preparations/pharmacology , Skin/drug effects , Adult , Animals , Ascorbic Acid/analogs & derivatives , Ascorbic Acid/chemistry , Ascorbic Acid/pharmacology , Cell Line, Tumor , Cell Survival/drug effects , Female , Healthy Volunteers , Humans , Isoflavones/chemistry , Melanins/metabolism , Melanoma, Experimental/metabolism , Melanoma, Experimental/pathology , Mice , Middle Aged , Monophenol Monooxygenase/antagonists & inhibitors , Monophenol Monooxygenase/metabolism , Skin Lightening Preparations/chemistryABSTRACT
It has been widely reported that metabolism, cell growth, cell density, product secretion and specific antibody productivity in mammalian cells are strongly affected by osmotic conditions. Previous studies have shown that hyperosmotic pressure suppresses cell growth while enhancing the productivity of individual cells, but the effect of these two changes does not result in an increase in final product concentration in the culture. An improved understanding of the basic cellular processes of a GS-NS0 mammalian cell culture system would assist in the design of a more efficient mammalian cell culture system and in further optimization of production processes. In this study, various properties of mammalian culture systems, such as productivity, cell viability, metabolism, ion balance and the genes regulated during the culture of the GS-NS0 system under osmotic pressure of iso- (290 mOsm/kg) and hyper- (450 mOsm/kg) osmolarity have been investigated, and we demonstrate that there is a decrease in the growth rate and an increase in specific production rate of hyperosmotic cultures as compared with iso-osmotic cultures. Furthermore, differences between iso- and hyper-osmotic cultures have been identified in calcium accumulation and metabolism of NH4+, glucose and lactate. Analysis of gene expression reveals regulation of over 600 genes that are implicated in processes known to be affected by changes in osmotic pressure, such as ion transport, accumulation of osmolytes, cell cycle distribution, proliferation, cytoskeletal organization and cell metabolism.
