• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.454-460
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• 2000

It is difficult to accurately evaluate the effect of lipophilic compounds in aqueous reaction system of enzymes because they are immiscible with water. To screen lipophilic inhibitors of tyrosinase which catalyzes the synthesis of melanin in vivo, an optically clear organic system composed of organic solvent, surfactant, and water, often called reverse micelles(RM), was introduced. Optimal RM to let tyrosinase act normally was composed of isooctane as an organic solvent and dioctyl sulfosuccinate(AOT) of 100 mM as a surfactant. When a molar ratio of water to surfactant was 15, tyrosinase(105.3 units) in RM showed a similar reactivity toward 3,4-dihydroxyphenylalanine(0.18 mM) as in the aqueous assay system. In the presence of cinnamic acid, the product formation of tyrosinase reaction was proportional to the reaction time. This indicates that the inhibitory effect of lipophilic compounds could be analyzed in RM.

• Journal of Life Science
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• v.27 no.2
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• pp.139-148
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• 2017

The inhibition of tyrosinase, a key enzyme in mammalian melanin synthesis, plays an important role in preventing skin pigmentation and melanoma. Therefore, tyrosinase inhibitors are very important in the fields of medicine and cosmetics. However, only a few tyrosinase inhibitors are currently available because of their toxic effects on skin or lack of selectivity and stability. Therefore, we synthesized a novel series of (E)-2-(substituted benzylidene)-2,3-dihydro-1H-cyclopenta[a]naphthalen-1-one derivatives and evaluated their inhibitory effects on mushroom tyrosinase, with the aim of discovering a novel tyrosinase inhibitor. Among 19 derivatives, MHY3655 ($IC_{50}=0.1456{\mu}M$) showed the strongest inhibitory effect on tyrosinase activity compared to kojic acid ($IC_{50}=17.2{\mu}M$), a well-known tyrosinase inhibitor. In addition, MHY3655 showed competitive inhibition on Lineweaver-Burk plots. We confirmed that MHY3655 strongly interacts with mushroom tyrosinase residues through the docking simulation. Substitutions with a hydroxy group at both R2 and R4 in the phenyl ring indicated that these groups play a major role in the high binding affinity to tyrosinase. Further, MHY3655 did not show cytotoxicity at the concentrations tested in B16F10 melanoma cells. In conclusion, the novel compound MHY3655 potentially shows tyrosinase inhibitory activity, and it could be used as an ingredient in whitening cosmetics.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.35 no.3
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• pp.203-208
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• 2009

Doenjang (Korean fermented soybean paste) is a unique fermented food in Korea. It has been traditionally manufactured from soybeans, by Jang Yang process. We focused on the newly formed compound in highly aged Doenjang and its biological activity. One new o-dihydroxyisoflavone, 7,3',4'-trihydroxyisoflavone and two known o-dihydroxyisoflavone derivatives were isolated from 5-year-old Doenjang and evaluated as potent antioxidant and whitening effect by comparing with other known isoflavone. 7,8,4'-Trihydroxyisoflavone (compound 1), 7,3',4'-trihydroxyisoflavone (compound 2) and 6,7,4'-trihydroxyisoflavone (compound 3) inhibited DPPH (diphenyl-1-picrylhydrazyl) formation by 50 % at a concentration of $21.5{\pm}0.2$, $28.7{\pm}0.4$ and $32.6{\pm}0.6$ ($IC_{50}$) respectively, whereas daidzein showed weak DPPH radical scavenging activity. In superoxide scavenging effect were measured in one assay. Compound 1 ($IC_{50}=18.10{\pm}0.2{\mu}M$) and 2 ($IC_{50}=10.54{\pm}0.4{\mu}M$) show significant inhibitory activity and greater effect than L-ascorbic acid. But compound 3 and daidzein showed lower inhibition activity. Also, o-dihydroxyisoflavone derivatives evaluated as potent inhibitors on tyrosinase activity and melanin formation in melan-a cells. Compound 1 ($IC_{50}=11.21{\pm}0.2{\mu}M$), compound 2 ($IC_{50}=5.23{\pm}0.6{\mu}M$) exhibited significant inhibitory effect on tyrosinase activity. Furthermore, those compounds are significantly suppressed the cellular melanin formation by 50 % at a concentration of $12.23{\pm}0.7{\mu}M$ (1) and $7.83{\pm}0.7{\mu}M$ (2). This result suggests that 7,3',4'-trihydroxyisoflavone from highly aged Doenjang could be used as an active ingredient for cosmetics.

• KSBB Journal
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• v.19 no.2
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• pp.118-124
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• 2004

Melanocytes synthesize melanin within discrete organelle termed melanosomes which are transferred to the surrounding keratinocytes and can be produced in varying sizes, numbers and densities. Skin whitening products have become increasingly popular in the past few years. The most successful natural skin whitening agents are: Arbutin, Vitamin C, Kojic acid, Mulberry, which are all tyrosinase inhibitors. In this work, melanoston, a melanogenesis inhibitor isolated from yeast was studied to understand its mechanism of melanogenesis inhibition. It was found that melanoston was not a tyrosinase inhibitor, while when melanoston was applied to the B16 melanoma cell culture media, the intracellular tyrosinase activity was decreased by more than 30％, When B16 melanoma was stimulated with ${\alpha}$-MSH, cell morphololgy was dramatically changed to have lots of dendrites on the cell membrane surface. On the other hand, B16 was treated with ${\alpha}$-MSH and melanoston, simultaneously, the change of cell morphology was not so great. This inhibition effect of melanoston was found to be related to the inhibition of intracellular activation and transportation of tyrosinase, which was observed by immunostaining of B16 melanoma using anti-tyrosinase antibody. From these results, melanoston was regarded as an inhibitor to the differentiation of melanoma cells.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.31 no.1 s.49
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• pp.25-33
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• 2005

Melanocytes synthesize melanin within discrete organelle termed melanosomes which are transferred to the surrounding keratinocytes and can be produced in varying sizes, numbers and densities. Skin whitening products have become increasingly popular in the past few years. The most successful natural skin whitening agents are: arbutin, vitamin C, kojic acid, and mulberry, which are all tyrosinase inhibitors. In this work, melanoston, a melanogenesis inhibitor isolated from yeast was studied to understand its mechanism of melanogenesis inhibition. It was found that melanoston was not a tyrosinase inhibitor, while when melanoston was applied to the B16 melanoma cell culture media, the intracellular tyrosinase activity was decreased by more than $30\%$. When B16 melanoma was stimulated with $\alpha$-MSH, cell morphololgy was dramatically changed to have lots of dendrites on the cell membrane surface. On the other hand, B16 was treated with $\alpha$-MSH and melanoston, simultaneously, the change of cell morphologv was not so great. This inhibitory effect of melanoston was found to be related to the inhibition of intracellar activation and transportation of tyrosinase, which was observed by irmmunostaining of B16 melanoma using anti-tyrosinase antibody. From these results, melanoston was regarded as an inhibitor to the differentiation of melanoma cells.