• YAKHAK HOEJI
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• v.45 no.2
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• pp.214-219
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• 2001

Nineteen hydrolysable tannins isolated from the Euphorbia helioscopia (Euphorbiaceae) were tested for the inhibitory effect on mushroom tyrosinase activity in vitro. Inhibitory effect of gallotannin group exhibited more potent than that of phenolcarboxylic acid and ellagitannin groups against the enzyme activity. The inhibitory activity by pentagalloyl glucose on mushroom tyrosinase was more potent ($IC_{50}$/, 4.9 $\mu$M) than that of kojic acid ($IC_{50}$/, 8.7 $\mu$M).

• Journal of the Society of Cosmetic Scientists of Korea
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• v.23 no.3
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• pp.115-121
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• 1997

To identify inhibitors of melanogenesis, we compared the effects of 5 compounds on mushroom tyrosinase, human melanocytic tyrosinase activity and melanin content. The cytotoxicyty of the components were also tested on cultured human melanoctes. Kojic acid showed marked inhibitory effect both on mushroom and human tyrosinase activity. This action of kijic acid is stronger than that of ascorbic acid. Arbutin inhibited human tyrosinase activity of cultured melanocytes although it had slightly inhibitory effect on mushroom tyrosinase activity. Azelaic acid had no effect on human tyrosinase activity. Melanin production was inhibited significantly by kojic acid and tranexamic acid. MTT assay showed that all of the compounds were non-cytotoxic to melanocytes at the concentrations tested. These results suggest that the effect of kojic acid on cultured meanocytes involve inhibition of tyrosinase activity and melanogenesis without affection the cell number.

• Journal of Life Science
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• v.16 no.3 s.76
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• pp.396-399
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• 2006

Crude extract prepared from sweet potato possessed inhibitory activity toward mushroom tyrosinase. The inhibitory activity was dependent upon the addition amount of sweet potato extract. After heating the sweet potato extract at $95^{\circ}C$ for 20 min, its inhibitory activity retained 37.3%. Its optimum activity was shown at pH ranges of 5.0-7.0. The tyrosinase inhibitory activity was disappeared by dialysis, which suggests the inhibitory activity of sweet potato extract is caused by some compounds of low molecular weight.

• Journal of Microbiology and Biotechnology
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• v.16 no.12
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• pp.1977-1983
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• 2006

Kaempferol was isolated and identified from the methanol extract of the flowers of Impatiens balsamina. Kaempferol showed inhibitory activity against mushroom tyrosinase with an $ID_{50}$ of 0.042 mM. Inhibition kinetics, as determined using a Lineweaver-Burk plot, showed kaempferol to be a competitive inhibitor of mushroom tyrosinase with a $K_i$ value of 0.011 mM. The lag phase of tyrosine hydroxylation catalyzed by mushroom tyrosinase clearly increased on increasing the concentration of kaempferol. In addition to its tyrosinase inhibiting activity, kaempferol strongly inhibited melanin production by Streptomyces bikiniensis, in a dose-dependent manner, without inhibiting cell growth. For comparative purposes, the tyrosinase inhibitory activity of kaempferol was also assayed versus quercetin, a positive standard.

• YAKHAK HOEJI
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• v.45 no.5
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• pp.522-528
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• 2001

Tyrosinase plays an important role in the process of melanin biosynthesis, and it is a biochemical target enzyme for skin-whitening agents and the remedy for disturbances in pigmentation. We have screened 25 natural plant extracts for inhibitory effects against DOPA oxidase activity of tyrosinase. For the inhibitory effect against DOPA oxidase activity of tyrosinase, the recombinant human tyrosinase and the purified mushroom tyrosinase were used. Each of the dried plants extracted with methanol, and then the extracts were subjected to sequential fractionations with methylene chloride, ethyl acetate, n-butanol and water, respective The methylene chloride fractions of Angelica tenuissima, Nardostachys chinensis, Bombyx mop and Saposhnikovia divaricata, and the n-butanol fraction of Bombyx mori notably inhibited the human tyrosinase activity as well as mushroom tyrosinase activity (more than 90% inhibition). This study suggests that the above extracts have a potential as whitening agents as single ingredients or in combination with other of the extracts.

• Korean Journal of Pharmacognosy
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• v.35 no.4 s.139
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• pp.380-383
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• 2004

The purpose of this study was to evaluate mushroom Tyrosinase inhibitory activity of Cuscuta japonica Choisy and C. australis R.Be. The experimental materials were expressed juice from their stems and flowers, both water and ethanol extracts, their seeds, and two kinds of commercially available cosmetic packing Wontosa and Bupjetosa (made from seeds of C. japonica). The 50% inhibitory concentration $(IC_{50})$ of C. Japonica juice was 5.4 mg/ml. However, C. australis juice showed negligible mushroom tyrosinase inhibitory activity. The $IC_{50}$ of water extracted C. japonica seed was $54.0\;{\mu}g/ml$, water extracted product of Wontosa $50.0\;{\mu}g/ml$ and Bupjetosa $40\;{\mu}g/ml$. The $IC_{50}$ of ethanol extracted C. japonica seed was $10\;{\mu}g/ml$, Wontosa $10\;{\mu}g/ml$ and Bupjetosa $20\;{\mu}g/ml$.

• Korean Journal of Korean Medical Institute of Dermatology and Aesthetics
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• v.1 no.1
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• pp.91-97
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• 2005

(1) Objectives: To discover natural skin-lightening agents, we have evaluated the inhibitory activity of EtOH extracts from 20 medicinal plants against mushroom tyrosinase. (2) Methods: Tyrosinase activity was determined by the dopachrome method using L-tyrosine as the substrates. (3) Results: Of the plant extracts tested, the extracts of 4 plants, Albizzia julibrissin, Curcuma longa, Anethum graveolens and Sophora flavescens, exhibited potent inhibitory activity (> 50%) in mushroom tyrosinase assay. Four plant extract, extracts of Agrimonia pilosa, Paeonia moutan, Magnolia obovata and Eugenia caryophyllata also showed relatively strong inhibitory (> 40%) against mushroom tyrosinase. (4) Conclusion: These active medicinal plants may be useful for the development of skin-whitening agents. Since the active medicinal plants may contain effective tyrosinase inhibitors even more than kojic acid, further study to identify the active constituents from the plants is expected.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.3
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• pp.320-326
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• 2017

This study investigated the water extracts of fallen pear (FPWE) on tyrosinase activity and melanogenesis. In the present study, we examined the effects of FPWE on mushroom tyrosinase activity in vitro, B16F10 melanoma cell tyrosinase activity, melanin contents, and expression of melanogenic enzyme proteins such as tyrosinase. An apparent down-regulatory effect on tyrosinase activity was observed when B16F10 cells were incubated with FPWE. Results of melanin assay using B16F10 cells treated with different concentrations (50, 125, and $250{\mu}g/mL$) of FPWE showed a dose-dependent decrease in melanin content. To determine whether or not FPWE indirectly affects tyrosinase activity, we assessed mushroom tyrosinase activity upon treatment with various concentrations (125, 250, 500, and $1,000{\mu}g/mL$) of FPWE. In addition, we investigated changes in the protein level of tyrosinase by using Western blotting. Tyrosinase and microphthalmia-associated transcription factor expression levels in B16F10 melanoma cells were reduced in a dose-dependent manner by FPWE. These results suggest that FPWE reduced melanin formation by inhibition of tyrosinase activity. Therefore, we suggest that FPWE could be used an effective whitening agent for skin.

• Journal of Pharmaceutical Investigation
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• v.36 no.2
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• pp.103-107
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• 2006

In order to develop hydroquinone analogues for topical delivery, a structure-activity relationship study has been performed. A series of 2-substituted hydroquinones were tested for their ability to inhibit mushroom tyrosinase, alter melanin release and exert cytotoxicity in B6-F10 melanocytes. The electronic property of the 2-substituents did not affect the tyrosinase inhibition nor melanocyte toxicity. However, lipophilicity did affect to some degree the tyrosinase inhibition. The discrepancy in the structure-activity relationship may be due to the poor aqueous solubility of select analogues. Compounds with steric bulk at the 2-position seems to be less soluble, not enabling the analogue to interact effectively with the tyrosinase enzyme. Among the analogues tested, 2-isopropyl hydroquinone seems to be the most promising candidate for topical delivery, being the least toxic analogue with moderate melanin release inhibition.

• Preventive Nutrition and Food Science
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• v.6 no.1
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• pp.16-18
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• 2001

The inhibitory effect of onion extract on mushroon tyrosinase activity was investigated. The enzyme activity was inhibited by 96.3% with th addition of onion extract. The inhibitor action of onion extract toward mushroom tyrosinase activity slightly increased after heat treatment at 10$0^{\circ}C$ for 10 mn (97.5%) and decreased after incubation of the extract at pH 2.3 for 3hrs (79.9%). However, the inhibitor action of the extract after dialysis decreased to18.8%. The onion extract showed drastic inhibition of the browning in mushroom.