• The Korean Journal of Mycology
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• v.38 no.2
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• pp.167-171
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• 2010

The present study aims to evaluate Cordyceps militaris water extract (CMWE) with a view to develop melanogenesis inhibitors. Inhibitory activities of CMWE against tyrosinase, L-DOPA(L-3,4-dihydroxyphenylalanine) oxidation, and melanin biosynthesis in B16 mouse melanoma cells were investigated. CMWE, at $5000\;{\mu}g/ml$, inhibited tyrosinase activity of 71% and DOPA oxidation of 40% as reacting with L-DOPA. Furthermore, B16 mouse melanoma cell survived over 50% from low to high dose on MTT assay, and CMWE markedly inhibited (> 50%) melanin synthesis at $5000\;{\mu}g/ml$. The inhibitory effect of CMWE on melanogenesis was attributed to enhancement of tyrosinase degradation. Key enzyme of melanin biosynthesis is tyrosinase which catalyses a beginning step from tyrosine to DOPA quinine and melanin formation step, respectively. These results indicated that CMWE may be a potential source of novel whitening agents for cosmetic or therapeutic application.

• Biomolecules & Therapeutics
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• v.31 no.4
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• pp.402-410
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• 2023

Long-term administration of levodopa (L-DOPA) to patients with Parkinson's disease (PD) commonly results in involuntary dyskinetic movements, as is known for L-DOPA-induced dyskinesia (LID). 5-Hydroxytryptophan (5-HTP) has recently been shown to alleviate LID; however, no biochemical alterations to aberrant excitatory conditions have been revealed yet. In the present study, we aimed to confirm its anti-dyskinetic effect and to discover the unknown molecular mechanisms of action of 5-HTP in LID. We made an LID-induced mouse model through chronic L-DOPA treatment to 6-hydroxydopamine-induced hemi-parkinsonian mice and then administered 5-HTP 60 mg/kg for 15 days orally to LID-induced mice. In addition, we performed behavioral tests and analyzed the histological alterations in the lesioned part of the striatum (ST). Our results showed that 5-HTP significantly suppressed all types of dyskinetic movements (axial, limb, orolingual and locomotive) and its effects were similar to those of amantadine, the only approved drug by Food and Drug Administration. Moreover, 5-HTP did not affect the efficacy of L-DOPA on PD motor manifestations. From a molecular perspective, 5-HTP treatment significantly decreased phosphorylated CREB and ΔFosB expression, commonly known as downstream factors, increased in LID conditions. Furthermore, we found that the effects of 5-HTP were not mediated by dopamine1 receptor (D1)/DARPP32/ERK signaling, but regulated by AKT/mTOR/S6K signaling, which showed different mechanisms with amantadine in the denervated ST. Taken together, 5-HTP alleviates LID by regulating the hyperactivated striatal AKT/mTOR/S6K and CREB/ΔFosB signaling.

• Biomolecules & Therapeutics
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• v.16 no.2
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• pp.106-112
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• 2008

The effects of harman and norharman on dopamine content and L-DOPA-induced cytotoxicity were investigated in PC12 cells. Harman and norharman decreased the intracellular dopamine content for 24 h. The $IC_{50}$ values of harman and norharman were 20.4 ${\mu}M$ and 95.8 ${\mu}M$, respectively. Tyrosine hydroxylase (TH) activity and TH mRNA levels were also decreased by 20 ${\mu}M$ harman and 100 ${\mu}M$ norharman. Under the same conditions, the intracellular cyclic AMP levels were decreased by harman and norharman. In addition, harman and norharman at concentrations higher than 80 ${\mu}M$ and 150 ${\mu}M$ caused cytotoxicity at 24 h in PC12 cells. Non-cytotoxic ranges of 10-30 ${\mu}M$ harman and 50-150 ${\mu}M$ norharman inhibited L-DOPA (20-50 ${\mu}M$)-induced increases of dopamine content at 24 h. Harman at 20-150 ${\mu}M$ and norharman at 100-300 ${\mu}M$ also enhanced LDOPA (20-100 ${\mu}M$)-induced cytotoxicity at 24 h. These results suggest that harman and norharman decrease dopamine content by reducing TH activity and aggravate L-DOPA-induced cytotoxicity in PC12 cells.

• YAKHAK HOEJI
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• v.50 no.2
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• pp.105-110
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• 2006

The effects of tributyltin acetate (TBTA), one of the endocrine-disrupting organotin compounds, on dopamine biosynthesis in PC12 cells were investigated. Treatment of PC12 cells with TBTA at $0.05\sim0.25{\mu}M$ significantly decreased the intracellular dopamine content in a concentration-dependent manner ($IC_{50}$ value, $0.17{\mu}M$). Under these conditions, tyrosine hydroxylase (TH) activity and TH mRNA level were also decreased by $0.1{\mu}M$ TBTA at 24 h, and recovered there-after. In addition, treatment with L-DOPA at 20 and $50 {\mu}M$ increased the intracellular dopamine content in PC12 cells and the increase in dopamine content by L-DOPA was significantly abolished by TBTA at $0.1\sim0.2{\mu}M$. These results indicate that TBTA at $0.1\sim0.2{\mu}M$ causes the decrease in the basal dopamine content and abolishes the increase in dopamine content in L-DOPA-treated cells in part by the inhibition of TH gene expression and activity.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.4 s.48
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• pp.485-489
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• 2004

Melanin pigmentation in human skin is a major defensive mechanism against ultraviolet light of the sun. Tyrosinase plays a key role in the biosynthesis of melanin. This is why many researches have been focused on regulations in controlling the epidermal melanization. We found that extract of Canavalia lineata inhibits mushroom tyrosinase activity, dopa oxidase activity, and melanin synthesis in B16F10 melanoma cells. To elucidate mRNA level reverse transcription polymerase chain reaction (RT-PCR) technique was used. It was revealed that A subfraction of $CHCI_3$ extract of Canavalia lineara reduced the tyrosinase mRNA expression of B16F10 melanoma cells by reverse transcription polymerase chain reaction (RT-PCR) technique.

• Korean Journal of Food Science and Technology
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• v.17 no.3
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• pp.232-236
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• 1985

The inhibiting properties of sodium benzoate on the dopachrome formation were investigated with crude enzyme preparations from homogenized tissues of raw potato tubers. The % inhibition of dopachrome formation was increased with increasing concentrations of sodium benzoate and decreasing concentrations of substrate, 3,4-dihydroxyphenylalanine(DOPA). The inhibiting action was gradually reduced with increasing temperature. Dopachrome formation tended to be greatly inhibited in the range of pH 3-5, while it revealed a sharp increase above pH 6. The results suggested that sodium benzoate might compete with the substrate for the enzyme.

• KSBB Journal
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• v.29 no.1
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• pp.1-8
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• 2014

Tyrosinases catalyze the hydroxylation of monophenolic compounds and the conversion of o-diphenols to oquinones. The enzymes are mainly involved in the modification of tyrosine into L-3,4-dihydroxyphenyl-alanine (L-DOPA) and DOPA/DOPAquinone-drived intermolecular cross-linking, which play the key roles of pigmentation to the cells. It is ubiquitously distributed in microorganisms, plants, and animals all around the nature world. They are classified as copper- containing dioxygen activating enzymes; two copper ions are coordinated with six histidine residues in their active sites and they are distinguished as met-, deoxy-, and oxy-form depending on their oxidative states. Natural extraction and recombinant protein approaches have been tried to obtain practical amounts of the enzymes for industrial application. Tyrosinases have been widely applied to industrial and biomedical usages such as detoxification of waste water containing phenolic compounds, L-DOPA as a drug of Parkinson's disease, biomaterials preparation based on the cross-linking ability and biosensors for the detection of phenolic compounds. Therefore, this review reports the mechanism of tyrosinase, biochemical and structural features and potential applications in industrial field.

• Korean Journal of Pharmacognosy
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• v.41 no.3
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• pp.221-226
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• 2010

The effects of sesamin on dopamine biosynthesis in PC12 cells were investigated. Sesamin at concentration ranges of 20-75 ${\mu}M$ significantly increased intracellular dopamine levels and tyrosine hydroxylase (TH) activities at 24 h: 50 ${\mu}M$ sesamin increased dopamine levels to 132% and TH activities to 128% of control levels. Sesamin (50 ${\mu}M$) induced the phosphorylation of TH, cyclic AMP-dependent protein kinase (PKA) and cyclic AMP-response element binding protein (CREB) for 0.5-24 h. Sesamin (50 ${\mu}M$) also increased the mRNA levels of TH and CREB for 3-24 h. In addition, sesamin (50 ${\mu}M$) associated with L-DOPA (50 and 100 ${\mu}M$) further increased the intracellular levels of dopamine for 24 h compared to L-DOPA alone. These results suggest that sesamin enhances dopamine biosynthesis and L-DOPA-induced increase in dopamine levels by inducing TH activity and TH gene expression, which is mediated by PKA-CREB systems in PC12 cells. Therefore, sesamin could serve as an adjuvant phytonutrient for neurodegenerative diseases.

• Journal of Life Science
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• v.28 no.7
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• pp.802-810
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• 2018

Aging is accompanied by changes in the body, such as graying hair, wrinkles, and black spots composed of lipid peroxides and proteins. Melanin is a polymer substance produced by an oxidation polymerization reaction from tyrosine, and it determines the color of hair and skin. It has been reported that melanin is synthesized by melanocyte, and its excessive production by reactive oxygen species is associated with aging. The purpose of this study was to determine the direct effects of Musa paradisiaca peel ethanolic extract (MPEE) on antioxidative activity and melanin synthesis. It was observed that the antioxidant activity of MPEE was similar to that of vitamin C, a positive control, in both DPPH radical scavenging assay and reducing power assay. In order to examine cytotoxicity prior to cell experimentation, 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed for B16F1 cells. MPEE was not cytotoxic at $32{\mu}g/ml$ or less. In addition, MPEE increased melanin synthesis in live cells in addition to tyrosinase activity and melanin synthesis in dihydroxyphenylalanine (DOPA)-oxidation assay in vitro. Moreover, MPEE increased melanin synthesis in cells aged by pretreatment with $H_2O_2$. The expression levels of tyrosinase-related protein (TRP)-1, TRP-2, and superoxide dismutase (SOD)-2 by western blot analysis were increased in the presence of MPEE. These results suggest that MPEE could promote the melanin synthesis as an antioxidative substance.

• Journal of Radiation Protection and Research
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• v.33 no.3
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• pp.87-91
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• 2008

We induced the activation of melanocytes in the epidermis of C57BL/6 mice by ultraviolet B (UVB) irradiation and observed the effect of Bu-Zhong-Yi-Qi-Tang (BZYQT) on the formation, and decrease of UVB-induced epidermal melanocytes. C57BL/6 mice were irradiated by UVB $80\;mJ/cm^2$ (0.5 mW/sec) daily for 7 days, and BZYQT was intraperitoneally or topically applied pre- or post-irradiation. For the estimation of change of epidermal melanocytes, light microscopic observation with dihydroxyphenylalanine (DOPA) stain was performed. Split epidermal sheets prepared from the ear of untreated mice exhibited 11-16 melanocytes/$mm^2$, and one week after UV irradiation, the applied areas show an increased number of strongly DOPA-positive melanocytes with stout dendrites. But intraperitoneal or topical treatment with BZYQT before each irradiation interrupted UVB-induced pigmentation and resulted in a marked reduction in the number of epidermal melanocytes as compared to radiation control skin. The number and size of DOPA-positive epidermal melanocytes were also significantly decreased in intraperitoneally injected or topically applicated group after irradiation with BZYQT at 3rd and 6th weeks after irradiation. The present study suggests the BZYQT as inhibitor of UVB-induced pigmentation and depigmenting agent.