• Korean Journal of Crystallography
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• v.15 no.2
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• pp.88-92
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• 2004

An organometallic compound, $(C_{16}H_{21}B_{10}BrOSn)$, was synthesized from o-carborane, closo-1-[(methoxyl)methyl]-o-carborane $(HCab^o)$, and $SnMe_2Br_2$. The molecular structure of this complex has been determined by X-ray diffraction. Crystallographic data: orthorhombic, space group Pna2, a = 17.9292(15)$\AA$, b= 7.2066(4)$\AA$, c=13.0582(10)$\AA$, Z=4, V=1687.2(2) $\AA^3$. The structure was solved by direct methods and refined by full-matrix least-squares methods to give a model with a reliability factor R=0.0574 for 1724 reflections.

• The Journal of Korean Medicine
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• v.26 no.1 s.61
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• pp.1-10
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• 2005

Objective: We examined the antimetastatic effect of Curcuma zedoaria Roscoe (CZ) on pulmonary metastasis of B 16 cells. Methods: For 6 weeks, Zedoariae Rhizoma made from dried CZ were dissolved in distilled water and administered to mice 2 weeks before they were injected with B]6 melanoma cells. Mice were given CZ at doses of 250 and 500 mg/kg, and were compared for lung weight, survival days, and NO production. Results: Intake of CZ throughout the experiment extended the average survival time. Intake after B16 cell injection slightly prolonged survival time, but intake before B]6 cell injection did not influence life span. We examined the effect of CZ on macrophage function by measuring NO production. After the macrophages were given CZ for 6 weeks, the amount of NO generated by the macrophages stimulated with LPS in culture medium increased. NO generated by the macrophages also served as a cytotoxic factor against B16 melanoma cells. B16 melanoma-conditioned medium reduced NO production by macrophages. However, CZ treatment reversed the reduction in NO production by the conditioned medium significantly. Conclusion : These findings may suggest that macrophage function-modulating activity by CZ appears to underlie its antimetastatic activity, which leads to a decrease in the number of lung metastatic surface nodules and the extension of life span.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.3
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• pp.227-247
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• 2015

An X-band $8{\times}16$ dual-polarized active phased array antenna system has been implemented based on the substrate integrated waveguide(SIW) technology having low propagation loss, complete EM shielding, and high power handling characteristics. Compared with the microstrip case, 1 dB less is the measured insertion loss(0.65 dB) of the 16-way SIW power distribution network and doubled(3 dB improved) is the measured radiation efficiency(73 %) of the SIW sub-array($1{\times}16$) antenna element. These significant improvements of the power division loss and the radiation efficiency using the SIW, save more than 30 % of the total power consumption, in the active phased array antenna systems, through substantial reduction of the maximum output power(P1 dB) of the high power amplifiers. Using the X-band $8{\times}16$ dual-polarized active phased array antenna system fabricated by the SIW technology, the main radiation beam has been steered by 0, 5, 9, and 18 degrees in the accuracy of 2 degree maximum deviation by simply generating the theoretical control vectors. Performing thermal cycle and vacuum tests, we have found that the SIW array antenna system be eligible for the space environment qualification. We expect that the high efficiency SIW array antenna system be very effective for high performance radar systems, massive MIMO for 5G mobile systems, and various millimeter-wave systems(60 GHz WPAN, 77 GHz automotive radars, high speed digital transmission systems).

• Journal of Life Science
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• v.19 no.1
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• pp.75-80
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• 2009

Melanogenesis is a physiological process that results in the synthesis of melanin pigments. Tyrosinase is a key enzyme for melanin biosynthesis, and hyperpigmentation disorders are associated with abnormal accumulation of melanin pigments, which can be improved by treatment with depigmenting agents. Among the possible melanin-reducing compounds, tyrosinase inhibitors are most promising for preventing and treating pigmentation disorder and are used as skin-whitening agents in the cosmetic industry. In the present study, the effects of fucoidan on melanogenesis and tyrosinase activity of B16F10 melanoma cells were investigated. Melanin synthesis and tyrosinase activity in B16F10 melanoma cells were decreased in a dose-dependent manner by fucoidan. Melanin production and tyrosinase activity in B16F10 melanoma cells stimulated by a-melanocyte stimulating hormone (a-MSH) were inhibited by fucoidan with a dose-dependent manner compared to control. Fucoidan inhibited tyrosinase activity of B16F10 melanoma cells with a dose-dependent manner as assessed by 3,4-dihydroxyphenylalanine (DOPA) staining. In conclusion, these findings indicate that fucoidan, which inhibit melanin synthesis and tyrosinase activity, is an effective skin-whitening agent.

• Journal of the Korean Chemical Society
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• v.44 no.6
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• pp.533-540
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• 2000

Melanization of B16 melanoma cells was comparatively studied by the aqueous extract of Epimedium koreanum Nakai(EK) and $\alpha$-MSH. In addition, inhibitory effects of RA was investigated. B16 melanoma cells(about 1${\times}10_5$) have been shown an increase in tyrosinase activity and melanin contents in proportion to concentration of $\alpha$-MSH when treated with $\alpha$-MSH and incubated for 72 hrs. They indicated a 350% increase in tyrosinase activity and a 290% increase in melanin contents at 8 ng/mL. In case of EK, they have been shown a 200% increase in tyrosinase activity and a 180% increase in melanin contents at 100 ${\mu}g$/mL. In addition of RA to the above condition, they have been shown an inhibition from 350% to 210% in tyrosinase activity and from 290% to 250% in melanin contents in $\alpha$-MSH, and inhibition from 200% to 100% in tyrosinase activity and from 180% to 120% in melanin contents in EK. From the above results, it is suggested that EK promotes melanization of B16 melanoma cells through cAMP pathway, whereas RA inhibits it.

• 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 Life Science
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• v.21 no.2
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• pp.251-256
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• 2011

EGCG, catechins in green tea, is a kind of phytochemical. Through the regulation of signal pathways, EGCG has been known to show anti-oxidant and anti-tumor effects in cells. In this study, we investigated the apoptotic effects of EGCG through AMP-activated protein kinase (AMPK) signal pathways, including hypoxia inducible factor-1 alpha (HIF-$1{\alpha}$). The experiments were performed in B16F10 melanoma cells in a hypoxic state. AMPK is activated by ATP consumption such as nutrient deficiency, exercise, heat shock, etc. The activated AMPK that plays an important role as an energy sensor inhibits proliferation of cancer cells, as well as inducing apoptosis. HIF-$1{\alpha}$, the primary transcriptional regulator of the response to oxygen deprivation, plays a critical role in modulating tumor growth and angiogenesis in a hypoxic state. The apoptotic effects of EGCG were studied in B16F10 cells in a hypoxic state. The results show that EGCG inhibits the transcriptional activity of HIF-$1{\alpha}$ and induces apoptosis. These observations suggest that EGCG may exert inhibitory effects of angiogenesis and control tumor cell growth in hypoxic melanoma cells.

• Journal of Life Science
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• v.29 no.11
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• pp.1200-1207
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• 2019

Ultraviolet radiation exposure is a major cause of extrinsic skin aging, which leads to skin hyperpigmentation. Loganin, a major iridoid glycoside obtained from Corni fructus, has anti-inflammatory, anti-diabetic, and neuroprotective effects. In this study, we investigated the mechanisms underlying the anti-melanogenic effects of loganin in B16F10 melanocytes treated with ${\alpha}$-melanocyte stimulating hormone (${\alpha}-MSH$) and 3-isobutyl-1-methylxanthine (IBMX). Anti-melanogenic activity was measured by treating cells with loganin at concentrations between 1 and $20{\mu}m$. Cell viability assays confirmed that doses of loganin up to $20{\mu}m$ were not cytotoxic. Loganin significantly and dose-dependently decreased intracellular melanin production. We also investigated potential molecular signaling pathways for the anti-melanogenesis effects of loganin. Western blotting showed that treatment with ${\alpha}-MSH$ and IBMX increased the phosphorylation of cAMP response element-binding protein (CREB) and the gene expressions of microphthalmia-associated transcription factor (MITF) and tyrosinase. Addition of loganin suppressed these increases, while promoting the phosphorylation of extracellular signal regulated kinase (ERK) and the anti-melanogenesis response. Our data therefore indicated that loganin could attenuate the increased melanin synthesis induced by ${\alpha}-MSH$ and IBMX treatment of B16F10 melanocytes. This attenuation appears to occur by downregulation of CREB phosphorylation and MITF and tyrosinase gene expression and upregulation of ERK phosphorylation. These finding suggests that loganin could be a valuable candidate for treatment of skin diseases related to hyperpigmentation.

• 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.

• Journal of Life Science
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• v.34 no.2
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• pp.105-112
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• 2024

In this study, the various whitening activities of Inonotus obliquus were assessed for potential use as functional cosmetic materials. When measuring electron donating ability to confirm the antioxidant ability of I. obliquus extract, increased activity was observed as the concentration increased, and it was found an outstanding antioxidant capacity of 82.1% at a 1,000 ㎍/ml concentration. Also, the tyrosinase inhibitory effect, related to a whitening effect, was found to have inhibitory activity that increased in a concentration-dependent manner. The results of verifying the viability of melanoma cells (B16F10) using an MTT assay showed cell viability of more than 80% at concentrations below 100 ㎍/ml. Therefore, cell-related experiments were conducted at 25, 50, and 100 ㎍/ml concentrations. By measuring protein expression related to melanin synthesis via treating B16F10 cells with I. obliquus extract, it was confirmed that protein expression was inhibited in all factors, depending on the concentration. TRP-1 and MITF appeared by 40.1% and 64.2% amount of expression, respectively, at 100 ㎍/ml concentrations, and tyrosinase and TRP-2 were verified as having better protein expression inhibition than arbutin. In measuring mRNA expression related to melanin synthesis by treating B16F10 cells with I. obliquus extract, it was confirmed that mRNA expression was suppressed as the concentration increased. Accordingly, it was confirmed that I. obliquus extract has excellent whitening activity and could be used as a cosmetic material.