• Molecules and Cells
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• v.46 no.6
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• pp.337-344
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• 2023

N-glycosylation, a common post-translational modification, is widely acknowledged to have a significant effect on protein stability and folding. N-glycosylation is a complex process that occurs in the endoplasmic reticulum (ER) and requires the participation of multiple enzymes. GlcNAc-1-P-transferase (GPT) is essential for initiating N-glycosylation in the ER. Tunicamycin is a natural product that inhibits N-glycosylation and produces ER stress, and thus it is utilized in research. The molecular mechanism by which GPT triggers N-glycosylation is discussed in this review based on the GPT structure. Based on the structure of the GPT-tunicamycin complex, we also discuss how tunicamycin reduces GPT activity, which prevents N-glycosylation. This review will be highly useful for understanding the role of GPT in the N-glycosylation of proteins, as well as presents a potential for considering tunicamycin as an antibiotic treatment.

• Molecules and Cells
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• v.25 no.4
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• pp.494-503
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• 2008

Many therapeutic glycoproteins have been successfully generated in plants. Plants have advantages regarding practical and economic concerns, and safety of protein production over other existing systems. However, plants are not ideal expression systems for the production of biopharmaceutical proteins, due to the fact that they are incapable of the authentic human N-glycosylation process. The majority of therapeutic proteins are glycoproteins which harbor N-glycans, which are often essential for their stability, folding, and biological activity. Thus, several glyco-engineering strategies have emerged for the tailor-making of N-glycosylation in plants, including glycoprotein subcellular targeting, the inhibition of plant specific glycosyltranferases, or the addition of human specific glycosyltransferases. This article focuses on plant N-glycosylation structure, glycosylation variation in plant cell, plant expression system of glycoproteins, and impact of glycosylation on immunological function. Furthermore, plant glyco-engineering techniques currently being developed to overcome the limitations of plant expression systems in the production of therapeutic glycoproteins will be discussed in this review.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.1
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• pp.29-32
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• 2004

Inhibition of the early N-glycosylation process in the endoplasmic reticulum prevents the activation of tyrosinase, a key enzyme for melanin biosynthesis. This work aims at evaluating the increased activity of N-glycosylation inhibitors in vitro b, employing a nano-sized pH-sensitive liposome as a delivery carrier. Melexsome, a pH-sensitive nano carrier loaded with glycosylation inhibitos, was prepared by the hydration method with phospholipids and cholresterol-based amphiphiles. Inhibitory effects of Melexsome on the N-glycosylation process were evaluated by EndoH ＆ PNGaseF digestion and the western blotting. Melanin synthesis was also monitored after treatment with Melexsome Interestingly, Melexsome effectively increased the efficacy of N-glycosylation inhibitors. Melexsome was also much more efficiently translocated into the cytoplasm as observed in CLSM. These results demonstrated that the amphiphilic lipid-based pH-sensitive nano-carriers could be, used as an efficient delivery system for N-glycosylation inhibitor to enhance the effects of skin whitening cosmetics.

• Journal of Microbiology
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• v.45 no.5
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• pp.431-440
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• 2007

A silkworm (Bombyx mori L.) extract known to contain naturally occurring iminosugars, including 1-deoxynojirimycin (1-DNJ) derived from the mulberry tree (Morus alba L.), was evaluated in surrogate HCV and HBV in vitro assays. Antiviral activity of the silkworm extract and one of its purified constituents, 1-DNJ, was demonstrated against bovine viral diarrhea virus (BVDV) and GB virus-B (GBV-B), both members of the Flaviviridae family, and against woodchuck hepatitis virus (WHV) and hepatitis B virus (HBV), both members of the Hepadnaviridae family of viruses. The silkworm extract exhibited a 1,300 fold greater antiviral effect against BVDV in comparison to purified 1-DNJ. Glycoprotein processing of BVDV envelope proteins was disrupted upon treatment with the naturally derived components. The glycosylation of the WHV envelope proteins was affected largely by treatment with the silkworm extract than with purified 1-DNJ as well. The mechanism of action for this therapy may lie in the generation of defective particles that are unable to initiate the next cycle of infection as demonstrated by inhibition of GBV-B in vitro. We postulate that the five constituent iminosugars present in the silkworm extract contribute, in a synergistic manner, toward the antiviral effects observed for the inhibition of intact maturation of hepatitis viral particles and may complement conventional therapies. These results indicate that pre-clinical testing of the natural silkworm extract with regards to the efficacy of treatment against viral hepatitis infections can be evaluated in the respective animal models, in preparation for clinical trials in humans.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.35 no.1
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• pp.73-78
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• 2009

In order to investigate the potential of a Dayflower (Commelina communis L.) extract as an active in gredient for whitening cosmetics, we prepared aqueous Commelina communis L. extract We measured its mushroom tyrosinase inhibitory activity, cellular tyrosinase activity, and melanin synthesis inhibitory activity in B16 melanoma cells. It did not show inhibitory activity against mushroom tyrosinase but showed melanin synthesis inhibitory activity. In a melanin synthesis inhibition assay using mouse B16-F10 melanoma cell, it suppressed melanin production up to 32% at a concentration of $1,000{\mu}/mL$ without cytotoxicity, and also reduced cellular tyrosinase activity to above 50 % above the concentration of $250{\mu}g/mL$. In study on the melanogenic protein expressions, it had especially influence on expression of tyrosinase protein, which is a well-known key protein on melanogenesis, and tyrosinase expression was gradually decreased in a dose-dependent. Dayflower also blocked N-glycosylation of TRP-2, but affected on the expression of TRP-1 rather than on blocking of N-glycosylation processing. Therefore, this result suggests that aqueous Commelina communis L. extract could be used as an active ingredient for whitening cosmetics.

• Journal of Microbiology
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• v.45 no.6
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• pp.578-582
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• 2007

The primary objective of this study was to assess the in vitro melanogenesis inhibitory effects of methanolic extracts of the edible and medicinal lichens, Umbilicaria (Gyrophora) esculenta and Usnea longissima. The quantities of the total phenolic compounds of methanolic extract of the two lichen extracts were determined to be 1.46% and 2.62%, respectively. In order to evaluate the antioxidative effects of the extracts, we also measured electron donating abilities (EDA) and lipid peroxidation rates. The EDA values measured by the reduction of 1.1'-diphenyl-2-picrylhydrazyl (DPPH) were 72.8% and 80.7% for the extracts, with $SC_{50}$ (median scavenging concentration) values of $1.29{\pm}0.05\;mg/ml$ and $1.03{\pm}0.06\;mg/ml$, respectively. The rates of inhibition of lipid peroxidation using linoleic acid were 92.1% and 97.3% for the extracts, with $IC_{50}$ (median inhibitory concentration) values of $0.57{\pm}0.05\;mg/ml$ and $0.53{\pm}0.06\;mg/ml$, respectively. The inhibitory rates of the extracts against tyrosinase were 67.4% and 84.8%, respectively. The extracts were shown to reduce melanin formation in human melanoma cells. Melanin contents in the samples treated with 0.01% and 0.1% U. esculenta were 47.1% and 31.2%, respectively, and those treated with 0.01% and 0.1% Usnea longissima were 51.1% and 34.9%, respectively, whereas a value of 54.0% was registered when ascorbic acid was utilized as a positive control. In addition to direct tyrosinase inhibition, it was determined that the lichen extracts affected the activity of tyrosinase via the inhibition of tyrosinase glycosylation. As a result, the methanolic extracts of U. esculenta and Usnea longissima evidenced melanogenesis inhibitory effects, which occurred via multiple routes.

• Korean Journal of Plant Resources
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• v.26 no.5
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• pp.526-532
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• 2013

In this study, we investigated the effect of 88 marine algae extracts on melanin synthesis to develop new whitening agents. Among varieties of marine algae tested, the ethyl acetate extracts from Endarachne binghamiae (EB), Scytosiphon lomentaria, Sargassum yezoense, Ecklonia cava and Sargassum fusiforme inhibited melanin synthesis in melan-a cells. EB treatment showed the strongest inhibitory activity in melanin synthesis, compared with that of other extracts. EB-mediated inhibition of melanin synthesis appeared to be associated with inhibition of ${\alpha}$-glucosidase-dependent glycosylation of tyrosinase in melan-a cells. In addition, EB treatment did not affect mushroom tyrosinase or cell-extracted tyrosinase activity in vitro. Taken together, our findings suggest that anti-browning effect of EB on skin is mediated through regulation of ${\alpha}$-glucosidase activity and subsequent inhibition of tyrosinase activity and melanin synthesis, and further development of EB as a potential agent for skin whitening.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.651-652
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• 2003

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.649-650
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• 2003

• KSBB Journal
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• v.28 no.2
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• pp.137-145
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• 2013

In order to develop new skin whitening agents, we prepared the $CH_2Cl_2$ layer (NGC) and BuOH layer (NGB) of 75% EtOH extract of the Nelumbinis nucifera Gaertner. We measured their tyrosinase inhibitory activity in vitro and melanin synthesis inhibitory activity in B16-F1 melanoma cells. They did not show inhibitory activity against mushroom tyrosinase but showed melanin synthesis inhibitory activity in a dose-dependent manner. In a melanin synthesis inhibition assay, NGC and NGB suppressed melanin production up to 52% and 46% at a concentration of $100{\mu}g/mL$, respectively. To elucidate the mechanism of the inhibitory effects of NGC and NGB on melanogenesis, we measured the expression of melanogenesis-related proteins by western blot assay. As a result, NGC suppressed the expression of tyrosinase, tyrosinase related protein 1 (TRP-1), tyrosinase related protein 2 (TRP-2), phosphorylated cAMP responsive element binding (p-CREB) protein, and microphthalmia associated transcription factor (MITF). And NGB inhibited the protein expression of tyrosinase and MITF, but had no significant effect on TRP-1, TRP-2, and p-CREB expression. Moreover, NGB increased the expression of phosphorylated extracellular signal-regulated kinase (p-ERK). In addition, we examined the inhibitory effect on the glycosylation of tyrosinase. As a result, NGC and NGB inhibited the activity of ${\alpha}$-glucosidase in vitro and the glycosylation of tyrosinase in B16-F1 melanoma cells. From these results, we concluded that NGC and NGB could be used as active ingredients for skin whitening.