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Skin Protective Effect of Epigallocatechin Gallate
Kim, Eunji,Hwang, Kyeonghwan,Lee, Jongsung,Han, Sang Yun,Kim, Eun-Mi,Park, Junseong,Cho, Jae Youl MDPI 2018 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.19 No.1
<P>Epigallocatechin gallate (EGCG) is a catechin and an abundant polyphenol in green tea. Although several papers have evaluated EGCG as a cosmetic constituent, the skin hydration effect of EGCG is poorly understood. We aimed to investigate the mechanism by which EGCG promotes skin hydration by measuring <I>hyaluronic acid synthase</I> (<I>HAS</I>) and <I>hyaluronidase</I> (<I>HYAL</I>) gene expression and antioxidant and anti-pigmentation properties using cell proliferation assay, Western blotting analysis, luciferase assay, 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, and reverse transcription polymerase chain reaction (RT-PCR) analysis. RT-PCR showed that EGCG increased the expression of natural moisturizing factor-related genes <I>filaggrin</I> (<I>FLG</I>), <I>transglutaminase-1</I>, <I>HAS-1</I>, and <I>HAS-2</I>. Under UVB irradiation conditions, the expression level of <I>HYAL</I> was decreased in HaCaT cells. Furthermore, we confirmed the antioxidant activity of EGCG and also showed a preventive effect against radical-evoked apoptosis by downregulation of caspase-8 and -3 in HaCaT cells. EGCG reduced melanin secretion and production in melanoma cells. Together, these results suggest that EGCG might be used as a cosmetic ingredient with positive effects on skin hydration, moisture retention, and wrinkle formation, in addition to radical scavenging activity and reduction of melanin generation.</P>
김보현(Bohyeon Kim),황경환(Kyeonghwan Hwang),허장욱(Jangwook Hur) 한국신뢰성학회 2016 신뢰성응용연구 Vol.16 No.3
Purpose: ASRP for the domestic development guided missiles requires not only for the reliability evaluation of the products in storage but also for the life cycle management of the products including development prototypes and initial production items. Methods: For this purpose, it should be performed to build a performance database before and after the accelerated aging test with shelf life items including development prototypes and initial production items, based on which the lifetime prediction should also be carried out. In addition, HILS must be applied for the acceptance test with the initial and follow-up production items, and also for ASRP for the long-term storage products in order to secure systematic quality assurance. Results: The results for the life cycle reliability Improving of domestic development of guided missiles are DB building of prescription Item performance, active application of HILS, Management associated with guided missiles life cycle and to Secure technology data about the introduction of foreign guided missiles. Conclusion: Furthermore, it is demanded that DTaQ, the managing agency of ASRP, actively take part in the process to maintain reliability engagement consistency over the life cycle of guided missiles.
Antioxidant and Cytoprotective Effects of (−)-Epigallocatechin-3-(3″-O-methyl) Gallate
Kim, Eunji,Han, Sang Yun,Hwang, Kyeonghwan,Kim, Donghyun,Kim, Eun-Mi,Hossain, Mohammad Amjad,Kim, Jong-Hoon,Cho, Jae Youl MDPI AG 2019 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.20 No.16
<P>Reactive oxygen species (ROS) are generated from diverse cellular processes or external sources such as chemicals, pollutants, or ultraviolet (UV) irradiation. Accumulation of radicals causes cell damage that can result in degenerative diseases. Antioxidants remove radicals by eliminating unpaired electrons from other molecules. In skin health, antioxidants are essential to protect cells from the environment and prevent skin aging. (−)-Epigallocatechin-3-(3″-O-methyl) gallate (3″Me-EGCG) has been found in limited oolong teas or green teas with distinctive methylated form, but its precise activities have not been fully elucidated. In this study, we examined the antioxidant roles of 3″Me-EGCG in keratinocytes (HaCaT cells). 3″Me-EGCG showed scavenging effects in cell and cell-free systems. Under H2O2 exposure, 3″Me-EGCG recovered cell viability and increased the expression of heme oxygenase 1 (HO-1). Under ultraviolet B (UVB) and sodium nitroprusside (SNP) exposure, 3″Me-EGCG protected keratinocytes and regulated the survival protein AKT1. By regulating the AKT1/NF-κB pathway, 3″Me-EGCG augmented cell survival and proliferation in HaCaT cells. These results indicate that 3″Me-EGCG exhibits antioxidant properties, resulting in cytoprotection against various external stimuli. In conclusion, our findings suggest that 3″Me-EGCG can be used as an ingredient of cosmetic products or health supplements.</P>
Han, Sang Yun,Kim, Eunji,Hwang, Kyeonghwan,Ratan, Zubair Ahmed,Hwang, Hyunsik,Kim, Eun-Mi,Kim, Doman,Park, Junseong,Cho, Jae Youl MDPI 2018 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.19 No.5
<P>Epigallocatechin gallate (EGCG) is a well-studied polyphenol with antioxidant effects. Since EGCG has low solubility and stability, many researchers have modified EGCG residues to ameliorate these problems. A novel EGCG derivative, EGCG-5′-<I>O</I>-α-glucopyranoside (EGCG-5′Glu), was synthesized, and its characteristics were investigated. EGCG-5′Glu showed antioxidant effects in cell and cell-free systems. Under SNP-derived radical exposure, EGCG-5′Glu decreased nitric oxide (NO) production, and recovered ROS-mediated cell viability. Moreover, EGCG-5′Glu regulated apoptotic pathways (caspases) and cell survival molecules (phosphoinositide 3-kinase (PI3K) and phosphoinositide-dependent kinase 1 (PDK1)). In another radical-induced condition, ultraviolet B (UVB) irradiation, EGCG-5′Glu protected cells from UVB and regulated the PI3K/PDK1/AKT pathway. Next, the proliferative effect of EGCG-5′Glu was examined. EGCG-5′Glu increased cell proliferation by modulating nuclear factor (NF)-κB activity. EGCG-5′Glu protects and repairs cells from external damage via its antioxidant effects. These results suggest that EGCG-5′Glu could be used as a cosmetics ingredient or dietary supplement.</P>