• Biomolecules & Therapeutics
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• 제29권3호
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• pp.321-330
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• 2021

Oxidative stress plays a crucial role in the development of neuronal disorders including brain ischemic injury. Thioredoxin 1 (Trx1), a 12 kDa oxidoreductase, has anti-oxidant and anti-apoptotic functions in various cells. It has been highly implicated in brain ischemic injury. However, the protective mechanism of Trx1 against hippocampal neuronal cell death is not identified yet. Using a cell permeable Tat-Trx1 protein, protective mechanism of Trx1 against hydrogen peroxide-induced cell death was examined using HT-22 cells and an ischemic animal model. Transduced Tat-Trx1 markedly inhibited intracellular ROS levels, DNA fragmentation, and cell death in H2O2-treatment HT-22 cells. Tat-Trx1 also significantly inhibited phosphorylation of ASK1 and MAPKs in signaling pathways of HT-22 cells. In addition, Tat-Trx1 regulated expression levels of Akt, NF-κB, and apoptosis related proteins. In an ischemia animal model, Tat-Trx1 markedly protected hippocampal neuronal cell death and reduced astrocytes and microglia activation. These findings indicate that transduced Tat-Trx1 might be a potential therapeutic agent for treating ischemic injury.

• 한국자원식물학회지
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• 제32권3호
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• pp.220-227
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• 2019

Stevia rebaudiana (Asteraceae), a perennial plant, has been used as a low-calorie sweetener and is being developed as a therapeutic agent for diabetes, hypertension, myocardial diseases, and microbial infections. Despite the common use of its leaves and stem, the bioavailability of the components present in S. rebaudiana flowers, when used as ingredients of cosmetics, has not been well investigated. Herein, we investigated the antioxidative and antimelanogenic effects of an aqueous extract of S. rebaudiana flowers (Stevia-F). Total flavonoid and phenolic content in Stevia-F were determined to be $8.64{\pm}0.23mg$ of quercetin equivalents/100 g and $631.5{\pm}2.01mg$ of gallic acid equivalents/100 g, respectively. The $IC_{50}$ values of Stevia-F for reducing power, and 2,2-diphenyl-1-picryl-hydrazyl-hydrate radical, hydrogen peroxide, and nitric oxide scavenging activities were 5541.96, 131.39, 466.34, and $10.44{\mu}g/mL$, respectively. Stevia-F showed inhibitory effects on the tyrosinase ($IC_{50}=134.74{\mu}g/mL$) and ${\alpha}$-glucosidase ($IC_{50}=114.81{\mu}g/mL$) activities. No significant cytotoxicity of Stevia-F was observed in B16F10 cells, treated with up to $100{\mu}g/mL$ of the extract for 24 and 48 h (p > 0.05). Stevia-F ($1-100{\mu}g/mL$) suppressed ${\alpha}$-melanocyte stimulating hormone-induced melanin production in B16F10 cells (p < 0.05) and also inhibited the cellular tyrosinase activity (p < 0.05). Overall, our results show that Stevia-F possesses potential for inhibiting tyrosinase and ${\alpha}$-glucosidase activities and has significant antioxidant capacity. The antimelanogenic potential of Stevia-F should extend the usage of S. rebaudiana flowers in the development of skin-whitening products.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2019년도 추계학술대회
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• pp.92-92
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• 2019

Excessive or chronic inflammation contributes to the pathogenesis of many inflammatory diseases such as sepsis, rheumatoid arthritis, and ulcerative colitis. Hibiscus syriacus L. has been used as a medicinal plant in many Asian countries, even though its anti-inflammatory activity has been unclear. Therefore, we investigated the anti-inflammatory effect of anthocyanin fractions from the H. syriacus L. varieties Pulsae (PS) on the lipopolysaccharide (LPS)-induced expression of proinflammatory mediators and cytokines in RAW264.7 macrophages. PS suppressed LPS-induced nitric oxide (NO) and prostaglandin $E_2$ ($PGE_2$) secretion concomitant with downregulation of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) expression. Furthermore, PS inhibited the production of proinflammatory cytokines such as tumor necrosis factor-alpha ($TNF-{\alpha}$), interleukin-6 (IL-6), and IL-12 in LPS-stimulated RAW264.7 macrophages. Further study showed that PS significantly decreased LPS-induced nuclear translocation of the nuclear $factor-{\kappa}B$ ($NF-{\kappa}B$) subunits, p65 and p50. Molecular docking data showed that many anthocyanins from PS fit into the hydrophobic pocket of MD2 and bound to Toll-like receptor 4 (TLR4), indicating that PS inhibits the TLR4-MD2-mediated inflammatory signaling pathway. Especially, apigenin-7-O-glucoside most powerfully bound to MD2 and TLR4 through LYS122, LYS122, and SER127 at a distance of $2.205{\AA}$, $3.098{\AA}$, and $2.844{\AA}$ and SER441 at a distance of $2.873{\AA}$ (docking score: -8.4) through hydrogen bonding, respectively. Additionally, PS inhibited LPS-induced TLR4 dimerization/expression on the cell surface, which consequently decreased MyD88 recruitment and IRAK4 phosphorylation. PS completely blocked LPS-mediated mortality in zebrafish larvae by diminishing the recruitment of neutrophil and macrophages accompanied by low levels of proinflammatory cytokines. Taken together, our results indicate that PS attenuates LPS-mediated inflammation in both in vitro and in vivo by blocking the TLR4/MD2-MyD88/IRAK4-$NF-{\kappa}B$ axis. Therefore, PS might be used as a novel modulatory candidate for effective treatment of LPS-mediated inflammatory diseases.

• Bulletin of the Korean Chemical Society
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• 제22권2호
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• pp.164-170
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• 2001

The crystal structures of fully dehydrated Ni2+- and Tl+ -exchanged zeolite X (Ni17Tl58-X, and Ni12Tl68-X; X=Si100Al92O384) have been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd3 at $21(1)^{\circ}C$ (a=24.380(4) $\AA$, 24.660(4) $\AA$, respectively). Their structures have been refined to the final error indices R1=0.037 and R2=0.043 with 485 reflections, and R1=0.039 and R2=0.040 with 306 reflections, respectively, for which I >36(I). In Ni17Tl58-X, 17 Ni2+ ions per unit cell were found at only two sites: 15 at site I at the center of the hexagonal prism (Ni-O=2.203(9) $\AA)$ and the remaining 2 at site II near single six-oxygen rings in the supercage (Ni-O=2.16(3) $\AA).$ Fifty-eight Tl+ ions were found at five crystallographic sites: 28 at site II (Tl-O=2.626(8) $\AA)$, 2 at site I' in the sodalite cavity near the hexagonal prism (Tl-O=2.85(1) $\AA)$, another 2 at site II' in the sodalite cavity (Tl-O=2.77(1) $\AA).$ The remaining 26 were found at two nonequivalent Ⅲ' sites with occupancies of 23 and 3. In Ni12Tl68-X, 12 Ni2+ ions per unit cell were found at two sites: 10 at site I (Ni-O=2.37(2) $\AA)$ and the remaining 2 at site II (Ni-O=2.13(2) $\AA).$ Sixty-eight Tl+ ions were found at five crystallographic sites: 28 at site II (Tl-O=2.63(1) $\AA)$, 12 at site I' (Tl-O=2.62(1) $\AA)$, 2 at site II' (Tl-O=3.01(2) $\AA)$, and the remaining 26 at two III' sites with occupancies of 23 and 3. It appears that Ni 2+ ions prefer to occupy site I and II, in that order. The large Tl+ ions occupy the remaining sites, I', II, II' and two different III' sites. In both crystals, only the Ni2+ ions at site II were reduced and migrated to the external surface of zeolite X when these crystals were treated with hydrogen gas.

• 한국분말재료학회지
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• 제28권2호
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• pp.143-149
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• 2021

In this study, (GaN)_1-x(ZnO)_x solid solution nanoparticles with a high zinc content are prepared by ultrasonic spray pyrolysis and subsequent nitridation. The structure and morphology of the samples are investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The characterization results show a phase transition from the Zn and Ga-based oxides (ZnO or ZnGa₂O₄) to a (GaN)_1-x(ZnO)_x solid solution under an NH3 atmosphere. The effect of the precursor solution concentration and nitridation temperature on the final products are systematically investigated to obtain (GaN)_1-x(ZnO)_x nanoparticles with a high Zn concentration. It is confirmed that the powder synthesized from the solution in which the ratio of Zn and Ga was set to 0.8:0.2, as the initial precursor composition was composed of about 0.8-mole fraction of Zn, similar to the initially set one, through nitriding treatment at 700℃. Besides, the synthesized nanoparticles exhibited the typical XRD pattern of (GaN)_1-x(ZnO)_x, and a strong absorption of visible light with a bandgap energy of approximately 2.78 eV, confirming their potential use as a hydrogen production photocatalyst.

• 자원리싸이클링
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• 제31권4호
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• pp.12-18
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• 2022

우리나라는 철광석, 석탄 등 철강 산업에 사용되는 원료를 수입에 크게 의존하고 있다. 이러한 원자재는 글로벌 철강산업의 원가, 생산성, 품질경쟁력에 큰 영향을 미친다. 따라서 철강사의 경쟁력을 확보하기 위해서는 원자재의 수입 의존도를 줄이는 것이 필요하며, 원료 의존도를 낮추기 위해서는 Fe를 함유한 부산물을 활용하는 것이 좋은 방법이 될 수 있다. Fe 함유 부산물은 주로 철강 산업에서 발생하며 Fe 함량이 높으나(40~70%) 매우 미세한 분말 형태를 가지고 있다. 이러한 미세한 분말을 플랜트 공정에 직접 사용할 경우 부산물이 비산되어 조업과 환경에 나쁜 영향을 미칠 수 있다. 따라서 Fe 함유 부산물을 광범위하게 사용하기 위해서는 보다 큰 형태로 전처리할 필요가 있다. 이를 위해 펠렛 및 브리켓과 같은 더 큰 모양을 만들어 사용하는 것이다. 브리켓을 만드는 방법은 대표적으로 두 가지 방법이 있다. 첫번째는 열과 압력을 가하여 핫브리켓을 제조하는 방법이고, 두번째는 열을 사용하지 않고 소량의 바인더와 압력을 가해 냉간 브리켓을 제조하는 방법이다. 본 연구에서는 Fe 함유 부산물을 이용하여 고강도 냉간 브리켓을 가장 효율적으로 제조하기 위한 방법을 연구하였고, 다양한 조건에서 성형율과 브리켓 강도를 조사하여 최적의 제조 조건을 도출하였다.

• 대한약침학회지
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• 제25권3호
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• pp.216-223
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• 2022

Objectives: Oxidative stress plays a key role in chronic and acute brain disorders and neuronal damage associated with Alzheimer disease (AD) and other neurodegeneration symptoms. The neuroprotective effects of berberine and Berberis vulgaris (barberry) root extract against apoptosis induced by hydrogen peroxide (H₂O₂) in the human SH-SY5Y cell line were studied. Methods: The methanolic extraction of barberry root was performed using a maceration procedure. Oxidative stress was induced in SH-SY5Y cells by H₂O₂, and an MTT assay was applied to evaluate the neuroprotective effects of berberine and barberry root extract. The cells were pretreated with the half maximal inhibitory concentration (IC₅₀) of each compound (including berberine, barberry root extract, and H₂O₂), and the anti-apoptotic effects of all components were investigated using RT-PCR. Results: The SH-SY5Y cell viability increased in both groups exposed to 75 and 150 ppm barberry extract compared with that in the H₂O₂-treated group. The data showed that exposing SH-SY5Y cells to 30 ppm berberine significantly increased the cell viability compared with the H₂O₂-treated group; treatment with 150 and 300 ppm berberine and H₂O₂ significantly decreased the SH-SY5Y cell viability and was associated with berberine cytotoxicity. The mRNA levels of Bax decreased significantly under treatment with berberine at 30 ppm compared with the control group. A significant increase in Bcl-2 expression was observed only after treatment with the IC₅₀ of berberine. The expression level of Bcl-2 in cells exposed to both berberine and barberry extracts was also significantly higher than that in cells exposed to H₂O₂. Conclusion: The outcomes of this study suggest that treatment of SH-SY5Y cells with barberry extract and berberine could suppress apoptosis by regulating the actions of Bcl-2 family members.

• 자원환경지질
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• 제55권1호
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• pp.45-51
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• 2022

독도에서의 "인간의 거주 혹은 독자적인 경제활동을 영위할 수 있는가의 여부"는 국제법 상으로 독도의 지위를 결정하는 중요한 요소로 작용한다. 이러한 관점에서 독도의 활용가능한 물(water resource)에 대하여, 독도에서 유일하게 지하수 유출이 발생하고 있는 서도의 물골을 대상으로 조사한 수문학적 결과를 보고한다. 이 조사에서 평가한 물골의 지하수 유출량은 최소 1.1 m³/d로 나타났으며, 이는 기존의 연구들에서 제시한 결과와 통계적으로 유사하다. 물의 산소-수소 안정동위원소비를 통한 기원 분석에서 지하유출수의 기원은 강수로 판단되며, 일강수량을 기준으로 할 때, 강수의 약 36% 정도는 화산암 내의 절리를 통해 빠르게 지하수로 유출된다. 지하유출수의 수질은 생활용수와 음용수로 사용하기에는 높은 염도와 질산염 농도를 보이며, 이들은 해무와 파도 등에 의한 염분과 괭이 갈매기 등 조류 배설물로부터 기인된 것으로 판단된다.

• 한국결정성장학회지
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• 제32권2호
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• pp.77-82
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• 2022

고효율의 수전해 촉매는 낮은 전압에서 빠른 속도로 산화반응이 가능하기에 반응 활성이 높은 촉매설계 및 제조 공정이 필요하다. 현재 귀금속 촉매가 산소 발생 반응 성능에 있어서 우수한 특성을 보여주고 있지만 높은 가격과 낮은 반응성에 의한 효율 한계성으로 인해 상용화에 큰 어려움을 겪고 있다. 최근 귀금속 촉매를 대체하기 위해 저비용/고효율 수전해 촉매 개발연구가 활발하게 진행되고 있는데, 본 연구에서는 가격적인 측면에서 부담이 적고 산소활성 반응이 뛰어난 니켈 금속과 전기전도성이 뛰어난 multi walled carbon nanotube(MWCNT)를 이용하고 pulsed laser ablation in Liquid(PLAL) 공정을 적용하여 MWCNT 구조내에 Ni 을 성공적으로 dopping하여 Ni-MWCNT 촉매를 제작하고자 하였다. High resolution-transmission electron microscopy(HR-TEM) 분석 및 X-ray photoelectron spectroscopy(XPS) 분석을 통하여 개발된 수전해 촉매의 구조 및 화학적 조성을 확인하였으며, 촉매 산소발생반응 평가는 선형 주사 전위법(Linear sweep voltammetry; LSV) 과전압 특성, 타펠 기울기(Tafel slope), 전기화학 임피던스 분광법(Electrochemical impedance spectroscopy; EIS), 순환 전압 전류법(Cyclic voltammetry; CV) 및 Chronoamperometry(CA) 측정법으로 진행하였다.

• 분석과학
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• 제19권6호
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• pp.482-489
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• 2006

Pediococcus에서 추출된 lactate oxidase(LOD)를 poly(vinyl alcohol)(PVA)에 고정화하여 2전극계로 구성된 lactate 바이오센서를 제조하였다. Lactate는 LOD 효소와의 반응에서 생성되는 $H_2O_2$를 전기화학적으로 금(Au)위에 형성시킨 Pt-black 층에서 산화시켜 정량 할 수 있었다. Pt-black으로 만들어진 센서는 과산화수소에 대해서 낮은 전위(+300 mV vs. Ag/AgCl)에서 큰 산화전류를 보여주었으며, ascorbic acid, acetaminophen, uric acid 등과 같이 산화되기 쉬운 산화 종들의 영향을 감소시켜주었다. 외부보호막으로는 다양한 종류의 친수성 폴리우레탄을 사용하였다. 센서는 in vitro 방식으로 흐름계와 비흐름계 모두에서 성능을 평가하였다. 제작된 센서는 0.05 M NaCl을 포함하는 0.05 M 인산염 완충용액(pH 7.6)에서 성능을 시험하였으며, 0.1 mM에서 9.0 mM의 lactate 농도구간에서 직선적 감응성을 나타내었다. 최적화된 센서는 $4^{\circ}C$ 완충용액에 보관하였으며, 25일 이상 감응도(sensitivity)가 거의 변화하지 않았다.