• 한국식품과학회지
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• 제54권3호
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• pp.272-279
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• 2022

본 연구에서는 감광제에 의한 폴리페놀의 갈변 정도 및 폴리페놀 함량의 변화와 산화방지활성과 ROS 생성을 분석하였다. 그 결과 감광제에 의해 갈산과 타닌산의 자동산화가 현저히 가속화 되었으며, 타닌산에서 그 효과가 더욱 두드러졌다. 폴리페놀 함량은 산화가 진행됨에 따라 유의적으로 감소하였으나, 감광제에 농도에 의한 유의적인 차이는 EB에 의해서만 나타났으며, ABTS 라디칼 소거능 변화에서도 유사한 양상을 보였다. 갈산과 타닌산에서 ROS 생성의 증가는 명소에서 감광제 존재 하에 농도 유의적으로 증가하였다. 본 연구 결과는 폴리페놀이 감광제와 함께 빛에 노출 시 폴리페놀의 산화를 촉진시키며, 식품의 가공 및 저장 시 이들의 상호작용을 통한 품질저하 및 생리활성 변화에 주의할 필요가 있음을 시사한다.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book I
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• pp.499-500
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• 2003

To investigate the potency of some natural extracts as skin whitening agents, in this study, 25 natural plants were prepared from natural sources including medicinal plants, such as Angelica dahurica using methylene dichloride, ethyl acetate, n-butyl alcohol, and water as the extraction and/or the partitioning solvents. These natural extracts were subsequently subjected to in-vitro DOPA auto-oxidation test in the media containing human or mushroom tyrosinase as the oxidation promoting enzymes. Most of the extracts showed relatively higher enzyme inhibition(omitted)

• 한국자동차공학회논문집
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• 제11권2호
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• pp.134-139
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• 2003

This study was carried out to investigate the aging and conversion characteristics of oxidation catalysts for a natural gas vehicle with lean-bum system. The conversion of $CH_4$ was observed over the various composition ratio of PMs(Precious metals) and washcoating methods. On the fresh catalysts, Pd affected on the activity of $CH_4$ at low temperature more than other PMs in Pd-only and Rh/Pd/Pt catalysts. The activity at low temperature increased as a mount of Pd increases. On the aged catalysts, the $CH_4$ conversion efficiency of Pd-only catalyst with mono-layer washcoat decreased more than that of the other catalysts of $CH_4$ conversion. It was observed that the thermal durability of Rh/Pd/Pt catalysts with double-layer washcoat was better than the single washcoat catalyst.

• Bulletin of the Korean Chemical Society
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• 제27권12호
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• pp.2023-2027
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• 2006

Dibenzyl sulfide was oxidized at the a-carbon to yield benzaldehyde in the presence of $Pd(NO_3)_2$. Oxygen itself could not oxidize the sulfide directly, instead the nitrato ligand of the palladium complex transferred oxygen to dibenzyl sulfide to form benzaldehyde. The X-ray crystal structure of the intermediate complex, cis-[$Pd(NO_3)_2${$S(CH_2C_6H_5)_2$}$_2$], revealed that the nitrato ligand was unidentate. Para-substituted dibenzyl sulfides I, $(YC_6H_4CH_2)_2S $wherein Y = $OCH_3$, $CH_3$, Cl, CN, or $NO_2$, were synthesized and reacted with palladium nitrate, and those with electron-donating substituents (Y = $OCH_3$ and $CH_3$) were good substrates for the oxidation reaction with palladium nitrate. Thus, the reaction mechanism of the oxygen transfer was proposed to include nucleophilic benzylic carbon.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2002년도 춘계연구발표회 논문개요집
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• pp.64-65
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• 2002

• 대한화장품학회지
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• 제25권3호
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• pp.67-86
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• 1999

기능성 물질로서 다양한 생리적 기능을 가진 ascorbic acid는 구조적으로 불안정하여 쉽게 산화되는데 이러한 ascorbic acid의 산화를 억제하기 위해 리포좀에 순수한 ascorbic acid를 봉입시켜 안정한 리포좀을 제조하였다. 안정한 리포좀의 제조를 위해 cholesterol이나 $\beta$-sitosterol 이 리포좀의 안정화에 미치는 영향을 측정하였으며 ascorbic acid의 산화방지를 위해 항산화제로 butylated hydroxytoluene(BHT), tertiary butylhydroquinone(TBHQ)와 $\alpha$-glycosyl rutin, natural concentrated tocopherol을 사용하였다. 리포좀 제조시 cholesterol이나 $\beta$-sitosterol을 사용한 경우 ascorbic acid의 산화가 감소하였는데 이는 cholesterol이나 $\beta$-sitosterol이 리포좀의 이중막을 강화하여 봉입한 ascorbic acid의 방출을 감소시켜 산화를 방지하는 것으로 생각된다 또한 cholesterol의 농도가 0.3%인 경우 가장 안정한 리포좀이 생성됨을 알 수 있었다. 사용된 항산화제는 ascorbic acid에 대하여 모두 산화억제효과를 나타내었으며 tertiary butylhydroquinone, $\alpha$-glycosyl rutin, butylated hydroxytoluene, natura] concentrated tocopherol 순으로 우수함을 보였다. 그러나 제약 및 화장붐에 사용되는 ascorbic acid의 산화억제에는 효과가 가장 좋은 합성 항산화제인 tertiary butylhydroquinone보다 천연물질에서 추출한 항산화제인 $\alpha$-glycosyl rutin이 더 적합할 것으로 생각된다.

• Elastomers and Composites
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• 제54권2호
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• pp.110-117
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• 2019

The characterization of the ozone oxidation for raw natural rubber (NR) was investigated under controlled conditions through image and fourier transform infrared (FT-IR) analysis. The ozone oxidation was performed on a transparent thin film of raw NR coated on a KBr window in a dark chamber at $40^{\circ}C$ under low humidity conditions to completely exclude thermal, moisture, or light oxidation. The ozone concentration was set at 40 parts per hundred million (pphm). Before or after exposure to ozone, the image of the thin film for raw NR was observed at a right or tilted angle. FT-IR absorption spectra were measured in the transmission mode according to ozone exposure time. The ozone oxidation of NR was determined by the changes in the absorption peaks at 1736, 1715, 1697, and $833cm^{-1}$, which were assigned to an aldehyde group (-CHO), a ketone group (-COR), an inter-hydrogen bond between carbonyl group (-C=O) from an aldehyde or a ketone and an amide group (-CONH-) of protein, and a cis-methine group ($is-CCH_3=CH-$, respectively. During ozone exposure period, the results indicated that the formation of the carbonyl group of aldehyde or ketone was directly related to the decrement of the double bond of cis-1,4-polyisoprene. Only carbonyl compounds such as aldehydes or ketones seemed to be formed through chain scission by ozone. Long thin cracks with one orientation at regular intervals, which resulted in consecutive chain scission, were observed by image analysis. Therefore, one possible two-step mechanism for the formation of aldehyde and ketone was suggested.

• 한국식품영양학회지
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• 제10권4호
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• pp.564-573
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• 1997

유지류는 산화에 의해 품질이 저하되며 이를 방지하기 위해 항산화제를 첨가하는 방법이 널리 이용되어 왔다. 그러나 현재까지 많이 이용되어온 tocopherol과 BHA는 상온에서는 높은 항산화 효과가 있지만 튀김 식품과 같이 18$0^{\circ}C$이사의 고온처리가 필요한 경우에는 열안정성이 매우 낮아 이들 항상화제들의 대부분 분해되거나 산화방지 능력을 상실한다. 식물체에서 안정한 자류 라디칼을 형성할 수 있는 구조를 갖는 스테롤, 즉 곁사슬에 에틸리덴기를 갖는 citrostadienol, $\Delta$5-avenasterol과 fucosterol이 고온에서 안정한 항산화 효과가 있다고 보고되었으며 그 중에서 $\Delta$5-avenasterol 이 고온에서 가장 높은 항산화 효과가 있다고 한다. 다라서 식품의 기호성과 저장성을 높이기 위하여 고온에서 안정성을 갖는 천연 항산화제의 개발이 필요하므로 문헌 고찰을 하여 정리하였다.

• 대한한의학방제학회지
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• 제19권2호
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• pp.109-118
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• 2011

Objectives : The Lycoris squamigera Maxim has been used traditionally for treatment of various diseases. However, the studies on the effect of Lycoris squamigera Maxim have not been carried out. In the present study, extract of Lycoris squamigera Maxim were tested for their anti-inflammatory and anti-oxidation effect. Methods : The anti-inflammatory effect of the various solvent extract was studied in lipopolysaccharide (lps)-treated mouse macrophage cells. RAW 264.7 cells were pre-incubated with Lycoris squamigera Maxim extracts for 4h and treated with $1\;{\mu}g/m{\ell}$ lps for 18h, and then the anti-inflammatory effects of extracts were determined. The anti-oxidation effect of extracts measured by DPPH method, reductive potential test, total phenolics test. Results : Extracted root's ethyl acetate layer showed a significant decrease in nitric oxide. And that layer (root's ethyl acetate extract) was showed decrease in TNF-${\alpha}$ concentration dependently. Separated from Root's ethyl acetate extract was fraction 1 has $0.1{\sim}5\;{\mu}M$ range, fraction 2 has $0.1{\sim}10\;{\mu}M$ range did not showed cytotoxicity. Anti-oxidation result as DPPH test showed the best was root ethyl acetate extract. Redusing power was made a comparison between fractions and standard. They were showed similar value. Fraction's total phenol containing result was better then standard. Conclusions : These results suggest that these extracts can be used as anti-inflammatory, anti-axidation materials.

• Archives of Pharmacal Research
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• 제8권4호
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• pp.229-236
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• 1985

Oxidation of presenegenin dimethyl ester triacetate with chromium trioxide in acetic acid yielded two compounds, 11-ketone (IV) and 12-ketone (IV) derivatives. The latter was a main product. On mild alkaline hydrolysis, IV afforded 11-keto-presenegenin dimethyl ester (V), mp 232-$234^{\circ}$, $C_{32}H_{48}O_{8}$, whereas VI did 12-keto-presenegenin dimethyl ester 12, 27-hemiketal (VIII), mp 240-$242^{\circ}$, $C_{32}H_{50}O_{8}$.