Effect of Alkali Metal Ions on Nucleophilic Substitution Reactions of 4-Nitrophenyl X-Substituted Benzoates with Alkali Metal Ethoxides in Anhydrous Ethanol

Jin-A Seo,Song-I Kim,Yeon-Ju Hong,엄익환 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.2

Pseudo-first-order rate constants (kobsd) have been measured spectrophotometrically for nucleophilic substitution reactions of 4-nitrophenyl benzoate (5a), 4-nitrophenyl 4-methoxybenzoate (5b), and 4-nitrophenyl 4-hydroxybenzoate (5c) with alkali metal ethoxides, EtO–M+ (M+= Li+, Na+ and K+) in anhydrous ethanol (EtOH) at 25.0 ± 0.1 oC. The plots of kobsd vs. [EtO–M+] exhibit upward curvatures in all cases, indicating that M+ ions catalyze the reactions and ionpaired EtO–M+ species are more reactive than dissociated EtO–. Second-order rate constants for reactions with dissociated EtO– and ion-paired EtO–M+ (i.e., kEtO– and kEtO–M+, respectively) have been calculated from ion-pair treatment for the reactions of 5a and 5b. However, such ion-pair treatment has failed to determine kEtO– and kEtO–M+ values for the reactions of 5c. It has been concluded that reactions of 5a and 5b are catalyzed by one metal ion, which increases electrophilicity of the reaction center through coordination on the carbonyl oxygen. In contrast, reactions of 5c have been suggested to involve two metal ions, i.e., the one coordinated on the carbonyl oxygen increases the electrophilicity of the reaction center while the other one associated on the phenoxy oxygen decreases the charge repulsion between the anionic reagents (i.e., EtO– and deprotonated 5c). It has been found that the rate equation derived from the mechanism involving two metal ions fits nicely to the kinetic results obtained for the reactions of 5c.

Effect of Alkali Metal Ions on Nucleophilic Substitution Reactions of 4-Nitrophenyl X-Substituted Benzoates with Alkali Metal Ethoxides in Anhydrous Ethanol

Seo, Jin-A,Kim, Song-I,Hong, Yeon-Ju,Um, Ik-Hwan Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.2

Pseudo-first-order rate constants ($k_{obsd}$) have been measured spectrophotometrically for nucleophilic substitution reactions of 4-nitrophenyl benzoate (5a), 4-nitrophenyl 4-methoxybenzoate (5b), and 4-nitrophenyl 4-hydroxybenzoate (5c) with alkali metal ethoxides, $EtO^-M^+$ ($M^+=Li^+$, $Na^+$ and $K^+$) in anhydrous ethanol (EtOH) at $25.0{\pm}0.1^{\circ}C$. The plots of $k_{obsd}$ vs. [$EtO^-M^+$] exhibit upward curvatures in all cases, indicating that $M^+$ ions catalyze the reactions and ionpaired $EtO^-M^+$ species are more reactive than dissociated $EtO^-$. Second-order rate constants for reactions with dissociated $EtO^-$ and ion-paired $EtO^-M^+$ (i.e., $k_{EtO^-}$ and $k_{EtO^-M^+}$, respectively) have been calculated from ion-pair treatment for the reactions of 5a and 5b. However, such ion-pair treatment has failed to determine $k_{EtO^-}$ and $k_{EtO^-M^+}$ values for the reactions of 5c. It has been concluded that reactions of 5a and 5b are catalyzed by one metal ion, which increases electrophilicity of the reaction center through coordination on the carbonyl oxygen. In contrast, reactions of 5c have been suggested to involve two metal ions, i.e., the one coordinated on the carbonyl oxygen increases the electrophilicity of the reaction center while the other one associated on the phenoxy oxygen decreases the charge repulsion between the anionic reagents (i.e., $EtO^-$ and deprotonated 5c). It has been found that the rate equation derived from the mechanism involving two metal ions fits nicely to the kinetic results obtained for the reactions of 5c.

초임계 Tetrahydrofuran 에 의한 SBR 과 폐타이어의 분해공정

홍인권,김성덕,김원일,김형진,정수경 한국공업화학회 1998 응용화학 Vol.2 No.2

The waste tire and the styrene-butadiene rubber were depolymerized in a supercritical tetrahydrofuran, respectively, TGA thermograms of the waste tire and residue were divided into two regions: First, weight loss region by decomposition of the styrene-butadiene. Second, the region by decomposition of low molecular weight materials. The average molecular weight of both products from the styrene-butadiene rubber and the waste tires decreased, as process variables such as temperature, pressure and time incresed. So it was possible to depolymerize the styrene-butadiene rubber and the waste tires with low temperature process around 300℃ in supercritical fluid process and recover oil with low molecular weight.

김치 관련 연구문헌의 분류분석 및 김치연구의 동향 (Ⅲ)

최홍식,김재이,민병태,전정태,공연희,홍정진,김나영 부산대학교 김치연구소 2002 김치의 과학과 기술 Vol.8 No.-

About 200 research papers and patents on kimchi(Korean fermented vegetable food) published In the years of 1997-2001 were collected and analyzed for the classification and review. This article covers the classified topics on the natures and kinds of raw materials, fermentation and related microorganisms, processing / preservation, kimchi packaging, biochemical changes, enzymes, quality, food chemistry, functional klmchi, general consideration on kimchi, and also some research nerds In the future.

맥엽 및 항산화 조성물의 생리 기능적 특성에 관한 연구 : 아질산염 소거능을 중심으로 Study on the Nitrite Scavenging Effect

이성희,홍이진,박형근,주상섭,김경탁 한국응용생명화학회 2003 Applied Biological Chemistry (Appl Biol Chem) Vol.46 No.4

맥엽과 이를 이용한 항산화 조성물을 제조하여 이에 존재하는 nitrite scavenging 효과와 이에 따른 발암원으로 부터의 보호 효과를 조사한 결과는 다음과 같다. 맥엽과 항산화 조성물 모두 수층에 비하여 메탄올층에서 아질산염 소거능이 2배 이상 높게 나타나 M-BL50의 0.01㎎/㎖ 농도에서 약 64.3%, M-AM 0.01㎎/㎖의 처리군이 이보다 약간 높은 68.3% 정도로 나타내었다. 마우스 단핵구 기원인 RAW 264.7(macrophage, mouse)에 맥엽과 항산화 조성물의 수층과 메탄올층을 처리하고 세포 생존율을 측정한 결과 수층 처리군에 비해 메탄올층 처리군에서 모두 세포 생존율이 더 낮게 측정되었으며 모든 시료에서 농도의존적으로 세포 증식이 억제되었다. 특히, M-AM을 처리한 군의 경우 모든 농도에서 가장 낮은 세포 생존율을 나타내어 항산화물 첨가에 의해 세포 증식 억제 효과가 상승됨을 알 수 있었으며, IC_(50) 수치 또한 메탄올층과 A-AM 시료 처리군에서 현저히 낮은 수치를 나타내었다. 또한 세포 내 아질산염 소거능을 측정한 결과 역시 마찬가지로 맥엽 입자 크기에 따른 차이는 나타나지 않았으며 수층 처리군에 비해 메탄올층 처리군과 항산화물을 첨가한 군에서 모두 높은 소거능을 나타내어 맥엽 및 기타 항산화물을 섭취함으로써 체내에서의 니트로사민 생성을 억제시킬 수 있을 것으로 예상된다. This study was conducted to estimate the biofunctional characteristics, namely nitrite scavenging effect of barley leaves (BL) and their mixture (AM) with other antioxidants. Aqueous or methanol extracts were obtained from BL and AM. Aqueous and methanol extracts from barley leaves had relatively higher nitrite scavenging effects and its activities and contents increased in a concentration-dependent manner. The activities and contents of methanol extracts obtained from BL and AM were higher than those of aqueous extracts. Especially, AM containing BL and other antioxidant mixture had the highest activities and contents increased in a concentration-dependent manner. BL or AM were added to macrophage cells of RAW 264.7 Survival rates of the cells treated with BL and AM were measured to be different. IC_(50) value decreased in a concentration-dependent manner by the addition of aqueous or methanol extracts from BL and AM. Especially, methanol extracts of AM had the highest nitrite scavenging effects. Thus, BL and AM may have protective effect against carcinogen and immune ability against reactive molecules through NO (nitric oxide) signal pathway. From the above results, barley leaves appear to contain natural anticancer and immune-related agents and may have potentiality to be used as functional food ingredients.

NOAA-AVHRR 자료를 이용한 1km 해상도 벼논 피복의 간이분류법

구자민,홍석영,윤진일 한국농림기상학회 2001 한국농림기상학회지 Vol.3 No.4

Land surface parameterization schemes for atmospheric models as well as decision support tools for ecosystem management require a frequent updating of land cover classification data for regional to global scales. Rice paddies have not been treated independently from other agricultural land classes in many classification systems, despite their atmospheric and ecological significance. A simple but improved method over conventional land cover classification schemes for rice paddy is suggested. Normalized difference vegetation index (NDVI) was calculated for the land area of South Korea at a 1㎞ by 1㎞ resolution from the visible and the near-infrared channel reflectances of NOAA-AVHRR (Advanced Very High Resolution Radiometer). Monthly composite images of daily maximum NDVI were prepared for May and August, and used to classify 4 major land cover classes: urban, farmland, forests and water body. Among the pixels classified as "forests" in August, those classified as "water body" in May were assigned a "rice paddy" class. The distribution pattern of "rice paddy" pixels was very similar to the reported rice acreage of 1,455 Myons, which is the smallest administrative land unit in Korea. The correlation coefficient between the estimated and the reported acreage of Myons was 0.7, while 0.5 was calculated from the USGS classification.

Evaluation of Bovine Pregnant Serum Proteins

Hye Ran Lee,Hong Rye Kim,Ho Jun Lee,Jong Taek Yoon,Chang Sik Park,Dong I1 jin 한국동물생명공학회(구 한국동물번식학회) 2006 Reproductive & developmental biology Vol.30 No.2

Evaluation of Bovine Pregnant Serum Proteins

Hye Ran Lee,Hong Rye Kim,Ho Jun Lee,Jong Taek Yoon,Chang Sik Park,Dong I1 jin 한국동물번식학회 2006 Reproductive & Developmental Biology(Supplement) Vol.30 No.2s

Caspase-3을 경유한 동충하초 자실체 유래 4-Acetyl-12, 13-epoxyl-9-trichothecene-3, 15-diol의 방광암 세포주(NBT-II) Apoptosis

김형진,장선일,오기수,홍경환,김윤철,배현옥,윤용갑,정헌택,권태오,Kim Hyeong-Jin,Jang S.I.,Oh K,S.,Hong K.H.,Kim Y.C.,Pae H.O.,Yun Y.G.,Chung H.T.,Kwon T.O. 대한한의학방제학회 2002 大韓韓醫學方劑學會誌 Vol.10 No.2

The fruiting bodies of Isaria japonica have been traditionally used in Korea to treat cancer. An apoptosis-inducing compound, 4-Acetyl-12, 13-epoxyl -9-trichothecene-3, I5-diol (AETD), was isolated from the methanol extract of fruiting bodies of Isaria japonica Yasuda by bioassay -guided fractionation. The apoptosis of murine bladder cancer cell line (NBT-Ⅱ) by the compound was accessed by propidium iodide staining flow cytometric analysis, and apoptosis-inducing activity at $IC_{50}$ concentration (5 nmol/L) was further confirmed by a nuclear morphological change, a ladder pattern of DNA fragmentation, and an activation of caspase-3. These results indicate that AETD induces apoptosis of NBT-Ⅱ cells via expression of caspase-3.

Identification of sterols from the soft coral <i>Dendronephthya gigantea</i> and their anti-inflammatory potential

Fernando, I.P.Shanura,Sanjeewa, K.K.Asanka,Kim, Hyun-Soo,Kim, Seo-Young,Lee, Seung-Hong,Lee, Won Woo,Jeon, You-Jin Elsevier 2017 Environmental toxicology and pharmacology Vol.55 No.-

<P><B>Abstract</B></P> <P>Exploration of anti-inflammatory phytochemicals has received tremendous attention worldwide owing to the rapid increase in inflammatory diseases. Current study reveals the identification of eight 3β-hydroxy-Δ<SUP>5</SUP>-steroidal congeners from a nonpolar column fraction of the ethanol solubles from the soft coral <I>Dendronephthya gigantea</I> collected from Jeju Island South Korea, using GC–MS/MS analysis. The sterol-rich fraction (DGEH21) showed a significant anti-inflammatory activity as exhibited by the inhibition of NO production (IC<SUB>50</SUB> 4.33±0.50μg/mL) and PGE<SUB>2</SUB> production in LPS-stimulated RAW 264.7 macrophages. It also suppressed the expression levels of proinflammatory cytokines, TNF-α, IL-1β, and IL-6 in a dose-dependent manner. Furthermore, DGEH21 effectively downregulated the expression levels of iNOS, and COX-2 and reduced NO and ROS production as well as cell death in LPS-stimulated <I>in-vivo</I> zebrafish embryo model. However, DGEH21 at relatively high concentrations indicated cytotoxicity in both RAW cells and zebrafish embryos with RAW cell viability being nearly 80% after treatment with 25μg/mL DGEH21. This study highlights the synergistic anti-inflammatory activity of several steroids found in <I>D. gigantea</I>. Their actions may be useful in the development of anti-inflammatory cosmeceuticals, pharmaceutical agents, and other consumer products.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Eight 3β-hydroxy-Δ5-steroidal congeners were identified from the <I>Dendronephthya gigantea</I>. </LI> <LI> Synergistically the sterols indicated a profound anti-inflammatory potential in LPS-induced RAW cells. </LI> <LI> Sterols downregulated inflammatory mediators in LPS-induced RAW cells. </LI> <LI> Indicated anti-inflammatory effects in in vivo LPS-induced zebra fish model. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>