• Bulletin of the Korean Chemical Society
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• 제31권3호
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• pp.595-598
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• 2010

Ab initio and DFT molecular orbital calculations predict that acetyl radical reacts with acetylene through interactions primarily involving the SOMO of the radical and the in-plane ${\pi}$-bond of acetylene. An energy barrier (${\Delta}E_1$) of 39.6 kJ $mol^{-1}$ is predicted for the preferred anti arrangement of reactants at the CCSD(T)/cc-pVDZ//BHandHLYP/cc-pVDZ level of theory. NBO analysis reveals additional interactions between the radical SOMO and the nearby C-H ${\sigma}$-bond in acetylene worth about 10% of the total transition state interaction energy. This type of orbital interaction has not previously been observed in radical addition reactions involving C-C ${\pi}$-bonds.

• 대한화학회지
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• 제26권4호
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• pp.235-246
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• 1982

본 연구에서는 자유라디칼 메카니즘에 의한 N-acetyl ${\alpha}$-aminoacrylic acid의 단독중합 반응속도와 혼성중합 반응성을 연구하였으며, DMF 용매를 사용하여 $60^{\circ}C$에서 단독중합 시켰을 때의 중합속도 ($R_p$)는 단위체 농도 [M]와 개시제 농도 [I]에 대하여 $R_p$ = $k_p[M]^{0.97}[I]^{0.59}$의 관계를 나타내었다. 또한 이 단위체의 단독중합 총괄 활성화 에너지는 25.2 kcal/mole이었다. N-acetyl ${\alpha}$-aminoacrylic acid를 아크릴산 및 스티렌 단위체와 혼성중합 시켰을 때의 단위체 반응성비는 아래와 같았다. $r_1$(N-acetyl ${\alpha}$-aminoacrylic acid) = 0.49, $r_2$(acrylic acid) = 1.41; $r_1$(N-acetyl ${\alpha}$-aminoacrylic acid) = 0.44, $r_2$(styrene) = 0.91. Alfrey-Price 식을 이용하여 계산한 N-acetyl ${\alpha}$-aminoacrylic acid의 Q와 e값은 두 경우 모두 Q=0.51, e=0.16이었다. 단독중합체 및 혼성중합체들의 열적성질을 DTA 및 TGA법으로 분석하여 비교하여 보았다.

• Journal of Microbiology and Biotechnology
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• 제16권4호
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• pp.637-638
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• 2006

Bioassay-guided fractionation of an organic extract of the culture broth from an unidentified marine-derived fungus led to the isolation of a new metabolite, N-[2-(4-hydroxyphenyl) acetyl]formamide (1), along with four known polyketides, 4-hydroxyphenyl acetamide (2), 4-hydroxyphenyl acetic acid (3), 3,4-dihydroxyphenyl acetic acid (4), and N-[2-(4-hydroxyphenyl)ethenyl]formamide (5). The structures of 1-5 were elucidated by spectral data analyses. Among them, compounds 1, 4, and 5 exhibited significant radical scavenging activity against 1, 1-diphenyl-2-picrylhydrazyl (DPPH) with $IC_{50}$ values of 8.4, 11.9, and $0.2{\mu}M$, respectively.

• 한국자원식물학회지
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• 제31권1호
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• pp.10-15
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• 2018

황칠나무 잎과 줄기를 분리하여 각각 methanol 추출하여, 계통분획상법에 따라 dichloromethane, ethyl acetate, butanol로 분획하였다. 분획물로 실시한 TLC에서 알칼로이드 성분으로 분리되는 성분을 확인할 수 있었다. 잎과 줄기 모두 ethyl acetate분획물은 $IC_{50}$ $30{\mu}g/m{\ell}$으로 높게 측정 되었으며, ethyl acetate, dichloromethane, butanol분획물 순으로 저해 활성이 높게 나타났다. Acetyl cholinesterase inhibition assay를 실시한 결과 황칠나무 잎과 줄기 모두 dichloromethane, ethyl acetate, butanol 분획물 순으로 저해 활성이 높은 것으로 나타났으며, 가장 높은 활성을 보인 황칠나무 줄기와 잎의 dichloromethane 분획물의 알칼로이드 함량이 상대적으로 높은 것으로 보아 알칼로이드 성분에 의한 것으로 유추 할 수 있으므로, 알칼로이드 성분의 동정 및 성분구조의 규명을 통하여 AChE저해 활성을 이용한 신경관련 질환에 도움을 줄 수 있는 천연물의 개발이 가능할 것으로 사료된다.

• Archives of Pharmacal Research
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• 제22권1호
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• pp.81-85
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• 1999

Nine flavonoids (1-9) were isolated from the leaves of Morus alba (Moraceae). The structures of compounds were determined to be kaempferol-3-O-$\beta$-glucopyranoisde (astragalin, 1) kaempferol-3-O-(6"-O-acetyl)-$\beta$-D-glucopyranoside (2), quercetin-3-O-(6"-O-acetyl)-$\beta$-D-glucopyranoside (3), quercetin-3-O-$\beta$-D-glucopyranoside (4), kaempferol-3-O-$\alpha$-L-rhamnopyranosyl-(1 6)-$\beta$-D-glucopyranoside (5), quercetin-3-O-$\alpha$-L-rhamnopyranosyl-(1 6)-$\beta$-D-glucopyranoside (rutin, 6), quercetin-3-O-$\beta$-D-glucopyranosyl-(1 6)-$\beta$-D-glucopyranoside (7), quercetin-3,7-di-O-$\beta$-D-glucopyranoside (8) and quercetin (9) on th basis of spectroscopic and chemical studies. Compounds 7 and 9 exhibited significant radical scavenging effect on 1,1-diphenyl-2-picryl-hydrazyl radical.

• Bulletin of the Korean Chemical Society
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• 제6권5호
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• pp.284-287
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• 1985

Cyanoisopropyl radical derived from azobisisobutyronitrile (AIBN) by either thermolysis or photolysis reacts with oxygen to give cyanoisopropylperoxy radical which then was converted to acetone and cyano radical and/or acetyl cyanide and methyl radical. Of these products, acetone formed was quantitatively determined by the addition of thianthrene cation radical perchlorate to the reaction mixture. The results showed that 55.7 mmol, 16.9 mmol, and 16.0 mmol of acetone were formed for 7 hours from 1 mol of AIBN at $82{\pm}1^{\circ}C$ in acetonitrile, carbon tetrachloride, and benzene, respectively. However, 22.2 mmol of acetone was formed from photolysis of 1 mmol of AIBN in acetonitrile. The value decreased to 13.2 mmol by bubbling argon into the solvent prior to photolysis.

• Food Science and Biotechnology
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• 제15권3호
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• pp.437-440
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• 2006

To explore the possible usefulness of ${\beta}$-glucans as natural antioxidants, the antioxidant profiles of ${\beta}$-glucan, extracted from Saccharomyces cerevisiae KCTC 7911, and water soluble and insoluble mutant ${\beta}$-glucan, isolated from yeast mutant S. cerevisiae IS2, were examined by five different in vitro evaluation methods: lipid peroxidation value (POV), nitric oxide (NO), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, reducing power, and ${\beta}$-carotene diffusion assay. The antioxidant activities of all ${\beta}$-glucans evaluated in POV test were comparable to or better than that of the known antioxidant, vitamin C. Remarkably, the ${\beta}$-glucan and water insoluble mutant ${\beta}$-glucan possessed 2.5-fold more potent activity than vitamin C at a dosage of 2 mg. Although vitamin C showed 100-fold greater activity than all ${\beta}$-glucans in NO and DPPH tests for measuring the radical scavenging capacity, all ${\beta}$-glucans revealed higher radical scavenging activity than the known radical scavenger, N-acetyl-L-cysteine (NAC), in DPPH test. The water insoluble mutant ${\beta}$-glucan had 2.6- and 5-fold greater antioxidative activity than water soluble ${\beta}$-glucan in NO and DPPH tests, respectively, showing that all ${\beta}$-glucans were able to scavenge radicals such as NO or DPPH. While all ${\beta}$-glucans revealed lower antioxidant profiles than vitamin C in both reducing power activity and ${\beta}$-carotene agar diffusion assay, the ${\beta}$-glucan and water insoluble mutant ${\beta}$-glucan did show a marginal reducing power activity as well as a considerable ${\beta}$-carotene agar diffusion activity. These results confirmed the potential usefulness of these ${\beta}$-glucans as natural antioxidants.

• Natural Product Sciences
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• 제12권2호
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• pp.94-100
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• 2006

The essential oil (EC-oil) obtained from the buds of Eugenia caryophyllata (Myrtaceae) was examined for its free radical-scavenging activity, cytotoxicity, and in vivo toxicity. To find the xenobiotic properties of EC-oil, serum thiobarbituric acid reactive substances (TBARS) level and hepatic drug-metabolizing enzyme activities were measured. It was found that EC-oil displayed xenobiotic properties like bromobenzene. The cytotoxicities of eugenol and of the EC-oil were greatly attenuated by the sulfhydryl-containing N-acetyl-L-cysteine (NAC), suggesting that eugenol was susceptible to nucleophilic sulfhydryl. In addition, eugenol also showed potent free radical-scavenging activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Moreover, methyleugenol considerably exhibited less cytotoxicity and less potent free radical-scavenging activity than eugenol, and the cell viability of the methyleugenol was more increased with NAC treatment than the eugenol. These results indicate that the phenolic OH in eugenol may play a crucial role in both cytotoxicity and free radical-scavenging activity. The fashion on oxidative stress and hepatic drug-metabolizing enzyme activities of eugenol resembled those of bromobenznene.

• 한국식품영양과학회지
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• 제37권5호
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• pp.542-547
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• 2008

본 연구에서는 제2형 당뇨병를 가진 GK 흰쥐(Goto-Kakizaki) 간에서 추출한 cytosol과 심장에서 추출한 mitochondria를 이용한 모델계에서 당대사 관련 효소인 glucokinase glucokinase(GCK), pyruvate dehydrogenase(PDH), acetyl-CoA carboxylase(ACC) 및 glucosidase 활성에 대한 한약재의 물 추출물의 항당뇨 효과를 연구하였다. 그리고 역시 그들의 물 추출물의 free radical 소거활성을 DPPH 방법으로 알아보았다. Free radical 소거활성은 산수유(CF), 목단피(MDB), 천화분(CHB) 그리고 산약(SY)의 물 추출물이 강했고 반면에 백목령(BBR), 숙지황(SGH)과 택사(TS)는 낮은 소거작용을 나타내었다. 간 cytosol의 GCK 활성은 산수유(CF)와 천화분(CHB)에서 다른 추출물보다 더 강했다. 심장미토콘드리아의 PDH 활성은 택사(TS)를 제외하고 모든 추출물에서 대조군과 비교하여 높았다. 간 cytosol의 ACC 활성은 대조군보다 산수유(CF), 천화분(CHB), 숙지황(SGH), 택사(TS) 그리고 산약(SY) 추출물에서 높았다. 산수유(CF), 백복령(BBR) 및 목단피(MDB) 추출물은 ${\alpha}$-glucosidase 활성 감소를 유도했다. 따라서 모든 추출물은 혈당 상승을 억제할 수 있는 항당뇨 기능성식품이나 약품 개발을 위한 기능성 천연 소재로 이용될 수 있을 가능성을 제시하였다.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1998년도 Proceedings of UNESCO-internetwork Cooperative Regional Seminar and Workshop on Bioassay Guided Isolation of Bioactive Substances from Natural Products and Microbial Products
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• pp.182-182
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• 1998

The root of Aralia continentalis Kitagawa(Araliaceae) have been used as an analgesic and fever remedy, and for treatment of rheumatism in Chinese medicine, whereas the young leaves are used for salad. An antioxidant activity of the young leaves of A continentalis was determined by measuring lipid peroxide produced when a mouse liver homogenate was exposed to the air at 37$^{\circ}C$, using 2-thiobarbituric acid(TBA) and by evaluation the radical scavenging activity on 1,l-diphenyl-2 picrylhydrazyl (DPPH) radical. Bioassay guided fractionation of MeOH extract isolated six flavonoid compounds as active components from EtOAc fraction. Adenosine and two saponins were isolated from the weak active BuOH fraction. The antioxidant effect by DPPH radical scavenging activity showed that quercetin was the most active among these compounds. Hyperoside and kaempferol were also active, while 6"-O-acetyl astragalin, astragalin, trifolin, adenosine, oleanolic acid 28-O-glucosyl ester and salsoloside C methyl ester were almost inactive. All the compounds were identified by spectroscopic methods.