• 한국환경농학회지
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• 제30권1호
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• pp.82-88
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• 2011

현재 우리나라에서 널리 이용되고 있는 미생물학적 검사법을 이용하여 TCs 계열의 모화합물과 epimer에 대한 검출 그리고 이를 통한 모화합물과 epimer간의 상대적 생물학적 활성도를 확인하였다. 시험법의 관점에서 낮은 선택성과 낮은 민감도를 나타낸 균주는, 다양한 적용 가능 균주의 발굴 및 적용이 시험법 검증을 통해 이루어질 필요가 있다. 극단적으로 식품 중 epimer만이 잔류하여 미생물 시험에서 의양성이 나올 경우, 기기분석을 통해 확인 정량시 원물질이 검출되지 않는다면, 이는 분석화학과 독성학의 과학적 지식을 바탕으로 볼 때 제도적 맹점으로도 남을 수도 있다. 그리고, 현행 우리나라의 모화합물에 국한 된 잔류허용 기준은 활성이 있는 epimer나 대사산물까지 확대하여 검토 해 볼 필요가 있으며, 이는 최근 의약품류의 환경 중 잔류실태 조사, 환경 중 위해성 평가 및 관리를 위해서도 관리 대상물질을 과학적 근거에 따라 제시해 주는 중요한 자료가 된다.

• 한국식품위생안전성학회지
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• 제15권4호
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• pp.287-292
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• 2000

1976년과 1997년 남해안의 거제도 외포리에서 채취한 진주담치와 굴의 독력 덴 독소성분을 비교 조사하였다. 독성은 진주담치가 굴에 비하여 약 10배 정도 높았으며(1996년, 진주담치, 8,670 $\mu\textrm{g}$, 굴 860$\mu\textrm{g}$; 1997년, 진주담치 5,657 $\mu\textrm{g}$, 굴 531$\mu\textrm{g}$/100g), 독화기간도 진주담치가 굴에 비하여 길었다. 두 종류의 시료 모두 독소 주성분은 Cl 및 C2 (20~65%)와 gonyautoxin 1, 2, 3, 4 (38~78%)이었다. 그리고 독화초기에는 11$\beta$-epimer toxin(C2, GTX4)의 비율이 25~56mo1e%(1996년)와 25~80mo1e% (1997년)로 11$\alpha$-epimer toxin(Cl, GTX2)의 비율도다 높았다. 그러나 독화기간이 지남에 따라 11$\alpha$-epimer toxin의 비율이 41~57mo1e%(1996년)와 25~56mo1e%(1997년)로 11$\beta$-epimer toxin의 비율보다 높게 나타났다. 이와 같은 독소성분 조성의 변화는 패류내에서 독소가 대사되기 때문인 것으로 추측된다.

• Bulletin of the Korean Chemical Society
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• 제22권8호
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• pp.857-866
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• 2001

Efficient syntheses of PGI2 analogue 2a and its epimer 3 have been accomplished. Using aryl iodide 6 as the common intermediate, either radical or palladium-assisted tandem alkene insertion strategies have been employed for construction of the benzoprostacyclin framework.

• Archives of Pharmacal Research
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• 제10권3호
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• pp.200-201
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• 1987

Frangufoline (sanjoinine-A) (1) was transformed into its epimer, sanjoinine-$Ah_1$(2) on heat treatment. Absolute configuration of (1) and (2) was determined.

• 약학회지
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• 제45권4호
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• pp.328-333
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• 2001

Ginsenoside Rh$_2$, a minor glycoside constituent of the red ginseng is known as an unique antitumor compound. Several attempts to prepare it in a large scale including semisynthesis from betulafolientriol, an 3-epimer of 20(S)-protopanaxadiol, has been reported. We have previously reported a synthesis of ginsenoside Rh$_2$from 20(S)-protopanaxadiol obtained by alkaline hydrolysis of total ginsenoside. The regioselective synthesis of this compound was achieved by protection of 12-OH group.

• Journal of Photoscience
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• 제9권2호
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• pp.362-363
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• 2002

Since chlorophyll a and bacteriochlorophyll a are asymmetric molecules, an external ligand can coordinate to the central Mg atom either from the chiorin macrocycle side where the C13$^2$-methoxycarbonyl moiety protrudes (denoting as the 'back' side) or frome the other side (the 'face' side). We investigated which side of the macrocycle is favored for the ligand coordination, by survey of the highly resolved crystal structures of various photosynthetic proteins and theoretical model calculations. It is found that chlorophyll a as well as bacteriochlorophyll a and b in the photosynthetic proteins mostly bind their ligands on the 'back' sides. This finding was confirmed by the theoretical calculations for methyl chlorophyllide a and methyl bacteriochlorophyllide a as models: the 'back' type ligand-(bacterio )chlorophyll complex was more stable than the 'face' type one. The calculations predicted influence of the Cl3$^2$-stereochemistry on the choice of the side of the ligand coordination, which is discussed in relation to the presence of the Cl3$^2$-epimer of chlorophyll a in photosystem I reaction center [I].

• Journal of Photoscience
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• 제9권2호
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• pp.367-369
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• 2002

Chlorophyll (ChI) a' is the Cl3$^2$-epimer of ChI a which is the constituent of P700, the primary electron donor of Photosystem (PS) I, of a thrmophilic cyanobacterium, Synechococcus elongatus, whose structure was recently determined by X-ray crystallography. To determine whether PS I of diverse oxygenic photosynthetic organisms universally contain one molecule of ChI a ’, pigment compositions of thylakoid membranes and PS I complexes isolated from cyanobacteria, green algae, red algae and higher plants were determined by reversed-phase HPLC. The results show that involvement of one ChI a'molecule in PS I is the universal feature for Chi a-based PS I of oxygenic photosynthetic organisms.

• Journal of the Korean Wood Science and Technology
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• 제35권5호
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• pp.93-99
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• 2007

Paulownia coreana inner bark was collected, extracted in 70% acetone, concentrated under reduced pressure and sequentially fractionated using n-hexane, $CH_2Cl_2$, EtOAc and $H_2O$, then freeze dried to give brown powders. A portion of the EtOAc soluble powder was chromatographed on a Sephadex LH-20 column using a serious of aqueous methanol and ethanol-hexane mixture as eluting solvents. Two phenolic acid, $\rho$-courmaric acid and caffeic acid, two isomeric phenylethanoid glycosides, verbascoside and iso-verbascoside, and one epimeric phenylpropanoid glycoside, cistanoside F, were isolated and their structures were elucidated by spectroscopic analysis such as NMR and MS.

• BMB Reports
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• 제32권1호
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• pp.72-75
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• 1999

In an effort to understand the function of the eryBVII gene in the erythromycin biosynthetic gene cluster, we overexpressed the eryBVII gene in E. coli and TDP-6-deoxy-L-threo-D-glycero-4-hexulose was used as a substrate of the overexpressed EryBVII enzyme. The enzymatic reaction product was chemically modified by reduction and peracetylation. Structural analysis of the derivatized enzymatic products by GC-Mass Spectrophotometry indicated that TDP-6-deoxy-L-threo-D-glycero-4-hexulose could be converted into its epimer by EryBVII enzyme. Based on this result, TDP-6-deoxy-L-threo-D-glycero-4-hexulose was indeed the substrate of EryBVII enzyme and the function of the eryBVII gene was confirmed.

• 통합자연과학논문집
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• 제2권3호
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• pp.185-189
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• 2009

The new MPV-type reagent, Al-fluorodiisobutylalane (DIBAF), has been prepared and their reducing characteristics in the reduction of selected organic compounds containing representative functional groups have been examined in order to find out a new reducing system with unique applicability in organic synthesis. In general, the reagent is extremely mild, showing only reactivity toward aldehydes, ketones, and epoxides. The reagent achives a clean 1,2-reduction of enals to the corresponding allylic alcohols in a 100% purity, but shows no reactivity toward enones. The reagent also shows an excellent regioselective cleavage of substituted epoxides. In addition, DIBAF produces the thermodynamically more stable alcohol epimer in high stereoselectivity in the reduction of cyclic ketones.