• Natural Product Sciences
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• 제3권1호
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• pp.14-18
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• 1997

Two new diterpenoids, orientalin A (1), and B (2), have been isolated together with six known compounds, kirenol (3), $ent-16{\beta},17-dihydroxykauran-19-oic$ acid (4), $ent-16{\beta},17-dihydroxykauran-19-oic$ $acid-16{\beta},l7-acetonide$ (5), $3,7-dimethylquercetin$ (6), ${\beta}-sitosterol$ (7), and daucosterol (8) from the ethanol extract of Siegesbeckia orientalis (Compositae). Their chemical structures have been elucidated as $ent-15-acetoxy-2{\alpha},16,19-trihydroxypimar-8(14)-ene$ (1), $ent-16-acetoxy-2{\alpha},15,19-trihydroxypimar-8(14)-ene$ (2), respectively, on the basis of chemical and spectral evidence.

• Natural Product Sciences
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• 제8권1호
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• pp.26-29
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• 2002

The MeOH extract of Sorbus commixta (Rosaceae) exhibited strong DPPH radical scavenging activity, and through activity-guided fractionation two antioxidant compounds were isolated and identified as $catechin-7-O-{\beta}-D-xylopyranoside$ (1) and $catechin-7-O-\;{\beta}-D-apiofuranoside$ (2) by physicochemical and spectrometric methods. To evaluate the antioxidant effect of these compounds, some in vitro tests, such as the DPPH radical scavenging activity test, the superoxide radical scavenging activity test and the lipid peroxidation inhibitory activity test, were performed. Compounds 1 and 2 showed stronger activities than both a-tocopherol and butylated hydroxy anisole (BHA) in each assay.

• Natural Product Sciences
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• 제15권2호
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• pp.76-82
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• 2009

Phytochemical investigation of the EtOAc and n-BuOH fractions obtained from the crude methanol extract of the seeds of Butyrospermum parkii led to the isolation of seven compounds including 1${\beta}$,2${\alpha}$,3${\alpha}$-trihydroxyurs-12-en-28-oic acid (1${\beta}$-hydroxyeuscaphic acid) which full NMR assignment is herein reported for the first time. The above extract, fractions and some of the isolated compounds were screened for antimicrobial and antioxidant activities; 1${\beta}$-hydroxyeuscaphic acid was the more potent.

• 한국대기환경학회지
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• 제20권4호
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• pp.515-521
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• 2004

The catalytic oxidation of volatile organic compounds (methanol. acetaldehyde) has been characterized using the copper phthalocyanine catalyst in a fixed bed flow reactor under atmospheric pressure. The catalytic activity for pretreatment conditions was examined by this reaction system. The catalytic activity was ordered as follows: metal free-PC＜Cu ($\alpha$)-PC＜Cu ($\beta$)-PC The formaldehyde, carbon monoxide as a partial oxidation product of methanol and acetaldehyde over Cu ($\alpha$)-PC catalyst were detected and the conversions of methanol and acetaldehyde were accomplished above 95% over Cu ($\alpha$) -PC, Cu ($\beta$) - PC catalyst at 35$0^{\circ}C$. The pretreated metal free -PC, Cu($\alpha$)-PC, Cu($\beta$)-PC catalysts have been characterised by TGA, EA and XRD analysis. The catalytic activity pretreated with air and $CH_3$OH mixture (P-4) or air only (P-5) was very excellent. XRD and EA results showed that Cu($\alpha$)-PC, Cu($\beta$)-PC were destroyed an(1 new metal oxide such as CuO were formed.

• Bulletin of the Korean Chemical Society
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• 제34권1호
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• pp.121-127
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• 2013

New types of monocyclic ${\beta}$-lactams constitute an important class of compounds due to their unique structures and natures. Here, the design and synthesis of new 4-alkylthio monocyclic ${\beta}$-lactams 2a and 3a are reported. Significantly, compounds 2a and 3a, while keeping a monocyclic system, were designed to contain all of the substructures provided by the cleavage of C(2)-C(3) bond in penicillins. Efficient synthetic pathways for compounds 2a and 3a were established based on two different strategies. Compound 2a was synthesized from raw materials, using 4-acetoxyazetidin-2-one as a key intermediate, through a ten-step synthetic sequence in 3% overall yield. Compound 3a was synthesized from potassium salt of penicillin G (17), using the degraded product 20 as a key intermediate, through a six-step synthetic sequence in 11% overall yield. 4-Alkylthioazetidin-2-one derivatives, introduced in this study, could serve as valuable intermediates for the development of new monocyclic ${\beta}$-lactams.

• Natural Product Sciences
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• 제18권3호
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• pp.190-194
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• 2012

The effects of methanol extract of the leaves of Brassica juncea and its major component, isorhamnetin 3-O-${\beta}$-D-glucopyranoside on hepatic alcohol metabolizing enzymes were investigated. The methanol extract and isorhamnetin 3-O-${\beta}$-D-glucopyranoside supplementations increased the activities of microsomal ethanol oxidizing system and aldehyde dehydrogenase in a dose-dependent manner, and had mild effects on the activities of alcohol dehydrogenase and catalase. Isorhamnetin 3-O-${\beta}$-D-glucopyranoside alleviated the adverse effect of ethanol ingestion by enhancing the activities of alcohol oxidizing emzymes, microsomal ethanol oxidizing system and aldehyde dehydrogenase.

• Bulletin of the Korean Chemical Society
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• 제15권12호
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• pp.1064-1069
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• 1994

Chlorobis(isoprene)rhodium(Ⅰ) (3), prepared by olefin-exchange reaction of chlorobis(cyclooctene)rhodium dimer (2) with isoprene, reacted with benzaldimine 4 to give iminoacylrhodium(Ⅲ) ${\eta}^3$-1,2-dimethylallyl complex 6. Ligand-promoted reductive elimination of 6 by pyridine and P(OMe)$_3$ produced ${\beta},{\gamma}$-unsaturated ketimine 8, which was readily hydrolyzed to give ${\beta},{\gamma}$-unsaturated ketone 9. Other methyl branched dienes such as 2,3-dimethylbutadiene, 3-methyl-1,3-pentadiene, 2-methyl-1,3-pentadiene, 2,4-dimethyl-1,3-pentadiene, 3-methyl-1,4-pentadiene and 2-methyl-1,4-pentadiene, were applied the synthesis of ${\beta},{\gamma}$-unsaturated ketones. In case of 2,4-dimethyl-1,3-pentadiene, only ${\gamma},{\delta}$ -unsaturated ketone 25, 1,2-addition product, was obtained, may be due to the mono-olefin coordination.

• Bulletin of the Korean Chemical Society
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• 제5권6호
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• pp.215-218
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• 1984

A series of S-(2,2-diethoxycarbonyl-1-phenylethyl)-L-cysteine derivatives (10a-e) were synthesized from the reaction of $\beta$$\beta$-diethoxycarbonylstyrene with L-cysteine in 1:1 aqueous methanol. Thus, S-(2,2-diethoxycarbonyl-1-phenylethyl)-L-cysteine( 10a), S-[2,2-diethoxycarbonyl-1-(3',4'-methylendioxy)ph enylethyl]-L-cysteine (10b), S-[2,2-diethoxycarbonyl-1-(3',4',5'-trimethoxy)phe nylethyl]-L-cyseine (10c), S-[2,2-diethoxycarbonyl-1-(p-hydroxy)phenylethyl] -L-cysteine (10d), S-[2,2-diethoxycarbonyl-1-(p-methoxy)phenylethyl] -L-cysteine (10e) were obtained in moderate to excellent yields. The structure of the adducts was characterized by analytical and spectral data. The effects of pH upon the product yields were also briefly examined.

• Bulletin of the Korean Chemical Society
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• 제10권3호
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• pp.270-272
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• 1989

The polymeric species formed on the hydrolysis of Th(IV) from solubility experiments of $ThO_2$ in 0.1M $NaClO_4$ and $Th(OH)_4\;in\;0.5M\;NaClO_4$ were removed by ultrafiltration using 1 nm ultrafilters. The resultant equilibrium concentrations of mono-hydroxy Th(IV) species in solutions between pH 1.5 to 13 were measured by the NAA method. From these data solubility product of thorium dioxide and the stability constants of mono-hydroxy Th(Ⅳ) were determined. The values obtained were log $K_{sp}\;-\;50.76\;{\pm}\;0.08, log\;{\beta}_{1,1}\;12.42\;{\pm}\;0.02,\;log\;{\beta}_{1,2}\;22.46\;{\pm}\;0.15, log\;{\beta}_{1,3}\;34.36\;{\pm}\;0.07,\;log\;{\beta}_{1,4}\;42.58\;{\pm}\;0.08$, which are in good agreement with the values given in the literature. In addition, several dimeric species, $Th_2(OH)_2\;^{6+},\;Th_2(OH)_3\;^{5+} and\;Th_2(OH)_4\;^{4+}$ have been identified.

• Natural Product Sciences
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• 제6권4호
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• pp.199-200
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• 2000

A flavonol diglucoside was isolated from the leaves of Brassica juncea L. The structure of the compound was elucidated as isorhamnetin $3,7-di-O-{\beta}-D-glucopyranoside$ (1) on the basis of chemical and spectral evidence.