• Biomolecules & Therapeutics
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• v.17 no.4
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• pp.412-417
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• 2009

In the course of screening for antioxidant compounds by measuring the radical scavenging effect on DPPH (1,1-diphenyl- 2-picrylhydrazyl), a total extract of the twigs of Vitex rotundifolia (Verbenaceae) was found to show potent antioxidant activity. Subsequent activity-guided fractionation of the methanolic extract led to the isolation of three iridoid compounds, 10-O-vanilloylaucubin (1), 10-O-p-hydroxybenzoylaucubin (2) and aucubin (3), two C-glycoside flavones, vitexin (4) and orientin (5), and a quinic acid derivative, 3,4-di-O-caffeoylquinic acid (6). Their structures were elucidated by spectroscopic studies. Among them, compounds 5 and 6 showed the significant antioxidative effects on DPPH free radical scavenging test. In riboflavin-NBT-light and xanthine-NBT-xanthine oxidase systems, compounds 5 and 6 exhibited the formation of the blue formazan in a dose-dependent manner. Compounds 5 and 6 showed better superoxide quenching activities than vitamin C.

• Korean Journal of Pharmacognosy
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• v.18 no.2
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• pp.99-102
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• 1987

A new diterpene, mp $178{\sim}180^{\circ}$, $C_{21}H_{28}O_5$, was isolated from the root of Agastache rugosa O. Kuntze in the family of Labiatae. The structure of this compound was postulated as $19(4{\rightarrow}3)-abeo-12,14,15-trihydroxy-11-methoxy-abiet-4(18)$, 8,11,13-tetraen-7-one by spectroscopic methods.

• Journal of the Korean Magnetic Resonance Society
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• v.4 no.1
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• pp.1-11
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• 2000

Supported vanadium oxides are being used extensively as catalysts for a variety of reactions, including partial oxidations and ammoxidations. A series of vanadium oxide supported on TiO2-ZrO2 was obtained by impregnating ammonium metavanadate slowly into a mixed precipitateof Ti(OH)4-Zr(OH)4, followed by calcining in air at high temperatures. The prepared catalysts were characterized by 51V solid-state NMR. In the calcined catalysts 51V NMR studies indicated the peaks corresponding to distorted tetrahedral vanadia species at low V2O5 contents and octahedral vanadia species at high vanadia loadings. These results illustrate the suitability of 51V NMR as a unique quantitative spectroscopic tool in the structural analysis of vanadium(V) oxide catalytic materials.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.50.1-50.1
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• 2015

The origin of globular cluster (GC) color bimodality, which is one of the salient phenomena observed in most large galaxies, has not yet been fully resolved. The phenomenon has conventionally been interpreted as a bimodal metallicity distribution based on an assumption of linear GC color-metallicity relations (CMRs). Recent studies however suggest that nonlinear GC CMRs can cause a bimodal color distribution even from a single-peaked metallicity spread. Using photometric and spectroscopic data on GCs in NGC 5128 (Cen A) and NGC 4594 (Sombrero), we investigate the nonlinearity of GC CMRs and compare the observed GC CMRs with the predictions of stellar population simulation models. Our careful selection of old GCs effectively reduces the scatter and reveals the nonlinear nature of the GC CMRs for various colors. The overall shape of the observed CMRs agrees well with that of the modeled CMRs, while offsets are present for some colors. We discuss the implications of our results in terms of the GC color bimodality and GC formation in NGC 5128 and NGC 4594.

• Natural Product Sciences
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• v.14 no.3
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• pp.202-205
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• 2008

The antioxidant activity of Paeonia suffruticosa (Paeoniaceae) was determined by measuring the radical scavenging effect on DPPH (1,1-diphenyl-2-picrylhydrazyl). The methanolic extract of P. suffruticosa showed the strong antioxidant activity. The antioxidant activity of ethyl acetate soluble fraction was stronger than that of the others ($IC_{50}$, $1.2\;{\mu}g/mL$), and the fraction was subjected to purification by repeated silica gel and Sephadex LH-20 column chromatography. Suffruticosol A, suffruticosol B, methyl gallate, and gallic acid, were isolated from the ethyl acetate soluble fraction. Their structures were elucidated by physico-chemical and spectroscopic studies.

• Journal of Pharmaceutical Investigation
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• v.18 no.2
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• pp.49-53
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• 1988

Pivaloyloxymethyl ester of piperacillin was synthesized by reacting sodium piperacillin with chloromethyl pivalate, and its chemical structure was determined by infrared and $^1H$ nuclear magnetic resonance spectroscopic methods. The pharmaceutical properties of the ester were investigated to assess its potential as a novel prodrug of piperacillin. The interface transfer of piperacillin and the ester was studied in a two-phase in vitro system composed of aqueous pH buffers and n-octanol. The ester was more lipophilic, and less water soluble above pH 4.0 than piperacillin. Significant antibacterial activity was not observed in the ester in vitro, but the ester was hydrolyzed into the parent drug in the rat liver homogenate. The serum levels of orally administered ester suspension containing 0.1% Tween 80 were measured in rabbits. It was found that the ester showed higher blood level, comparing with no observation of piperacillin in serum, but the time reaching the maximum serum concentration was 5 hr.

• Journal of Photoscience
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• v.10 no.1
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• pp.165-173
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• 2003

m-Phenylene-linked biscarbenes, bisnitrenes and carbenonitrenes can be formed photochemically from appropriate nitrogenous precursors. Generation of such reactive intermediates under matrix-isolation conditions allows for their characterization by spectroscopic techniques such as ESR, UV /vis and IR. The latter method is also useful in characterizing secondary products derived from these reactive intermediates. Computational chemistry methods complement experimental IR data, aiding, thus, in identification of such compounds. In addition electronic structure calculations help in developing qualitative and semi-quantitative models, which can be useful in predicting ground-state multiplicities. The parent systems of m-phenylene-linked carbenes and nitrenes have high-spin ground states, but a switching to lower multiplicity can be achieved by chemical substitution. The ground state and various low-lying excited states of m-phenylenecarbenonitrenes can be reasonably approximated by simple valence-bond depictions. Finally, m-phenylenecarbenonitrenes are photoreactive in the inert matrix isomerizing to cyclopropene derivatives.

• Natural Product Sciences
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• v.21 no.1
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• pp.25-29
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• 2015

In a continuation of our studies to discover bioactive secondary metabolites from marine sources, we further investigated samples from a tryptamine and phenyl-alkane producing sponge, which resulted in the isolation of four uncommon small molecules and five nucleosides. Their structures were determined to be 7,8-dihydroimidazo[1,5-c]pyrimidin-5(6H)-one (1), 5-chlorocavernicolin (2), maleimide-5-oxime (3), 3-methylmaleimide-5-oxime (4), uridine (5), 2'-deoxyuridine (6), thymidine (7), adenine (8), and adenosine (9) by spectroscopic analyses. The isolated compounds were evaluated for inhibitory activity against soluble epoxide hydrolase (sEH) as well as the Wnt/${\beta}$-catenine signaling pathway.

• Korean Journal of Pharmacognosy
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• v.40 no.4
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• pp.334-338
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• 2009

Six iridoids were isolated from the 70% ethanol extract of Lonicera Caulis (Caprifoliaceae) and their structures were identified as epialyxialactone (1), secologanin dimethyl acetal (2), sweroside (3), loganin (4), loganic acid (5) and demethylsecologanol (6). The chemical structures of these compounds were identified on the basis of spectroscopic methods and comparison with literature values. This is the first report of the iridolactone, epialyxialactone (1), from the Caprifoliaceae plants and loganic acid (5) and demethylsecologanol (6) from Lonicera Caulis.

• Journal of Microbiology and Biotechnology
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• v.16 no.1
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• pp.109-117
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• 2006

The Rev binding to Rev Responsive Element (RRE) of HIV-1 mRNA plays an important role in the HIV-I viral replication cycle. The disruption of the Rev-RRE interaction has been studied extensively in order to develop a potential antiviral drug. In order to provide the basis for a more promising approach to develop a Rev-RRE binding inhibitor against HIV-I infection, it is necessary to understand the binding modes of the aminoglycoside antibiotics to RRE. In the present study, the binding mode of a modified antibiotic, a neamine conjugated with pyrene and arginine (NCPA), to RRE has been studied by the methods of $T_m$ measurement and spectroscopic analysis of RRE with or without antibiotics. The results confirmed that NCPA competes with Rev in binding to RRE.