• Electronics and Telecommunications Trends
• /
• v.14 no.6 s.60
• /
• pp.150-161
• /
• 1999

본 고에서는 국제표준화 기관인 ITU-T에서 진행하고 있는 B-ISDN의 일반적인 망 측면을 다루고 있는 Study Group 13의 표준화 활동에 대하여 주요 기술현황을 설명한다.

• YAKHAK HOEJI
• /
• v.41 no.1
• /
• pp.7-13
• /
• 1997

A regiospecific total synthesis on the precursor(18b) of rhodomycinones is described. The anion of 3-carbomethoxy-1(3H)-isobenzofuranone(13) was respectively condensed wi th naphthalenone (12) and butenoate(8) derivatives which were, prepared by two different synthetic routes to afford 9-ethyl-6,7-dihydroxy 7,8,9,10-tetrahydronaphthacene-5,12 dione(18b) after oxidation and reduction.

• KSBB Journal
• /
• v.8 no.1
• /
• pp.75-82
• /
• 1993

The inhibitory effect of cacao bean husk (CBH) extract on glucosyltransferase(GTasc) from Streptococcus mutans B13 was investigated. Water solube extract from CBH showeda sarong inhibitory effect (88-89%) on GTase from Streptococcus mutans Bl3. GTase inhibitors from sequential extraction by hot water or water-methanol had the strongest inhibition. Sources, fermentation, and types of solvents and fumigation processes did not influence the effect. These active compounds proved to be polyphones through acid hydrolytic analysis of the precipitates by ammonium sulfate or ethanol and proteinase K. It was also confirmed by additional column chromatography of Sephadex G-50, Sephadex LH-20 and DEAE-Sephdex A-50.

• Bulletin of the Korean Chemical Society
• /
• v.17 no.4
• /
• pp.314-321
• /
• 1996

Isoxazolidine derivatives 7 and 8 were synthesized from N-benzyl-C-(2-benzyloxyethyl)nitrones by 1,3-dipolar cycloaddition with ethyl crotonate. The isoxazolidine derivatives were converted to β-amino acid esters 9a and 9b by reduction with zinc in acetic acid. The β-amino acid esters were reacted with methylmagnesium bromide to give the 2-azetidinones (13a, 13b). The benzyl group of 2-azetidinones were removed by Birch reduction. The products were oxidized with PDC to give 3-[1-(t-butyldimethylsilyloxy)ethyl]-4-carboxymethyl-2-azetidinone derivatives (2a, 2c).

• Journal of Species Research
• /
• v.13 no.2
• /
• pp.131-135
• /
• 2024

Two unrecorded species, Brachynervus beijingensis and B. confusus are described from South Korea for the first time. A taxonomic study of the South Korean Brachynervus was initiated by Uchida (1955). Until now only one species, B. tsunekii, has been recorded from South Korea. In the study, we provide the diagnoses and photos of two unrecorded species of Brachynervus.

• Bulletin of the Korean Chemical Society
• /
• v.16 no.10
• /
• pp.994-997
• /
• 1995

• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.13
• /
• pp.5371-5376
• /
• 2015

Berberine (B1), isolated from stems of Coscinium fenestratum (Goetgh.) Colebr, was used as a principle structure to synthesize three phenolic derivatives: berberrubine (B2) with a single phenolic group, berberrubine chloride (B3) as a chloride counter ion derivative, and 2,3,9,10-tetra-hydroxyberberine chloride (B4) with four phenolic groups, to investigate their direct and indirect antioxidant activities. For DPPH assay, compounds B4, B3, and B2 showed good direct antioxidant activity ($IC_{50}$ values=$10.7{\pm}1.76$, $55.2{\pm}2.24$, and $87.4{\pm}6.65{\mu}M$, respectively) whereas the $IC_{50}$ value of berberine was higher than $500{\mu}M$. Moreover, compound B4 exhibited a better DPPH scavenging activity than BHT as a standard antioxidant ($IC_{50}=72.7{\pm}7.22{\mu}M$) due to the ortho position of hydroxyl groups and its capacity to undergo intramolecular hydrogen bonding. For cytotoxicity assay against human fibrosarcoma cells (HT1080) using MTT reagent, the sequence of $IC_{50}$ value at 7-day treatment stated that B1 < B4 < B2 ($0.44{\pm}0.03$, $2.88{\pm}0.23$, and $6.05{\pm}0.64{\mu}M$, respectively). Berberine derivatives, B2 and B4, showed approximately the same level of CAT expression and significant up-regulation of SOD expression in a dose-dependent manner compared to berberine treatment for 7-day exposure using reverse transcription-polymerase chain reaction (RT-PCR) assays. Our findings show a better direct-antioxidant activity of the derivatives containing phenolic groups than berberine in a cell-free system. For cell-based system, berberine was able to exert better cytotoxic activity than its derivatives. Berberine derivatives containing a single and four phenolic groups showed improved up-regulation of SOD gene expression. Cytotoxic action might not be the main effect of berberine derivatives. Other pharmacological targets of these derivatives should be further investigated to confirm the medical benefit of phenolic groups introduced into the berberine molecule.

• Korean Journal of Food Science and Technology
• /
• v.51 no.3
• /
• pp.295-299
• /
• 2019

We developed and validated species-specific primers for Branchiostegus japonicus and Branchiostegus albus to prevent the sale of B. albus as B. japonicus. Primers for B. japonicus and B. albus were designed against the cytochrome b gene. Multiplex PCR showed a 288 bp amplicon for B. japonicus, a 159 bp amplicon for B. albus, and a 502 bp amplicon for the internal control. The PCR product bands for B. japonicus, B. albus, and the internal control were present at 1 ng each. The specificity and sensitivity of the primers developed in this study were validated by testing 38 B. japonicus strains and 13 B. albus strains. Using this monitoring method, fake fish did not appear due to the agreement between the experimental results and the species. Therefore, the developed multiplex PCR method was suitable for differentiating B. japonicus and B. albus.

• Journal of Dairy Science and Biotechnology
• /
• v.13 no.1
• /
• pp.13-26.4
• /
• 1995

• Proceedings of the Korea Crystallographic Association Conference
• /
• 2002.05a
• /
• pp.13-13
• /
• 2002