• Korean Chemical Engineering Research
• /
• 제57권2호
• /
• pp.164-171
• /
• 2019

The protonation parameters, dissociation constants ($pK_{BH^+}$) of conjugate acid, slope values (m, ${\phi}$ and $m^*$) and correlation coefficients (r) of hydroxamic acids were determined by Hammett acidity function method, Bunnett-Olsen method and excess acidity method in hydrochloric and perchloric acid solutions. Effect of acid concentration on partition and percentage protonation was also studied. $pK_{BH^+}$ values show that hydroxamic acids do not behave as Hammett bases, but hydroxamic acids behave as weak bases in strong acidic solutions. The values of $pK_{BH^+}$ obtained through Bunnett-Olsen method and excess acidity method were compared with the Hammett acidity function. ChemAxon's MarvinSketch 6.1.5 software was also used for determining $pK_a$, pI and microspecies distribution (%) of hydroxamic acids with pH. Hydrogen donor and acceptor values and logD were also obtained. The results show that N-p-chlorophenyl-4-bromobenzohydroxamic acid has the highest $pK_a$ and lowest logD values. On the contrary, N-phenyl-3,5-dinitrobenzohydroxamic acid has lowest the $pK_a$ and highest logD values.

• 공업화학
• /
• 제30권3호
• /
• pp.313-315
• /
• 2019

정밀화학 및 화장품 산업에서 널리 사용되는 N-hydroxysuccinimide (NHS)의 새로운 실용적 합성법을 개발하였다. 기존 합성법은 무수 숙신산과 $NH_2OH$ 반응 후 강산을 촉매로 약 70%의 수율로 NHS를 얻는다. 이 방법은 무수 숙신산을 사용하여 비교적 쉽게 NHS를 얻을 수 있는 장점이 있으나 비싼 무수 숙신산을 사용하기 때문에 전혀 경제적이지 않다. 이런 단점을 극복하기 위해서 본 연구에서는 무수 숙신산 대신에 저렴한 숙신산과 Lewis 산인 Zinc acetate를 촉매로 사용하여 80%의 높은 수율로 NHS를 제조하는 새로운 경제적인 합성법을 개발하였으며 경제성 평가 결과 약 15%의 원가 절감 효과가 있음을 확인하였다.

• Biomolecules & Therapeutics
• /
• 제24권4호
• /
• pp.438-445
• /
• 2016

Cyperi Rhizoma (CR), the rhizome of Cyperus rotundus L., exhibits neuroprotective effects in in vitro and in vivo models of neuronal diseases. Nevertheless, no study has aimed at finding the neuroactive constituent(s) of CR. In this study, we identified active compounds in a CR extract (CRE) using bioactivity-guided fractionation. We first compared the anti-oxidative and neuroprotective activities of four fractions and the CRE total extract. Only the ethyl acetate (EA) fraction revealed strong activity, and further isolation from the bioactive EA fraction yielded nine constituents: scirpusin A (1), scirpusin B (2), luteolin (3), 6'-acetyl-3,6-diferuloylsucrose (4), 4',6' diacetyl-3,6-diferuloylsucrose (5), p-coumaric acid (6), ferulic acid (7), pinellic acid (8), and fulgidic acid (9). The activities of constituents 1-9 were assessed in terms of anti-oxidative, neuroprotective, anti-inflammatory, and anti-amyloid-${\beta}$ activities. Constituents 1, 2, and 3 exhibited strong activities; constituents 1 and 2 were characterized for the first time in this study. These results provide evidence for the value of CRE as a source of multi-functional neuroprotectants, and constituents 1 and 2 may represent new candidates for further development in therapeutic use against neurodegenerative diseases.

• The Plant Pathology Journal
• /
• 제24권3호
• /
• pp.322-327
• /
• 2008

Antifungal activities of natural substrances from Eucalyptus darlympleana, E. globules, E. gunnii and E. unigera were evaluated against postharvest pathogens of kiwifruits, Botrytis cinerea, Botryosphaeria dothidea, and Diaporthe actinidiae, to screen effective natural substances as an alternative to chemical fungicides. Methanol extract of the Eucalyptus trees showed strong antagonistic activity against the pathogenic fungi. Among them, E. unigera and E. darlympleana effectively inhibited mycelial growth of the pathogens. For chemical identification of the antifungal substances, the methanol extract of E. darlympleana leaves was successively partitioned with $CH_2Cl_2$, EtOAc, n-BuOH and $H_2O$. Among the fractions, $CH_2Cl_2$ and n-BuOH showed strong inhibitory activity of mycelial growth of the fungi. Five compounds were isolated from EtOAc and n-BuOH fractions subjected to $SiO_2$ column chromatography. Two phenolic compounds(gallic acid and 3,4-dihydroxybenzoic acid) and three flavonoid compounds(quercetin, quercetin-3-O-$\alpha$-L-rhamnoside, quercetin-3-O-$\beta$-glucoside) were identified by $^1H$-NMR and $^{13}C$-NMR spectroscopy. Among them, only gallic acid was found to be effective in mycelial growth and spore germination of B. cinerea at relatively high concentrations. The results suggest that gallic acid can be a safer and more acceptable alternative to current synthetic fungicides controlling soft rot decay of kiwifruit during postharvest storage.

• 한국식품영양과학회지
• /
• 제29권5호
• /
• pp.814-821
• /
• 2000

나박김치의 저장성 향상을 위한 천연보존제로서 이용 가능성을 검토하기 위해 오미자 물추출물을 제조하여 이들 시료의 농도를 0.5, 1.0, 1.5, 2.0%로 사용하여 항산화력 및 전자공여능을 측정하고 나박김치 발효에 관여하는 젖산균에 대해 항균활성을 조사하였다. 항산호력은 TBA값을 측정하였는데, 오미자 물추출물의 농도가 높을수록 항산화 효과가 뚜렷이 나타났고, 시간이 경과할수록 그 효과는 현저하였다. 전자공여능 또한 오미자 물추출물의 농도가 높을수록 높은 전자공여능을 나타냈고, 1.0% 이상이 높은 전자공여능을 보였다. 나박김치에서 잦산균을 분리한 결과 117균주를 1차 분리하였고, 이 가운데 성장이 우수하고 산 생성력이 강한 4균주를 2차 선별하여 Lactobacillus brevis, Lactococcus faecalis, Leuconostoc mesenteroides, Lactobacillus plantarum을 확인하였다. 이들의 항균활성을 측정한 결과 Lactobacillus brevis를 제외한 세 균주 모두 오미자 물추출물 첨가에 의한 뚜렷한 성장 억제현상을 나타내었다. 따라서 나막김치 담금시에 항산화성과 항균활성이 있는 오미자 물추출물을 이용할 수 있는 가능성이 높을 것으로 생각되었다.

• Archives of Pharmacal Research
• /
• 제20권2호
• /
• pp.197-199
• /
• 1997

In conclusion, benzotriazole analogs prepared in this research showed strong possibility to be photochemically activated DNA cleaving agents. Electrophilic groups such as haloacetoxy groups on the alkyl chain of benzotriazole analogs promote the DNA cleaving ability. Synthesis of 1-(2-Naphthoyl) Benzotriazoles.

• KSBB Journal
• /
• 제10권3호
• /
• pp.264-270
• /
• 1995

Trigonopsis variabilis는 버l타락탐 항생제인 cephalosporin C (ceph C)를 ${\alpha}$-keto-adipyl-7 a aminocephalosporanic acid(AKA-7 ACA)로 생변 환하는 강력한 D-amino acid oxidase 효소를 갖고 있다. 본 연구는 이 D-AAO 효소의 유전자를 추출하기 위하여 polymerase chain reaction (PCR)을 사용하였다. PCR 단편을 콜로닝하기 위하여 Taq D DNA polymerase, Klenow, T4 DNA polymerase I, Alkaline phosphatase Calf Intestinal와 T4 kinase 의 효소반응을 이용하여 4가지의 방법을 샤용한 결 과, blunt - end 의 PCR fragment 를 phosphory­l lation하고 blunt -end의 pUC18 plasmid를 dephos phorylation 한 후 ligation 한 것 이 가장 좋은 클로 닝 효율을 보였다. Ceph C에 대한 D-AAO 효소의 활성은 재조합 E. coli의 세포추출액과 permea bilized cells에서 모두 확인할 수 있었다.

• KSBB Journal
• /
• 제32권3호
• /
• pp.199-205
• /
• 2017

The aim of this study was to investigate probiotic characteristics and fermentation profile of selected lactic acid bacteria (LAB) isolated from traditional fermented foods. Antibacterial activity against various pathogens, acid and bile salt tolerance, cell hydrophobicity, and antibiotic resistance were examined. 16S rRNA sequencing was carried out to identify eight presumptive LAB isolates. In general, all identified LAB (Enterococcus faecium MG89-2, Lactobacillus plantarum MG207, L. paracasei MG310, L. casei MG311, Streptococcus thermophilus MG510, L. bulgaricus MG515, L. helveticus MG585, and L. fermentum MG590) showed strong antimicrobial activity. Also, the selected strains were resistant to bile acid up to 3% and their autoaggregation rates were as high as 60%. All selected strains tested were sensitive to chloramphenicol, tetracycline, and ampicillin, whereas resistant to nalidixic acid and kanamycin.

• 한국응용곤충학회지
• /
• 제34권2호
• /
• pp.95-99
• /
• 1995

무당벌레(Harmonia axyridis)의 중장 내에서 먹이 단백질이 소화되는 과정을 연구하기 위하여 진딧물과 생간의 AP를 모델 단백질로 이용하였다. 천역 먹이인 긴꼬리볼록진딧물(Megoura crassicauda)과 인공먹이인 닭의 생간은 각각 고유의 acid phosphatase(AP)를 가지고 있으며, 무당벌레의 중장 내부로 들어온 후에도 활성을 나타내었다. 무당벌레의 장에서 자체적으로 생성하여 중장 내부로 분비하는 AP는 관찰되지 않았다. 무당벌레의 단백질 소화력은 먹이의 종류에 따라 차이를 나타내는 경향을 보였다. 생간의 AP는 무당벌레 중장내에서 12시간이 지나면 거의 활성을 잃어 버리나 긴꼬리볼록 진딧물의 AP는 24시간이 경과하여도 강한 활성을 나타내었다.

• 한국식품영양학회지
• /
• 제5권2호
• /
• pp.69-76
• /
• 1992

Sogokju, an old Korean rice wine, was brewed in laboratory scale in February, 1978, and the changes in chemical component and microorganisms in wine mash were investigated during brewing. In the course of first-mash brewing, lactic acid bacteria became the most predominant microflora in 3 days of fermentation lowering the pH of mash to 4.2. But at 7 days, the most predominant microorganism was changed from lactic acid bacteria to least, pH reached 3.6, and the saccharogenic activity of mash was reduced from initial 10 to 3.6. During second-mash brewing, remarkable changes did not occurred in pH and acidity, maintaining 3.5∼3.7 of pH and 8.0∼8.8 of acidity. Ethanol fermentation was proceeded vigorously until 20 days of fermentation, but it reached stationary state with 18.5% ethanol after 40 days, leaving reducing sugar unfermented in mash. Even if saccharogenic activity continued all during fermentation, it was thought to be too weak. The final product of Sogokju filterate, fermented for 60 day, contained 18.8% ethanol, 5.0% reducing sugar,0.4:1 total acid, 0.057% volatile acid, 0.206% amino acid and 7.3% extract. In sensory test, Sogokju scored good marks with similar level to commercial Bupju or Chungju. It had pale yellow color, gentle Nuluk-flavor and acid taste just a little strong.