• 공업화학
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• 제22권3호
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• pp.319-322
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• 2011

탈수제로 폭 넓게 사용되는 디사이클로헥실카르보디이미드(DCC)는 반응 후에 디사이클로헥실우레아(DCU)로 변환된다. 본 논문에서는 ${\beta}$-시토스테롤의 수용성 치환체의 합성에 사용되고 부산물로 나오는 DCU를 회수하여 정제한 후에, DCC로 변환시키는 반응을 연구하였다. 토실클로라이드(tosyl chloride, p-tolenesulfonyl chloride, TsCl)와 트리에틸아민(TEA)의 존재 하에서 DCU가 DCC로 변환되는 것을 확인할 수 있었으며, DCU 대비 1.5 당량의 TsCl 및 3.0 당량의 TEA를 사용하였을 때가 최적 반응 조건으로 나타났다. 반응물을 용매를 이용한 정제 과정을 거쳐 최종적으로 승화에 의해서 46%의 수율로 순수한 DCC를 회수할 수 있었다. 합성한 DCC의 화학 구조는 GC/MS, FT-IR 및 $^{13}C-NMR$에 의해서 확인하였다.

• The Korean Journal of Physiology
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• 제28권2호
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• pp.225-231
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• 1994

The present study was undertaken to investigate the role of endogenous nitric oxide in renin release under different physiological conditions. In the first series of experiments, renin release was either inhibited by acute volume-expansion (VE) or stimulated by clipping one renal artery in the rat. VE was induced by intravenous infusion of saline (0.9% NaCl) up to 5% of the body weight over 45 min under thiopental (50 mg/kg, IP) anesthesia. VE caused a decrease of plasma renin concentration (PRC). With $N^G-nitro-L-arginine$ methyl ester $(L-NAME,\;5\;{\mu}g/kg\;per\;min)$ superadded to VE, PRC decreased further. The magnitude of increase in plasma atrial natriuretic peptide levels following VE was not affected by the L-NAME. In two-kidney, one clip rats, L-NAME-supplementation resulted in a decrease, and L-arginine-supplementation an increase of PRC. Plasma atrial natriuretic peptide levels were significantly lower in the L-arginine group than in the control. Blood pressure did not differ among the L-NAME, L-arginine, and control groups. In another series of experiments, the renin response to a blockade of NO synthesis was examined using in vitro preparations from isolated renal cortex. L-NAME significantly increased basal renin release, although it was without effect on the isoproterenol-stimulated release. These findings suggest that endogenous nitric oxide significantly contributes to the renin release. Since many factors may affect the renin release in vivo, an interaction between NO and renin under various pathophysiological states is to be further defined.

• 한국산학기술학회논문지
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• 제14권2호
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• pp.977-982
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• 2013

다양한 종류의 지방산 아실 체인으로 치환된 Cellulose mixed esters(CME)는 재생 가능한 bio-based 폴리머이다. 셀룰로오스 에스터는 생분해성 고분자로써, 분해되지 않는 석유계 플라스틱을 대체할 미래 고분자 소재이다. 본 연구에서는 개질 실험에 앞서 alpha 셀룰로오스를 $40^{\circ}C$의 증류수에 2시간동안 activation하였다. Water-activated 셀룰로오스와, 다양한 불포화 지방산, 무수 아세트산을 $120^{\circ}C$의 lithium chloride/N,N-dimethylacetamide (LiCl/DMAc)용매에서 5시간동안 반응시켜 CME를 합성했다. 세척과 감압을 반복한 후, TGA, FT-IR, 1H-NMR과 FE-SEM를 통해 특성을 관찰하였고, water activation이 셀룰로오스의 수산기 치환에 미치는 영향에 대하여 조사하였다.

• Archives of Pharmacal Research
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• 제26권4호
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• pp.258-263
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• 2003

Colon-specific delivery of glucocorticoids is highly desirable for the efficient treatment of inflammatory bowel disease. We synthesized prednisolone 21-sulfate sodium (PDS) as a colon-specific prodrug of prednisolone (PD) and investigated its properties using rats as test animals. We expected that introduction of sulfate ester as a sodium salt might increase the hydrophilicity and restrict the absorption in the GI tract. If PDS is stable and nonabsorbable in the upper intestine, it will be delivered to the colon as an intact form, where it hydrolyze by the sulfatase to release PD. Compared with PD, the solubility of PDS increased and the apparent partition coefficient decreased greatly. PDS was stable on incubation with pH 1.2 and 6.8 buffer solutions and with the contents of the stomach and small intestine. On incubation with the cecal contents, PDS decreased to 9.6％ of the dose in 10 h producing PD. The amount of PD increased to give a maximum 54％ of the dose and decreased. As a control, when PD was incubated with the cecal contents, it decreased to 29％ of the dose in 8 h, which implied that reduction of PD proceeded under such conditions. These results suggested that hydrolysis of PDS took place to produce and accumulate PD, which decreased by reduction as the incubation period extended. Our results suggested that PDS can be a promising colon-specific prodrug of PD, and sulfate ester group might serve as a potential colon-specific promoiety, especially for the drugs which are resistant to reduction in the colon.

• 공업화학
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• 제24권3호
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• pp.231-238
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• 2013

본 연구에서 제조한 나노구형체 $TiO_2$는 자외선 차단 효과가 우수하면서도 노폐물 흡착을 하는 기능을 부여하기 위해 Sol-gel 방법으로 합성하였다. 다공성의 특성으로 높은 표면적에 의한 우수한 자외선 차단효과 및 흡착능력을 얻기 위해 pH를 조절하였다. 염기 처리한 $TiO_2$의 경우 가장 우수한 특성을 나타내었다. TGA로 글리세린을 흡착한 결과 1.16 mg의 높은 흡착 결과를 얻을 수 있었다. 또한 UV-A 영역에서 높은 반사율을 가지는 것을 확인하였다. 무기분체의 최적의 분산제를 찾기 위해 ester oil과 silicon oil를 사용하여 입도크기를 측정하였으며 180 nm정도의 입자로 약 6개월간 유지되었다. 이 결과를 통해, UV-A영역에서 우수한 능력을 가진 자외선 차단제로서 노폐물 흡착능력을 가진 $TiO_2$를 제조했으며 이로 인한 다양한 응용이 가능할 것으로 기대된다.

• KSBB Journal
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• 제11권5호
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• pp.529-535
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• 1996

효소적으로 합성된 메틸프룩토시드(methyl fruc­t to side )와 당의 혼합물로부터 Amberlite IRA -900 을 고정상 담체로 하여 당과 배당체를 액체 크로마 토그래피법으로 정밀 분리함으로써 메틸프룩토시드 를 출발물질로 하는 새로운 sugar ester의 합성 공 정이 연구개발되도록 하고, 액체 크로마토그래피법 에 의한 알킬배당체의 정밀 분리기술이 실용화될 수 있도록 최적조업조건과 해상도 빛 생산성을 검토하였다. Amberlite IRA-900을 고정상 담체로 한 메틸프 룩토시드의 정밀분리공정은 이론단수의 개념에 근거 한 선형 크로마토그래피 모델로 모사할 수 있었으며 에틸프룩토시드와 자당의 용출 크로마토그램을 잘 예측할 수 있었다. 급액농도가 각각 3g/L와 5g/L 인 메틸프룩토시드와 자당의 수용액으로부터 메틸프 룩토시드를 정밀분리하기 위해서는 급액을 $60^{\circ}C$에서 충전체적의 75%까지 주입하고공탑유속 1.13cm/mm의 중류수로 용출시킬 때 해상도 1.1에서 95% 이상의 회수율과 7mg MF/g-resin/h의 생산성을 얻었다.

• 폴리머
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• 제30권2호
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• pp.162-167
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• 2006

1,2,3,4-시클로부탄 테트라카복시산 이무수물과 4,4'-디아미노디페닐에테르(DDE)를 용액 중합 반응하여 폴리암산(PAA) 용액을 제조한 후, 1,2-에폭시-3-페녹시프로판과 반응시켜 폴리암산에스테르(PAE)를 합성하였다. 여기에 용해억제재로서 30 wt%의 디아조나프토퀴논 유도체(DI)를 첨가하였다. $365{\sim}400nm$의 파장에서 $200mJ/cm^2$의 자외광을 조사한 후, 0.95 wt%의 테트라메틸암모니움히드록사이드 수용액으로 현상한 결과 $25{\mu}m$ 해상도의 양성형 미세 화상을 얻었다. 비노광부에 잔존하는 폴리이미드 박막은 400nm에서 92% 이상의 우수한 광투과도를 나타내었다.

• 약학회지
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• 제40권3호
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• pp.279-292
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• 1996

To assess their stability as a prodrug of 5-fluorouracil (5-FU), four N-acyloxycarbonyl derivatives (1-(N-tert-butyloxycarbonyl)glycyloxymethyl-5-FU :BGFU, 1-(N-tert-butyloxycar bonyl)-leucyloxymethyl-5-FU:BLFU, 1-(N-tert-carbobenzyloxymethyl) glycyloxymethyl-5-FU:CGFU and 1-(N-tert-carbobenzlyoxymethyl)leucyloxymethyl-5-FU:CLFU) possessing differently protected amino acids, and two acetic acid derivatives (5FU-1-acetylpentane:FUAP and 5-FU-1-acetylhexane:FUAH) were synthesized and their physicochemical properties, hydrolysis kinetics, acute toxicity and antitumor activity were evaluated. The lipid-water partition coefficients of six 5-FU prodrugs were higher than that of 5-FU and their aqueous solubilities were in the following rank order; BGFU>FUAP>CGFU>BLFU>CLFU${\simeq}$FUAH. The hydrolysis of N-acyloxycarboyl derivatives, greater at higher pH, was enhanced in presence of liver homogenate or human plasma. Meanwhile, acetic acid ester derivatives, very stable, were hydrolyzed by liver homogenate. Absorption rate constants were 0.181, 0.121, 0.111, 0.168, 0.168, 0.116 and 0.125 $hr^{-1}$ for 5-FU, BGFU, BLFU, CGFU, CLFU, FUAP and FUAH, respectively. The cytotoxicity of N-acyloxycarbonyl derivatives was 4 to 5 times lower than that of 5-FU, but that of acetic acid ester derivatives was negligeble. The $LD_{50}$ values were 204, 325.97 (133.59, amount as 5-FU), 708.16 (262.13), 663.50 (211.77), 382.33 (192.54) and 272.33 (130.09) mg/kg for 5-FU, BGFU, CGFU, CLFU, FUAP and FUAH, respectively. While N-acyloxycarbonyl derivatives showed enhanced antitumor activity and therapeutic ratio (3.30, 3.06, 4.19, 3.11 and 1.81 for BGFU, BLFU, CGFU, CLFU and 5-FU, respectively), FUAH and FUAP showed a smaller therapeutic ratio (0.79 and 0.83).

• Tribology and Lubricants
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• 제31권6호
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• pp.258-263
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• 2015

Biodiesel is an environmentally-friendly fuel with low smoke emission because it contains about 10% oxygen. Biodiesel fuel prepared by transesterification of vegetable oil or animal fats is susceptible to auto-oxidation. The rate of auto-oxidation depends on the number of methylene double bonds contained within the fatty acid methyl or ethyl ester groups. Biodiesel may be easily oxidized under several conditions, i.e., upon exposure to sunlight, temperature, oxygen environment. Maintenance of the fuel quality of biodiesel requires the development of technologies to increase the resistance of biodiesel to oxidation. Treatment with antioxidants is a promising approach for extending the shelf-life or storage time of biodiesel. The chemical properties of various amine-based antioxidants were evaluated after synthesis of the antioxidants by condensation of phenylenediamine with alkylamines at room temperature. In general, the oxidative stability can be assessed based on various experimental parameters. Such parameters may include temperature, pressure, and the flow rate of air through the samples. The Rancimat method (EN14112) was selected because it is a rapid technique that requires very little sample and provides good precision for oxidative degradation analysis. Specifically, the EN 14112 technique provides enhanced efficiency for oxidative stability evaluation when a larger ester head group is utilized. Therefore, this technique was employed for evaluation of the oxidation stability of biodiesel by the Rancimat method (EN14112).

• 대한화장품학회지
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• 제28권1호
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• pp.135-149
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• 2002

To date, research on the regulation of melanogenesis has focused on factors which affect tyrosinase, the rate-limiting enzyme in the melanogenic pathway, by searching for chemicals which competitively inhibit tyrosinase function. Many types of tyrosinase inhibitors have been developed, but no satisfactory results have been made clinically until now, To find a new whitening agent, which effectively inhibits melanogenesis, we synthesized several compounds and selected compounds by cell-based assay system. Finally, 3, 4, 5-trimethoxy cinnamaie thymol ester(TCTE, Melasolv) was selected and the effects of TCTE on melanogenesis were investigated. Treatment of mouse-derived melanocyte melan-a cells with TCTE results in a marked down-regulation of tyrosinase activity. 80% decrease of tyrosinase activity occurs with 30uM TCTE treatment for 72 hours without affecting cell growth. The inhibition of tyrosinase activity is dose-dependent and melanin content was also decreased to 40%. From the in vitro tyrosinase assay using cell extract, TCTE does not act as a direct inhibitor of the enzyme. Treatment of melan-a cultures with TCTE blocks the increase in tyrosinase activity by either forskolin, 3-isobutyl-1-methtyl-xanthine. TCTE decreased the expression of tyrosinase, TRP-1 without effects on TRP-2 protein expression through the down regulation of tyrosinase and TRP-1 mRNA. From the results of cAMP immunoassays, intracellular levels of the cyclin nucleotide are unaffected in cells treated with TCTE. The inhibitory effects of melanin synthesis were also shown in reconstitute human epidermis model by topical application. These findings suggest that TCTE can be used for studying the regulation of melanogenesis and depigmenting agent.