• Journal of Microbiology and Biotechnology
• /
• 제26권3호
• /
• pp.441-451
• /
• 2016

Squalene is a linear triterpene formed via the MVA or MEP biosynthetic pathway and is widely distributed in bacteria, fungi, algae, plants, and animals. Metabolically, squalene is used not only as a precursor in the synthesis of complex secondary metabolites such as sterols, hormones, and vitamins, but also as a carbon source in aerobic and anaerobic fermentation in microorganisms. Owing to the increasing roles of squalene as an antioxidant, anticancer, and anti-inflammatory agent, the demand for this chemical is highly urgent. As a result, with the exception of traditional methods of the isolation of squalene from animals (shark liver oil) and plants, biotechnological methods using microorganisms as producers have afforded increased yield and productivity, but a reduction in progress. In this paper, we first review the biosynthetic routes of squalene and its typical derivatives, particularly the squalene synthase route. Second, typical biotechnological methods for the enhanced production of squalene using microbial cell factories are summarized and classified. Finally, the outline and discussion of the novel trend in the production of squalene with several updated events to 2015 are presented.

• 한국자기학회:학술대회 개요집
• /
• 한국자기학회 2017년도 임시총회 및 하계학술연구발표회
• /
• pp.165-166
• /
• 2017

• Bulletin of the Korean Chemical Society
• /
• 제30권12호
• /
• pp.2959-2961
• /
• 2009

Total synthesis of (${\pm}$)-licochalcone E (1), an allyl retrochalcone isolated from roots of Glycyrrhiza inflata, has been achieved from 4-tetrahydropyranyloxyacetophenone (7) with (E)-2-methoxy-4-(2-methyl-2-butenyloxy)benzaldehyde (6) or (Z)-2-methoxy-4-(2-methyl-2-butenyloxy)-benzaldehyde (11) through a convergent strategy involving aldol condensation and Claisen rearrangement as key steps.

• Bulletin of the Korean Chemical Society
• /
• 제22권7호
• /
• pp.699-702
• /
• 2001

A series of cleft-type ionophores having two convergent hydroxamic acid functions are prepared and their selective ionophoric properties toward heavy metal and transition metal ions have been investigated. Hydroxamic acids 3 exhibited a prominent selectivity toward heavy metal ions of Hg2+ and Pb2+, and transition metal ions of Cu2+ over other transition metal and alkaline earth metal ions from slightly acidic source phase (pH 6) to an acidic receiving phase (pH 1). Selective ionophoric properties toward Pb2+ and Cu2+ ions over other surveyed metal ions are also confirmed by the FAB-MS measurements.

• Bulletin of the Korean Chemical Society
• /
• 제18권5호
• /
• pp.519-522
• /
• 1997

A series of new ligands having convergent dicarboxylic acid functions, based-upon Rebek's cleft-type ionophore, have been prepared and their ion binding properties were investigated by the competitive extraction and transport experiments. The main purpose of the modification was to increase the lipophilicity of the Rebek's ionophore, which was attempted by utilizing propyl analog of Kemp's triacid or by changing the bridging unit. Ionophores 5 and 6 were found to have a pronounced ion-binding property toward Ca2+ ion. The selectivity in competitive extraction of ionophore 5 at pH 9 for Ca2+ over Mg2+ and Sr2+ is 2.0 and 59.3, respectively. The selectivity in competitive transport of ionophore 5 for Ca2+ over Mg2+ and Sr2+ is 29.8 and 99.3, and that of ionophore 6 is 10.0 and 23.2, respectively.

• Bulletin of the Korean Chemical Society
• /
• 제25권10호
• /
• pp.1581-1584
• /
• 2004

• 공업화학
• /
• 제17권6호
• /
• pp.633-637
• /
• 2006

본 연구에서는 triazole계 항진균제인 이트라코나졸의 대량합성을 위한 효과적인 합성법을 제시하였다. Janssen Pharmaceutica에 의해 발표된 기존의 의약화학적 합성경로는 2,4-dichloroacetophenone을 출발물질로 하는 직렬(linear) 합성의 14 단계로서 전체수율이 1.4%에 불과하였고 대량합성에 부적합한 위험물질로서 methanesulfonyl chloride ($CH_{3}SO_{2}Cl$)와 수소기체 및 sodium hydride (NaH)를 사용하고 있다. 또한 고가의 1-acetyl-4-(4-hydroxyphenyl)piperazine 및 팔라듐을 사용함으로써 생산 단가가 높은 문제점이 있었다. 이를 개선하기 위해서 병렬(convergent) 합성 전략을 수립하였는데, 이트라코나졸의 대략 반에 해당하는 중간체 II와 III을 각각 합성한 다음 두 부분을 결합시키는 12단계의 합성공정을 개발하였고 전체 수율은 12.0%로서 합성효율이 크게 개선되었다. 이 과정에서 공정을 간략화하고 위험물질 및 고가의 반응물의 사용을 배제함으로써 생산 원가를 크게 절감시킬 수 있었다.

• 한국통신학회논문지
• /
• 제21권3호
• /
• pp.612-621
• /
• 1996

In this paper, we propose the low sidelobe digital FIR doppler filter bank synthesis algorithm through the Gradient Descent method and it can be practially appliable to coherent pulse doppler radar signal processing. This algorithm shows the appropriate calculation of tap coefficients or zeros for FIR transversal fiter which has been employed in radar signal processor. The span of the filters in the filter bank be selected at the desired position the designer want to locate, and the lower sidelobe level that has equal ripple property is achieved than one for which the conventional weithtedwindow is used. Especially, when we implemented filter zeros as design parameters it is possible to make null filter gain at zero frequency intensionally that would be very efficient for the eliminatio of ground clutter. For the example of 10 tap filter synthesis, when filter coefficients or zeros are selected as design parameters the corresponding sidelobelevel is reducedto -70db or -100db respectively and it has good convergent characteristics to the desired sidelobe reference value. The accuracy ofapproach to the reference value and the speed of convergence that show the performance measure of this algorithm are tuned out with some superiority and the fact that the bandwidth of filter appears small with respect to one which is made by conventional weighted window method is convinced. Since the filter which is synthesized by this algorithm can remove the clutter without loss of target signal it strongly contributes performance improvement with which detection capability would be concerned.

• Macromolecular Research
• /
• 제17권7호
• /
• pp.499-505
• /
• 2009

General, fast, and efficient stitching methods are presented for the synthesis of Fr$\acute{e}$chet-type dendrimers with linear units at a core, as a preliminary investigation for the synthesis of dendritic-linear-dendritic materials. The synthetic strategy involved an inexpensive, 1,3-dipolar, cycloaddition reaction between an alkyne and an azide in the presence of the Cu(I) species, which is known as the best example of click chemistry. The linear core building blocks, 1,7-octadiyne and 1,6-diazidohexane, were chosen to serve as the alkyne and azide functionalities for dendrimer growth via click reactions with the azide and alkyne-dendrons, respectively. These two building blocks were employed together with the azide- and alkyne-functionalized Fr$\acute{e}$chet-type dendrons in a convergent strategy to synthesize two kinds of Fr$\acute{e}$chet-type dendrimers with different linear core units. This comparative efficiency of the click methodology supports the fast and efficient synthesis of dendritic-linear-dendritic materials with the tailor made core unit.

• 폴리머
• /
• 제36권3호
• /
• pp.295-301
• /
• 2012

선형 PEG단위를 덴드리머의 중심에 갖는 덴드리머의 합성을 위한 효율적인 연결 방법이 개발되었다. 합성전략은 알카인과 아자이드기 사이의 반응을 구리(1)촉매의 존재하에서 진행하는 클릭화학을 이용하였다. 덴드리머의 핵으로 작용할 수 있는 단위체인 옥타(에틸렌글리콜)디아자이드와 도데카(에틸렌글리콜)디아자이드를 합성하였고, 이 두 화합물의 아자이드기는 덴드리머의 형성에 이용되었다. 두 디아자이드화합물을 알카인 덴드론과 클릭 반응을 통해서 덴드리머의 핵의 선형 길이가 다른 두 종류의 덴드리머 제조에 대한 수렴형 합성법을 완성하였다.