Solid-Phase Synthesis of Linear and Cyclic Glycopeptoids

Peptides have been investigated as novel ligands to disease-related proteins. However, they possessed several drawbacks such as the sensitivity to proteases, limited cell permeability and poor bioavailability. Peptoids, oligimers of N-substituted glycines, were developed as promising peptidomimetics for the generation of chemically diverse libraries. And glycosylation, one of the most abundant post translation modifications in all living cells, plays important roles in cell-cell recognition, protein folding, stabilization, cell growth, etc. Thus, gylcopeptidomimetics can be served as biological probes for glycomics or chemical biology and lead compounds and candidates for drug discovery. As glycopeptidomimetics, we developed glycopeptoids in both linear and cyclic forms. The O-linked and N-linked sugar amine monomers were prepared in solution phase by employing different amine linkers for sequencing purpose. Though the introduction of sugar amine monomers into peptoid units was sensitive to various reaction conditions including the type of resin, solvents, concentration, etc, glycopeptoids were successfully synthesized on solid-phase. The linear glycopeptoids were efficiently sequenced by tandem mass spectrometry (MALDI-Tof/Tof) as we expected. Cyclic glycopeptoids in different length were also synthesized on solid phase by using various coupling reagents in high conversion efficiency. Both linear and cyclic glycopeptoids will be used as chemical tools for many biological applications.;펩타이드는 여러 생물학적 현상에서 다양한 역할을 하기 때문에 흥미 있는 물질로 여겨진다. 하지만 생체 내 효소에 의한 분해, 낮은 세포투과성 등의 제한성을 가지기 때문에 연구와 응용에 한계가 있다. 따라서, 의학, 생물학, 약학 등의 연구에서 이러한 단점을 극복할 수 있는 펩타이드 모방체의 개발은 매우 중요한 주제가 되었다. 펩타이드 여러 모방체의 하나인 펩토이드는 펩타이드의 곁가지가 펩타이드 결합의 질소로 이동된 형태로 펩타이드에 비해 세포투과성이 좋고, 세포 내 가수분해에 안정하며, 고체 상에서 합성이 쉽고, 수 많은 다양성을 부여할 수 있다. 본 연구에서는 세포 내 당단백질이나 당펩타이드의 역할 연구에 유용한 화학도구로서 당펩타이드 모방체인 당펩토이드의 고체상 합성에 대해 보고한다. 부분입체이성질체인 글루코오스, 갈락토오스, 만노오스에 서로 다른 분자량을 가지는 이음이를 연결하여 O-linked 또는 N-linked 탄수화물-아민 유도체들을 효율적으로 합성하였다. 그 후 고체상 합성시에 생성되는 연쇄 이합체를 줄이기 위해 수지의 종류와 당아민을 용해시키는 용매, 그리고 당 아민의 보호기에 따른 여러 실험을 하여 보다 효과적인 조건을 찾아내었다. 이를 이용하여 선형 당펩토이드를 고체상에서 높은 수율로 합성한 후 분리, 질량분석으로 확인할 수 있다. 그리고 선형 당펩토이드는 2차 질량분석 (MALDI-Tof/Tof)을 통해 효과적으로 배열을 확인할 수 있음을 보였다. 고리형 당펩토이드를 합성하기 위하여 서로 다른 길이와 당 아민의 서로 다른 위치를 가진 다양한 모델 화합물을 합성한 후 몇 가지 coupling agents를 사용하여 고리화 효율을 테스트하였고, 고체상에서 성공적으로 고리형 당펩토이드를 합성할 수 있었다. 개발된 선형 또는 고리형 당펩토이드는 다양한 생물학적 응용 연구에 유용한 화학도구로 사용될 수 있을 것이다.Solid-Phase Synthesis of Linear and Cyclic Glycopeptoids 1 Ⅰ. Introduction 2 Ⅱ. Results and Discussions 7 Ⅲ. Conclusion 21 Ⅳ. Experimental Section 22 Ⅴ. References 39 Appendix 42 국문 초록 5

고지방식이 마우스에서 무씨추출물의 항비만 효과

학위논문 (석사)-- 서울대학교 대학원 : 농생명공학부, 2017. 2. 이기원.Raphani Semen, a dried seed of radish, is used as a traditional Asian medicine to treat hypertension and digestive disorders. Sulforaphene (SFEN) is a main bioactive component in Raphani Semen, which has been shown to exhibit anti-adipogenesis effect in vitro. Here SFEN-enriched Raphani Semen extract (RSE) was prepared and effects of RSE on obesity, fatty liver and glucose intolerance were examined in mice fed a high-fat diet (HFD). Male C57BL/6J mice were fed a HFD for 16 weeks with or without RSE or black bean peptide (BBP) (n=9/group). Body weights of HFD-fed mice increased as compared to standard diet (SD), whereas both RSE and BBP suppressed HFD-induced increase in body weight after 16 weeks. In addition, RSE-supplementation inhibited HFD-induced fatty liver in mice by reducing hepatic triglyceride (TG) accumulation. To further investigate the underlying mechanisms involved in the reduction of body weight and liver TG in RES-supplemented mice, the expression levels of fatty acid metabolism related genes in epididymal white adipose tissue (eWAT) and liver were evaluated. HFD significantly decreased the expression levels of pgc1 as compared to SD, but RSE increased their levels in eWAT. HFD also reduced the expression levels of cpt-1a and acox1 in liver, whereas RSE significantly increased the levels of both genes. These data indicate that RSE suppressed HFD-induced obesity and fatty liver via upregulation of fatty acid metabolism. Moreover, RSE supplementation dramatically improved glucose tolerance as compared to HFD-fed mice. These results suggest that RSE can be used to prevent obesity and metabolic syndromes.Ⅰ. INTRODUCTION 1 Ⅱ. MATERIALS AND METHODS 5 2.1. Chemicals and reagents 5 2.2. Animal diets and animal study 7 2.3. Hematoxylin and eosin staining (H&E staining) 8 2.4. Lipid extraction of feces 8 2.5. Serum biochemistry 9 2.6. Real-time quantitative polymerase chain reaction (RT-qPCR) 11 2.7. Liver lipid extraction 14 2.8. Lipid quantitative analysis 15 2.9. Glucose tolerance test (GTT) 16 2.10. Statistical analysis 16 Ⅲ. RESULTS 17 3.1. Water and ethanol extraction methods were optimized to obtain a high yield of SFEN in Raphani Semen 17 3.2. RSE suppressed body weight gain by reducing fat mass in HFD-fed mice 19 3.3. RSE improved dyslipidemia in the blood serum 23 3.4. RSE upregulated the expression of lipolysis-, fatty acid oxidation-, and mitochondrial biogenesis-related mRNA in eWAT.25 3.5. RSE increased the expression of mitochondrial biogenesis related mRNA in BAT, and increased the expression of TGR5 and downstream genes related to energy expenditure in brown fat and skeletal muscle 29 3.6. RSE prevented hepatic steatosis caused by HFD feeding and increased the expression of fatty acid oxidation-related mRNA in the liver 33 3.7. RSE improved insulin sensitivity in HFD-fed mice 37 Ⅳ. DISCUSSION 41 Ⅴ. REFERENCES 45 Ⅵ. 국문 초록 48Maste