Cu-Free “Click" Chemistry를 이용한 펩타이드 F-18 표지방법 및 PET연구를 위한 F-18 표지된 Ciprofloxacin의 합성 : Chapter I. Synthesis and Evaluation of 18F-Labeled N-Substituted Ciprofloxacin Derivative for the Imaging of Bacterial Infection with PET. Chapter II. Simple and Rapid Radiosynthesis of F-18 labeled Peptides by Strain-Promoted Catalyst-Free Click Chemistry for PET Imaging. Chapter III. Synthesis of F-18 labeled mono-, di- and tertameric cRGD Peptides via Copper-free "Click" Chemistry and microPET Imaging Study.

다국어 초록 (Multilingual Abstract)

Chapter I. Synthesis and Evaluation of 18F-Labeled N-Substituted Ciprofloxacin Derivative for the Imaging of Bacterial Infection with PET.
A series of new N-substituted ciprofloxacin derivatives were synthesized connected at N-1 position of ciprofloxacin by various linkers according to their structure activity relationship studies. Preliminary results indicated that most compounds tested in this study demonstrated comparable or better in vitro antibacterial activity against Gram-negative microorganism. Among these analogues, N4′-3-fluoropropylciprofloxacin (16) showed the significant antibacterial activity against E. coli strains (DH5R and TOP10) and a high binding affinity for DNA gyrase of bacteria. To develop bacteria-specific infection imaging agents for positron emission tomography (PET), no-carrier-added N4′-3-[18F]fluoropropylciprofloxacin ([18F]16) was prepared in two steps approach by radiofluorination of N4′-3-methanesufonyloxypropylciprofloxacin and followed by the hydrolysis using LiOH reagents, resulting in a 40% radiochemical yield (decay corrected for 100 min) via the tert-alcohol media radiofluorination protocol with high radiochemical purity (>99%) as well as high specific activity (149 ± 75 GBq/µmol). The agent was stable (>90%), as shown by an in vitro human serum stability assay. A bacterial uptake and blocking study of [18F]16 using authentic compound 16 in TOP10 cells demonstrated its high specific bacterial uptake. The results suggest that this radiotracer holds promise as a useful bacterial infection radiopharmaceutical for PET imaging.

Keywords: Fluoroquinolones; Ciprofloxacin derivatives; In vitro antibacterial activity; Fluorine-18; Positron emission tomography.

Chapter II. Simple and Rapid Radiosynthesis of F-18 labeled Peptides by Strain-Promoted Catalyst-Free Click Chemistry for PET Imaging.
As an effort in the development of more flexible 18F-labeled peptides, I introduce a facile efficient 18F-labeling protocol based on chemo-orthogonal strain-promoted cycloaddition using aza-dibenzocyclootyne-substituted peptides as precursors with 18F-azide synthon for high-throughput synthesis of various 18F-labeled peptide tracers under physiologically friendly reaction condition. 18F-PEG-azide [18F]2 was prepared by nucleophilic substitution of the corresponding PEG-azide mesylate precursor in 63% decay-corrected radiochemical yield with high radiochemical purity (> 99%) with total reaction time 75 min including HPLC purification. The SPAAC reaction and subsequent chemo-orthogonal purification reaction with azide resin proceeded quickly and selectively under physiologically friendly reaction condition (i.e., toxic chemical reagents-free, aqueous medium, room temperature, pH≈7), and provided four 18F-labelled tumor targetable bioactive peptides such as cyclic Arg-Gly-Asp (cRGD) peptide cRGD-ADIBOT-18F (specific activity, 51 GBq/µmol), bombesin (BBN) BBN-ADIBOT-18F (specific activity, 49.0 GBq/µmol), c-Met binding peptide (cMBP) cMBP-ADIBOT-18F (specific activity, 40.1 GBq/µmol) and apoptosis targeting peptide (ApoPep) ApoPep-ADIBOT-18F (specific activity, 55.0 GBq/µmol) in high radiochemical yield as direct injectable solutions without any HPLC purification and formulation process. In vitro binding assay and in vivo PET molecular imaging study using the 18F-labelled cRGD peptide also demonstrated successful application of our 18F-labeling protocol.

Keywords: Catalyst-free click chemistry; Fluorine-18; Peptide labeling; RGD; BBN; cMBP; positron emission tomography (PET) imaging.

Chapter III. Synthesis of F-18 labeled mono-, di- and tertameric cRGD Peptides via Copper-free "Click" Chemistry and microPET Imaging Study.
A series of 18F-labeled cRGD peptide have been developed based on chemo-orthogonal strain-promoted cycloaddition using aza-dibenzocyclootyne-substituted cRGD mono-, di- and tertameric peptides as precursors with 18F-azide synthon for positron emission tomography (PET) imaging of tumor αvβ3 integrin expression. In this study, the SPAAC reaction and subsequent chemo-orthogonal purification reaction with azide resin proceeded quickly and selectively under physiologically friendly reaction condition (i.e., toxic chemical reagents-free, aqueous medium, room temperature, pH≈7), provided mono-, di- and tertameric 18F-labelled tumor targetable bioactive peptides such as cRGD1-ADIBOT-18F, cRGD1-PEG4-ADIBOT-18F, cRGD2-ADIBOT-18F, cRGD2-PEG4-ADIBOT-18F, and cRGD4-PEG4-ADIBOT-18F in high radiochemical yield and high specific activity. In vitro binding assay and in vivo PET molecular imaging study using the 18F-labelled mono-, di- and tertameric cRGD peptides also demonstrated successful application of our 18F-labeling protocol.

Keywords: integrin αvβ3; RGD multimer; tumor angiogenesis; Catalyst-free click chemistry; Fluorine-18; RGD Peptide labeling; PET imaging.

목차 (Table of Contents)

• Contents
• Page
• Word of gratitude i
• Acknowledgements ii
• List of Abbreviations and Symbols vi
• Abstract viii
• Chapter I. Synthesis and Evaluation of 18F-Labeled N-Substituted Ciprofloxacin Derivative for the Imaging of Bacterial Infection with PET.
• 1. Introduction 2
• 2. Results and discussion 5
• 3. Conclusion 12
• 4. Experimental Section 13
• 5. References 24
• 6. NMR Spectrum (1H NMR and 13C NMR) 28
• 7. Specific activity 41
• Chapter II. Simple and Rapid Radiosynthesis of F-18 Labeled Peptides by Strain-Promoted Catalyst-Free Click Chemistry for PET Imaging.
• 1. Introduction 43
• 2. Results and discussion 47
• 3. Conclusion 60
• 4. Experimental Section 61
• 5. References 80
• 6. NMR Spectrum (1H NMR and 13C NMR) 86
• 7. MALDI-TOF-MS Data of Peptides 103
• Chapter III. Synthesis of F-18 Labeled mono-, di- and tertameric cRGD Peptides via Copper-free "Click" Chemistry and microPET Imaging Study.
• 1. Introduction 108
• 2. Results and discussion 110
• 3. Conclusion 124
• 4. Experimental Section 125
• 5. References 137
• 6. NMR Spectrum (1H NMR and 13C NMR) 144
• 7. MALDI-TOF-MS Data of Peptides 153
• 국문초록 159