Synthesis, EPR characterization and chitosan labelling of triarylmethyl radicals Dissertation Zur Erlangung des akademischen Grades Doctor rerum naturalium (Dr. rer. nat.) vorgelegt der Naturwissenschaftlichen Fakultät I Biowissenschaften der Martin-Luther-Universität Halle-Wittenberg von M.Sc. Marwa Aly El-metwaly Mohamed Elewa Geboren am 16. August 1982 in Port Said, Ägypten Gutachter: 1. Prof. Dr. habil. Peter Imming 2. Prof. Dr. habil. Karsten Mäder 3. Prof. Dr. habil. Klaus Müller Halle (Saale), den 30.07.2015 Verteidigt am 06.11.2015 TO MARYAM & TAMER Table of contents Table of contents Table of contents _________________________________________________________ A List of abbreviations ______________________________________________________ E Abstract ________________________________________________________________ G English version ______________________________________________________________ G German version ______________________________________________________________ I 1. Introduction ___________________________________________________________ 1 1.1. Electron paramagnetic resonance (EPR) _____________________________________ 1 1.2. Spin probes _____________________________________________________________ 5 1.2.1. Tetrathia-TAM radicals as spin probes for oxygen, pH, redox status and thiol concentration measurements __________________________________________________________________________ 7 1.2.1.1. Tetrathia-TAM radicals and oxygen mapping ____________________________________ 7 1.2.1.2. Tetrathia-TAM radicals metabolism and reactions ________________________________ 11 1.2.1.3. Tetrathia-TAM radicals and interaction with biological macromolecules ______________ 15 1.2.1.4. Tetrathia-TAM radicals as pH-sensitive spin probes ______________________________ 16 1.2.1.5. Tetrathia-TAM radicals and redox status determination ___________________________ 19 1.2.1.6. Tetrathia-TAM radicals and thiol concentration measurement ______________________ 20 1.2.1.7. Tetrathia-TAM radicals and superoxide radical measurement _______________________ 21 1.2.2. Tetrachloro-TAM radicals _______________________________________________________ 22 1.2.2.1. Synthesis of tetrachloro-TAM radicals _________________________________________ 22 1.2.2.2. Stability of tetrachloro-TAM radicals __________________________________________ 24 1.2.2.3. Reactivity of tetrachloro-TAM radicals ________________________________________ 24 1.2.2.4. Different derivatives of tetrachloro-TAM radicals ________________________________ 25 1.2.2.5. Tetrachloro-TAM radicals as spin probes for various pharmaceutical applications ______ 27 1.3. Aim of the work _________________________________________________________ 31 2. Tetrathiatriarylmethyl radicals ___________________________________________ 32 2.1. Introduction ____________________________________________________________ 32 2.2. Experimental ___________________________________________________________ 33 2.2.1. Materials and general methods for synthesis and analytical characterization _______________ 33 2.2.2. Sample preparation for EPR spectroscopic characterization. ____________________________ 33 2.2.3. EPR spectroscopy _____________________________________________________________ 33 2.3. Results and Discussion ___________________________________________________ 33 A Table of contents 2.3.1. Synthesis of different tetrathia-TAM radicals ________________________________________ 33 2.3.2. Characterization of hydrophilic trityl radicals in aqueous solutions ______________________ 35 2.3.2.1. Influence of ion strength, osmolarity, and pH value _______________________________ 35 2.3.2.2. Impact of viscosity _________________________________________________________ 35 2.3.3. EPR spectroscopic characterization of lipophilic tetrathia-TAM radicals in an oily solution __ 36 2.3.4. Oxygen sensitivity _____________________________________________________________ 37 2.3.5. Encapsulation of tetrathia-TAM esters and properties of the resulting nanocapsules (NCs) ___ 38 2.4. Conclusion _____________________________________________________________ 39 2.5. Syntheses ______________________________________________________________ 39 3. Tetrachlorotriarylmethyl radicals _________________________________________ 51 3.1. Introduction ____________________________________________________________ 51 3.2. Experimental ___________________________________________________________ 51 3.2.1. Materials and general methods for synthesis and analytical characterization _______________ 51 3.2.2. Sample preparation for EPR spectroscopic characterization ____________________________ 51 3.2.3. EPR spectroscopy _____________________________________________________________ 51 3.3. Results and Discussion ___________________________________________________ 52 3.3.1. Synthesis of different tetrachloro-TAM radicals _____________________________________ 52 3.3.2. EPR characterization ___________________________________________________________ 53 3.3.3. Oxygen calibration of radicals 24 and 25 in an oily solution ___________________________ 55 3.3.4. Spin labelling of a nucleoside ____________________________________________________ 56 3.4. Syntheses ______________________________________________________________ 64 4. PTMTC and 13C-PTMTC _______________________________________________ 83 4.1. Introduction ____________________________________________________________ 83 4.2. Experimental ___________________________________________________________ 83 4.2.1. Materials and general methods for synthesis and analytical characterization _______________ 83 4.2.2. Sample preparation for EPR spectroscopic characterization ____________________________ 83 4.2.3. Continuous wave (CW-EPR) spectra ______________________________________________ 84 4.2.4. Pulse X-band EPR _____________________________________________________________ 84 4.3. Results and discussion ___________________________________________________ 84 4.3.1. Synthesis of tetrachlorotriarylmethyl tricarboxylic acid (PTMTC) and its 13C labelled analog (13C-PTMTC) _________________________________________________________________________ 84 4.3.2. EPR characterization ___________________________________________________________ 85 4.3.3. CW-EPR spectrum _____________________________________________________________ 86 B Table of contents 4.3.4. Influence of pH value on 13C-PTMTC line width _____________________________________ 87 4.3.5. Influence of viscosity on 13C-PTMC line width ______________________________________ 88 4.3.6. Influence of oxygen on PTMTC line width _________________________________________ 89 4.3.7. Influence of temperature on 13C-PTMTC line width __________________________________ 91 4.3.8. The accelerated aging (by increasing temperature) method _____________________________ 93 4.3.9. Cell lysate study _______________________________________________________________ 95 4.4. Conclusion _____________________________________________________________ 95 4.5. Syntheses ______________________________________________________________ 96 5. Spin labelling of polymers (chitosan and carboxymethyl chitosan) _____________ 100 5.1. Introduction ___________________________________________________________ 100 5.1.1. Structure of CS and CMC ______________________________________________________ 100 5.1.2. Properties of CS and CMC _____________________________________________________ 102 5.2. Experimental __________________________________________________________ 103 5.2.1. Materials and general methods for synthesis and analytical characterization ______________ 103 5.2.2. Characterization of CS and CMC conjugates _______________________________________ 103 5.2.2.1. UV-Vis spectroscopy ______________________________________________________ 103 5.2.2.2. EPR measurements _______________________________________________________ 103 5.3. Results and discussion __________________________________________________ 103 5.3.1. Preparation of CS and CMC conjugates ___________________________________________ 103 5.3.2. UV-Vis spectroscopy __________________________________________________________ 104 5.3.3. EPR spectroscopy ____________________________________________________________ 106 5.4. Conclusion ____________________________________________________________ 107 5.5. Syntheses _____________________________________________________________ 107 6. Tetraoxatriarylmethyl radicals __________________________________________ 109 6.1. Introduction ___________________________________________________________ 109 6.2. Results and Discussion __________________________________________________ 110 6.3. Syntheses _____________________________________________________________ 114 7. Summary and Outlook _________________________________________________ 118 8. References __________________________________________________________ 128 9. Appendices ____________________________________________________________ I C Table of contents 9.1. Materials ________________________________________________________________ I 9.2. General methods for synthesis and analytical characterization ____________________ I 9.3. LDH-release and cell activity/proliferation ___________________________________ II 9.4. Acknowledgement ________________________________________________________ III 9.5. Curriculum vitae _________________________________________________________ IV 9.6. List of publications _______________________________________________________ V 9.6.1. Research articles _______________________________________________________________ V 9.6.2. Conference