Design And Synthesis Of TPO-mimic Peptide With Photolabile Protecting Strategy

The nuclear energy and technology are quite closely linked to our life, their exsit increased the dangerous of surferring us the radiation damage even they make our life convenient. The radiation damage is a kind of acute, delayed or chronic organism damage coursed by ionizing radiation. The blood system was first responsed while the organism was suffered nuclear radiation. The clinic feature performs the decrease of neutrophil, lymphocyte, white blood cell, red blood cell and blood platelet. The blood platelet is an important ingredient to maintain the normal function of blood, which was differentiated by mature megakaryocyte in marrow. It plays important rules in hemostasis and wound healing. Now most medicine used for blood system was focused on the decrease of white blood cell and red blood cell, but very few for blood platelet, therefore it has important significance to develop a thrombopoietic agent.Thrombopoietin(TPO) is a kind of cytokines effects on the megakaryocyte-platelet production system, which will induce the megakaryocyte differentiated to platelet. TMP is a peptide contains 14 amino acid residues, which has the similar function with TPO but quite different in structure, therefore the homologous immunoreaction was prevented. After reviewed various kind of thrombopoietic drugs, we moidified the the TPO-mimic peptide TMP as lead compound to obtain more effective molecules, which will overcome the drawback of TMP in pharmacokinetics, therefore established the theoretical and experimental basis to explore new drugs to prevent and cure the injuries of nuclear radiation. The thesis has made such main progress:1. The multi-mode microwave assisted PEGyated PS resin. The polystyrene is still the main material in solid phase synthesis, but the low swelling property in polar solvent limited the application in some cases. The resin was offered a better solvent compability after PEGlytation. The traditional chemical PEGylation method needs longer time and wastes more raw materials. We discovered that the multi-mode microwave will overcome such drawback, which will complete the PEGylated of the polustyrene resin. Compared with the traditional method, the multi-mode microwave assistance operated easily, fast and efficient, and which provide a reference for fast preraration of PS-PEG resin in laboratery. The final target products were synthesized on the self-produced PEGylated resin as solid supports.2. Prepared a fast photo-deprocted molecule used for peptide synthesis. It is usually need the Fmoc-tBu strategy or Boc-Bn strategy for linear peptide synthesis, but a special protecting strategy is essential for the synthesis of complex peptide, cyclic peptide and site-specific modification. The photolabile protecting group was a kind of molecule that will decompose with the effect of light but the chemical effect, therefore cooperate with the other protecting group will make it easy to synthesis or modify the complex compound. In the solid-phase peptide synthesis, considering of the transmittance of resin and the active of the peptide molecule, the use of the photolabile protecting strategy is limited. After summarized several photolabile protup, we chose the 2-(2-nitrophenyl)-ethyl(Npp) group as the research object. By using the easily available 2-nitroethylbenzene and 2-nitromethylbenzene as the starting material, 5 different photolabile protecting group was synthesized. After the react mechanism and other properties were investigated, a satisfied photolabile was obtained. This group is quite stable to the Fmoc-tBu strategy, and the photolysis is rather rapid, which will complete deprotected in the polystyrene resin. This strategy facilitates the synthesis of the cyclicpeptide and site-specific modification, thus plays important roles for prepraring complex peptide.By using the self-established photo chemical method, combined with the Fmoc-tBu strategy, a marine cyclopeptide was synthesized. Compared with the report, it has the advances of less synthesis step, lower synthesis costing, avoid the repeatedly acidolysis, the side chain of Trp is free of protection. The structure of cyclic peptide was identified by HRMS, 1HNMR and 13 CNMR. Such a method was used for modification of the TPO-mimic peptide, and therefore a serious side chain modified compound was obtained. The final product was purified by RP-HPLC, and the structure was identified by MALDI-TOF MS.3. After summarized several photolabile resin, three photolabile linkers were prepared and 6 photolabile resins were obtained, by anchoring to the polystyrene resin and PEGylated resin as solid phase respect. To investigate the loading rates and the acidic and alkaline stability of the resin, amino acids were anchored. After the photolysis were performed and compared, a high effective photolabile resin was discovered, which supplied reference for preparing full-protected peptide fragment. Meanwhile, the acid labile property of trigger benzoin resin was discovered, which the resin can be used for routine peptide synthesis.4. The research based on the TMP as the lead compound, designed a serious analogue include D-configuration amino acid replacement, acylation of the N terminal, modification of the main chain, modification of the side chain and the cyclic compound. Results of activity screening to part of them indicated that the 5-bromo ferulic acid acylated TMP is very effective in increasing the number of red blood cell, hemoglobin and platelet, which implied that acylation of N-terminal will increase the lipid solubility, thus reinforce the thrombopoietic activity, which is worthy for further research.This thesis established a rapid and efficient photolabile method used for peptide synthesis which is capable with the Fmoc-tBu strategy. 16 mimic peptide derivatives were synthesized altogether. By using the hematopoietic injury model in mice caused by nuclear radiation, the activity of mimic peptides was preliminary screened. Early results suggested that acylation of the TMP N-terminal by anti-radiation agent would change the oil-water partition coefficients, therefore improve the effect of increasing red blood cell, hemoglobin and platelet.