Study On The Synthesis Of Mastoparan-M And Ergopeptide

(1)Mastoparan-M（MP-M）is a cationic active peptide containing 14 amino acid residues extracted from bee venom,and the peptide has amphipathic properties.Studies have proved that the peptide has a wide range of biological activities,such as penetrating cell membranes,hemolysis,antimicrobial,antiviral,antineoplastic,secretory stimulation.Therefore,the peptide has broad application prospects.In this study,wasp venom peptide was synthesized by Fmoc solid-phase synthesis strategy.According to the amino acid sequence and molecular weight of MP-M,Wang resin was selected as the carrier for synthesizing the peptide.The degree of substitution was controlled to be 0.7 mmol/g.The degree of substitution of Wang resin was determined by Fmoc quantitative absorption method.By optimizing the reaction conditions,the best conditions were found that DCM as a solvent for resin swelling,HBTU/HOBt/DIEA as a condensation agent for peptide synthesis,add 3.0eqv.Fmoc amino acid and condensing agent,20%4-methylpiperidine in DMF as the deprotection reagent,trifluoroacetic acid（TFA）:methyl phenyl sulfide:H₂O:phenol:1,2-ethanedithiol=82.5:5:5:5:2.5,（v:v）as cutting reagents.The condensation reaction and deprotection reaction were qualitatively detected by the Kaiser method during the synthesis.At the same time,the chemical structure of the synthetic peptide was identified and characterized by mass spectrometry（ESI-MS）,infrared（IR）,circular dichroism（CD）and other analytical methods.The purity of the pure peptide was97%by HPLC and the final yield of the polypeptide was 56%.The synthesis strategy is simple,reproducible and feasible.（2）Ergocyclic peptides and their derivatives,such as ergotamine and bromocriptine,are widely used in the treatment of central nervous system（CNS）diseases.The unique ternary epoxy peptide fragments make ergocyclic peptides drugs have specific pharmacological activities.However,the content of ergocyclic peptides isolated from natural products is low and the fermentation period is long.Up to now,only two synthetic routes for the construction of epoxy tripeptide fragments have been reported.Among them,R-（+）-2-isopropyl-2-benzyloxymalonate monoethyl ester is the key intermediate for the synthesis of epoxy tripeptide fragments,but its synthetic routes are complex and the yield is low.It has been proved that lipase Novozym 435 can effectively catalyze the synthesis of monoethyl R-（+）-2-isopropyl-2-benzyloxymalonate,and this method has many advantages:mild reaction conditions,high enantioselectivity,environmental friendliness and short reaction route.Under the optimum reaction conditions,the conversion rate was 50%,and the ee value of the product was as high as 99%.Based on the previous work of our group,we plan to design a synthetic route with simple process,mild reaction conditions and high yield.In the subsequent synthesis of cyclic tripeptides in this synthetic route,many attempts on the newly designed route have been made in this paper.Although the synthesis of cyclic tripeptides has not been completed effectively,this paper first explores the chemical-enzymatic method,which provides a new idea for the synthesis of ergocyclic peptides.