Proceedings book download - 5Z.com

Proceedings of the 31 st European Peptide SymposiumMichal Lebl, Morten Meldal, Knud J. Jensen, Thomas Hoeg-Jensen (Editors)European Peptide Society, 2010Efficient Synthesis of Fertirelin Acetate as a ReproductiveControl Drug: A GnRH Hormone AnalogueFmoc-Pro-OPipyridine 25%H 2 N-Pro-OVahid Dianati, Armin Arabanian, and Saeed BalalaiePeptide Chemistry Research Group, K. N. Toosi University of Technology, Tehran,P.O. Box 15875-4416, Iran, balalaie@kntu.ac.irIntroductionFertirelin acetate is an analogue for Gonadotropin Hormone Releasing Hormone (GnRH),also known as Luteinizing-hormone releasing hormone (LHRH). GnRH is a tropic peptidehormone responsible for the release of FSH and LH from the anterior pituitary which aresynthesized and released from neurons within the hypothalamus. Fertirelin acetate (1) is aLHRH agonist intended for the treatment of ovarian follicular cysts in mammals and for theimprovement of conception rates. It induces ovulation in mammals, and it is used as a drugfor cows.Nowadays, Pfizer Company produces this drug [1-4]. In continuation of our researchin the synthesis of GnRH analogues, herein we wish to report the synthesis of Fertirelinacetate. It was shown that the 100- and 200µg doses of fertirelin acetate increase pregnancyrates in virgin heifers and tended to improve pregnancy rates in suckled cows when injectedduring the midluteal phase after insemination.Results and DiscussionFertirelin acetate as a GnRH analogue was syntheiszed via a combination of solid andsolution phase peptide synthesis manually on the 2-chlorotrityl chloride resin using thestandard Fmoc strategy. Cleavage of peptide off the surface of 2-chlorotrityl resin needs amild acidic condition. Meanwhile, the ethylamidation of produced N-terminal nonapeptidewas done using ethylammonium hydrochloride in the presence of NMM (N-methylmorpholine) in NMP as solvent. The product was purified using preparative HPLC andstructure was confirmed by the MALDI-Mass spectrometry data. Orthogonality has animportant role in selection of the type of resin, and strategy of synthesis.Fmoc-Pro-OHDIEATBTU/DIEAPiperidine 25%Cl1)Fmoc-Arg(Pbf)-OHFmoc-Arg(Pbf)-Pro-OH 2 N-Arg(Pbf)-Pro-OpGlu-His(Trt)-Trp(Boc)-Ser(tBu)-Tyr(tBu)-Gly-Leu-Arg(Pbf)-Pro-OTFA 1%pGlu-His(Trt)-Trp(Boc)-Ser(tBu)-Tyr(tBu)-Gly-Leu-Arg(Pbf)-Pro-OHEtNH 3 ClNMMNMPpGlu-His(Trt)-Trp(Boc)-Ser(tBu)-Tyr(tBu)-Gly-Leu-Arg(Pbf)-Pro-NHEtTFA 81.5%CocktailpGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-NHEtScheme 1. Synthetic procedure for thesynthesis of fertirelin acetate.Fertirelin acetate is an amidatedC-terminal peptide. There are differentmethods for the synthesis of C-terminalamidated peptides such as; a) enzymaticamidation, [4] b) the combination ofrDNA technology with chemicalmodification of the C-terminus, c) usingof amide resins in SPPS, d) usingcarboxypeptidase in the presence ofammonia, e) conversion of the C-terminusof peptides to the methylester andaddition of ammonia at low temperature.All of the reported methods havesome drawbacks such as: a) laboriousreaction conditions, b) high price ofenzymes and limitation of solubilityparameters, c) using of ammonia oralkylamines as gas and performing thereaction at low temperature, d) the use ofHF for the cleavage of the peptide fromthe surface of the resin. Separation andpurification of enzymes need more timeand energy [6]. According to thesedrawbacks, we used ethylammoniumhydrochloride in solution phase for thesynthesis of ethylamidated form ofC-terminal peptides.326