GANIRELIX

Originator

Antagon,Organon

Uses

Decapeptide LH-RH antagonist. Ganirelix is used in treatment of infertility.

Definition

ChEBI: Ganirelix is a polypeptide.

Manufacturing Process

The abbreviations for common aminoacids are those recommended by IUPACIUB Comission on Biochemical Nomenclature. Other abbreviations useful in describing the replacements of aminoacids in the natural LH-RH peptide are following:
Nal(2) - 3-(2-naphthyl)alanyl; p-Cl-Phe - 3-(p-chlorophenyl)alanyl; Pal(3) - 3- (3-pyridyl)alanyl; ; hArg(Et)2 - NG,NG - bis(ethtyl)homoarginyl; Boc - tbutyloxycarbonyl.
Ganirelix (N-Ac-Nal(2)-D-pCl-Phe-D-Pal(3)-Ser-Tyr-D-hArg(Et)2-Leu-hArg(Et)2- Pro-Ala-NH2) was prepared using the following side chain protection protocol: salt protection for L- and D-hArg(Et)2 (as the chloride) and t-butyl protection for serine.
Amino acids were added to the Nα-Boc-D-Ala-O-Resin (1.0 mmol of resin was replaced in the reaction vessel of 5.0 L Vega 296 automated solid phase peptide synthesizer; in the following sequence:
Acetic anhydride
An acetylation (capping of the resin) was done after Ala, Pro and Leu with N,N'-diisopropyl carbodiimide - 1-hydroxybenztriazole (HBt). Excess HBt (2 equiv.) was used for the coupling of the basic amino acids, hArg(Et)2 and Pal(3).
The following protocols were used to remove the Nα-protecting group following each addition.
Program A: The resin was first washed with CH2Cl2 1 times/1 min, TFA-CH2Cl2 (40/60) 1 times/1 min, TFA-CH2Cl2 (40/60) 1 times/30 min, CH2Cl2 2 5 times/1 min, Et3N-CH2Cl2 (5/95) 3 times/1 min, CH2Cl2 4 times/1 min.
Program B: The resin was first washed with CH2Cl2 1 times/1 min, 4-4.5 N HCl in CH2Cl2/i-PrOH (1/1) 1 times/1 min, 4-4.5 N HCl in CH2Cl2/i-PrOH (1/1) 1 times/30 min, CH2Cl2 3 times/1 min, DMF 1 times/1 min, Et3N-CH2Cl2 (5/95) 3 times/1 min, DMF 1 times/1 min, CH2Cl2 4 times/1 min.
After each deprotecting and washing step, following protocol A or B, the next amino acid in sequence was added and the resin washed with CH2Cl2 3 times/1 min, MeOH 4 times/1 min, DMF 2 times/1 min and CH2Cl2 4 times/1 min.
Program A was used for the removal of the protecting groups on Ala, Pro, LhArg(Et)2, Leu and D-Nal(2).
Program B was used for the removal of the protecting groups on D-hArg(Et)2, Tyr, Ser, D-Pal(3) and p-Cl-Phe.
The crude peptide was first dissolved in 2 M acetic acid and converted to its acetate salt by passage through a column of AG3-X4A resin (Bio-Rad). The acetate was subjected to chromatography on a silica gel column (CH2Cl2/iPrOH/MeOH/H2O/HOAc solvent); the acetate fractions dissolved in H2O and loaded onto a reversed-phase column (Vydec C-18, 15-20 μ), and purified using acetonitrile/TEAP (pH 3). Fractions of the desired purity were combined and diluted with water and reloaded on a reversed-phase HPLC column, then washed with 1% acetic acid in water. The peptide was stripped with a mixture of MeOH/CH3CN/HOAc/H2O (44/50/1/5). The residue was dissolved in acetic acid and precipitated over ether, filtered, washed with ether and dried under vacuum. Amino acid analyses were performed on a Beckman 119CL amino acid analyzer. Samples for amino acid analyses were hydrolyzed with 6 N HCl at 110°C for 20 hrs. Analytical HPLC was performed on a Spectra Physics 8800 chromatograph. Synthesis of ganirelix was confirmed by the presence of a main peak at rt 18 min; no other peak over 1% was noted at rt 16 min.

Therapeutic Function

LHRH antagonist