Method for preparing triptorelin

Abstract

The invention relates to the field of biological pharmacy, in particular to a method for preparing triptorelin. According to the method, a two-step cracking scheme is adopted, Sieber resin is taken as a solid-phase carrier, main chain resin is synthesized in a solid-phase manner, triptorelin with fully protected side chains is obtained through low-proportion acid cracking, triptorelin crude peptide is obtained through high-proportion acid cracking, and triptorelin is obtained through purification of the crude peptide. In order to reduce oxidation and other byproducts generated in the cracking process of tryptophan, a two-step cracking strategy is used in the invention. According to the method, generation of tryptophan oxidation byproducts in the cracking process is reduced, the yield is increased, the synthesis cost is greatly reduced, and the method is very beneficial to industrial production.

Description

Technical Field

[0001] This invention relates to the field of biopharmaceuticals, and more specifically, to a method for preparing triptorelin. Background Technology

[0002] Triptorelin is a potent GnRH agonist that, through sustained inhibition of sex hormone secretion, is a key drug for treating various hormone-dependent tumors (such as prostate cancer and breast cancer) and gynecological diseases (endometriosis and uterine fibroids). It is also used for central precocious puberty in children. In the reproductive field, it is commonly used to control pituitary downregulation before ovulation superstimulation, thereby preventing premature ovulation.

[0003] The sequence of triptorelin is Pyr-His-Trp-Ser-Tyr-D-Trp-Leu-Arg-Pro-Gly, containing two tryptophan residues (Trp). During cleavage, tryptophan oxidation impurities are easily generated. These impurities are similar in properties to the target product, making purification difficult and hindering their separation. This, in turn, affects product purity and production costs.

[0004] Patents CN101357936A and CN103012565A employ the Fmoc strategy solid-phase method to sequentially synthesize the main chain, followed by a one-step cleavage method to directly obtain the crude peptide. This method easily generates byproducts such as tryptophan oxidation during cleavage, resulting in low purity of the crude product, difficulty in separating impurities, and consequently, purification difficulties, affecting yield and cost. Patent CN117551176B uses a fragment condensation method to synthesize the main chain, followed by a one-step cleavage method to directly obtain the crude peptide. While this method achieves a high yield of triptorelin, the fragment condensation method increases the material ratio by 2-3 times compared to the one-step synthesis method, significantly increasing synthesis costs. Patent CN104387454A uses a combined solid-liquid method to synthesize the main chain and prepares triptorelin via a two-step cleavage method; however, the reaction requires strict zero-degree Celsius conditions, making the operating conditions quite demanding and significantly limiting industrial-scale production.

[0005] Therefore, those skilled in the art still look forward to methods for obtaining products with good quality at high product yields and low synthesis costs, especially new methods that reduce costs and waste liquid generation, which are essential and important for large-scale, industrialized production. Summary of the Invention

[0006] The technical problem to be solved by the present invention is that the existing methods for synthesizing triptorelin are prone to generating tryptophan oxidation byproducts during the cleavage process, which leads to difficulties in product purification, high costs, and the inability to obtain high-purity triptorelin. The present invention provides a new method for preparing triptorelin.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for preparing triptorelin includes the following steps: Using Sieber resin as the starting material, amino acids with protecting groups were sequentially linked according to the solid-phase synthesis method to obtain a fully protected resin, during which the Fmoc protecting group was sequentially removed. The first lysis buffer was added to the resin with the fully protected sequence to perform the first lysis, and the fully protected peptide with the side chain was obtained. A second lysis buffer was added to the fully protected peptide segment of the side chain for a second lysis to obtain crude triptorelin peptide. The crude peptide was then purified to obtain the triptorelin. The first lysis buffer is a DCM solution of TFA with a volume percentage of 0.5% to 1%; The second lysis buffer was prepared by mixing TFA, anisole, phenol, H2O, and DODT in a volume ratio of 80-90:1-10:1-10:1-10:1-5. This invention uses acid-sensitive Sieber resin as a solid-phase support to prepare the main-chain resin (fully protected sequence resin) via solid-phase synthesis technology. During the synthesis process, a low-ratio acid lysis was first used to obtain a triptorelin intermediate with fully protected side chains; subsequently, a high-ratio acid lysis was used to convert the intermediate into crude triptorelin peptide. Finally, after fine purification and lyophilization, a high-purity triptorelin final product was obtained.

[0008] The key innovation of this invention lies in its two-step cleavage strategy. During cleavage, tryptophan is prone to oxidation, generating various byproducts. This not only reduces the purity and yield of the target product but also increases the difficulty and cost of subsequent purification. By employing a stepwise cleavage approach, this invention effectively reduces the formation of tryptophan oxidation byproducts, significantly improving the yield and purity of the target product.

[0009] Furthermore, the method of this invention significantly reduces synthesis costs and improves production efficiency, demonstrating substantial industrial advantages. The successful application of this technology provides a novel solution for the efficient and low-cost synthesis of triptorelin, which is highly beneficial for large-scale industrial production and possesses broad application prospects and significant economic value.

[0010] Furthermore, in the solid-phase synthesis method, the amino deprotecting agent used is a DMF solution of piperidine with a volume percentage of 18% to 22%, or a DMF solution of DBU with a volume percentage of 1% to 2%.

[0011] Furthermore, in the solid-phase synthesis method, the coupling agent used is a mixture of DIC and Oxyma in an equimolar ratio.

[0012] Furthermore, in the first lysis, the mass-to-volume ratio of the fully protected sequence resin to the first lysis buffer was 0.8 g ~ 1.2 g: 10 mL, and the reaction conditions were room temperature reaction for 2 ~ 3 h.

[0013] Furthermore, the fully protected peptide sequence of the side chain is as follows: Pyr-His(Trt)-Trp(Boc)-Ser(tBu)-Tyr(tBu)-D-Trp(Boc)-Leu-Arg(Pbf)-Pro-Gly-NH2.

[0014] Furthermore, in the second lysis, the mass-to-volume ratio of the fully protected side-chain peptide to the second lysis buffer was 0.8 g ~ 1.2 g: 5 mL, and the reaction conditions were 200 ~ 300 r / min, 24 ~ 26 °C, and shaking reaction for 2 ~ 4 h.

[0015] Further purification was performed using reversed-phase high-performance liquid chromatography.

[0016] Furthermore, in the reversed-phase high-performance liquid chromatography, mobile phase A: 90% acetonitrile / water containing 0.1% TFA, mobile phase B: water containing 0.1% TFA; detection wavelength: 220 nm; flow rate: 10 mL / min; column specifications: 20×250 mm, 10 µm, 100 Å.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes acid-sensitive resin as a solid-phase support to prepare the main-chain resin via solid-phase synthesis. This method offers advantages such as high resin substitution value and low amino acid input, significantly reducing material costs. In the pyrolysis process, an innovative two-step pyrolysis strategy is employed to prepare crude triptorelin peptide. After purification, the target peptide triptorelin is obtained with a purity >99.5% and a yield >55%. This pyrolysis method effectively reduces byproducts such as oxidation of tryptophan during pyrolysis, significantly improving product yield and substantially reducing production costs. Most importantly, all steps in this process are completed at room temperature, making it simple to operate and possessing excellent potential for industrial scale-up, providing a reliable technical solution for large-scale production. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a novel synthetic process for preparing triptorelin proposed in this invention.

[0019] Figure 2 This is the chromatogram of the pure triptorelin peptide in Example 1 of the present invention.

[0020] Figure 3 This is the mass spectrum of the triptorelin pure peptide in Example 1 of the present invention.

[0021] Figure 4 This is a chromatogram of the triptorelin pure peptide in Example 2 of the present invention. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments, but this should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art, and the materials, reagents, etc. used in the following embodiments are commercially available unless otherwise specified.

[0023] In this invention, the liquid / liquid ratio refers to the volume ratio.

[0024] The meanings of the material abbreviations used in this invention are shown in Table 1.

[0025] Table 1. Meaning of material abbreviations used in this invention Example 1: A novel method for preparing triptorelin 1. Preparation of Fmoc-Gly-Sieber Resin (1) Weigh 1.00 g (0.60 mmol) of Sieber Resin (1% DVB, 100-200 mesh, 0.60 mmol / g) and add it to a 20 mL peptide solid-phase reactor. Add 10 mL of DCM solution to the reactor. Set the shaking speed of the shaker to 600 r / min and shake for 30 min. Drain the solution and add DMF solution to wash the resin twice. The washing solvent volume is 10 mL / time and the washing time is 3 min / time. The shaking speed of the shaker is 600 r / min.

[0026] (2) After washing, drain the solvent and add 8 mL of 20% piperidine / DMF solution to the resin in the reactor to remove the Fmoc protecting group. Shake at 600 r / min and 25℃ for 5 min, then drain the solution. Next, add another 8 mL of 20% piperidine / DMF solution to the resin and shake at 600 r / min and 25℃ for 15 min. Drain the solution and wash the resin 5 times with DMF solution (10 mL / 3 min / wash). Then, take a small amount of peptide resin and place it in a centrifuge tube, adding ninhydrin reagent. Heat the centrifuge tube at 110℃ for 3-5 min. Observe the color of the resin and solution in the centrifuge tube; a blue-purple solution indicates successful Fmoc removal.

[0027] (3) Weigh 0.535 g of Fmoc-Gly-OH (3.0 eq, 1.8 mmol) and 0.256 g of Oxyma (3 eq, 1.8 mmol) into a 50 mL beaker, dissolve them in DMF solution (7 mL), add 0.278 mL of condensing agent DIC (3 eq, 1.8 mmol) to the amino acid solution to activate the reaction for 5 min, then add it to the above-mentioned deprotected resin, and shake at 600 r / min and 25℃ for 1 h. After the reaction is complete, wash the resin 3 times with DMF solution (10 mL / 3 min / time). Then take a small amount of peptide resin and place it in a centrifuge tube, add ninhydrin reagent. Heat the centrifuge tube at 110℃ for 3-5 min. Observe the color of the resin in the centrifuge tube. The resin color is transparent and the solution is pale yellow, indicating that the amino acid coupling is successful.

[0028] 2. Resin stretching (1) Add 8 mL of 20% piperidine / DMF solution to the resin in the reactor to remove the Fmoc protecting group. Shake at 600 r / min and 25℃ for 5 min, then drain the solution. Then add another 8 mL of 20% piperidine / DMF solution to the resin, shake at 600 r / min and 25℃ for 15 min, drain the solution, and wash the resin 5 times with DMF solution (10 mL / 3 min / time). Then take a small amount of peptide resin and place it in a centrifuge tube, and add ninhydrin reagent. Heat the centrifuge tube at 110℃ for 3-5 min. Observe the color of the resin and solution in the centrifuge tube. If the solution is blue-purple, it indicates that the Fmoc removal is successful.

[0029] (2) According to the sequence composition, weigh 0.607 g of Fmoc-Pro-OH (3.0 eq, 1.8 mmol) and 0.256 g of Oxyma (3 eq, 1.8 mmol) at position 2 into a 50 mL beaker, add 7 mL of DMF solution to dissolve, add 0.278 mL of DIC (3 eq, 1.8 mmol) condensing agent to the amino acid solution to activate the reaction for 5 min, then add it to the above-mentioned deprotected resin, and shake at 600 r / min and 25℃ for 1 h. After the reaction is complete, wash the resin 3 times with DMF solution (10 mL / 3 min / time). Then take a small amount of peptide resin and place it in a centrifuge tube, add ninhydrin reagent. Heat the centrifuge tube at 110℃ for 3-5 min. Observe the color of the resin in the centrifuge tube. The resin color is transparent and the solution is pale yellow, indicating that the amino acid coupling is successful.

[0030] (3) Peptide chain elongation Following the sequence composition, steps (1) and (2) were repeated until the last amino acid was coupled. The resin was then washed alternately with the following procedure: DCM × 5 times (15 mL / 3 min / time), MeOH × 5 times (15 mL / 3 min / time). The resin was eventually in a shrunken state and placed in a vacuum drying oven. It was then vacuum dried at 25 °C to constant weight, yielding 2.265 g of peptide resin (Pyr-His(Trt)-Trp(Boc)-Ser(tBu)-Tyr(tBu)-D-Trp(Boc)-Leu-Arg(Pbf)-Pro-Gly-SieberResin), with a yield of 96.2%.

[0031] 3. First cleavage of the fully protected sequence For the first pyrolysis, the dried resin obtained above was added to 30 mL of pyrolysis buffer: 1% TFA / DCM (g 树脂 V 裂解液 =1:10), reacted at room temperature for 3 h. After the reaction was complete, the reaction solution was collected, concentrated under reduced pressure to an oily substance, then a small amount of DMF was added for reconstruction, precipitated in ice water, filtered, and the white solid was collected and dried under vacuum to constant weight, finally yielding 1.193 g of the fully protected peptide fragment (Pyr-His(Trt)-Trp(Boc)-Ser(tBu)-Tyr(tBu)-D-Trp(Boc)-Leu-Arg(Pbf)-Pro-Gly-NH2), with a yield of 94.3%.

[0032] 4. Second fragmentation of the fully protected sequence Weigh 1.193 g of the fully protected peptide fragment obtained in the above process. Add freshly prepared and pre-cooled K reagent lysis buffer at a ratio of 5 mL lysis buffer per gram of fully protected peptide. The K reagent lysis buffer was prepared with a volume ratio of TFA / phenol / water / anisole / ethylene dithiol = 82.5:5:5:5:2.5. The reaction was carried out at 200 r / min and 25℃ for 3 h with shaking. After the reaction was completed, the lysis buffer was slowly added dropwise to pre-cooled MTBE solution at a ratio of lysis buffer / methyl tert-butyl ether = 1:10 (v / v), resulting in the formation of a white precipitate. Then, centrifuge at 3500 rpm / min, discard the supernatant, add fresh MTBE solution, shake, centrifuge, discard the supernatant, and repeat the above centrifugation process 5 times. Collect the sludge-like white precipitate, dry it under vacuum at 25℃ to constant weight, and finally obtain 0.660 g of white solid crude peptide, with a yield of 95.3%.

[0033] 5. Reverse high performance liquid chromatography purification Weigh 31.1 mg of the crude product obtained during the above lysis process and purify the sample according to the gradient elution program in Table 2. The mobile phase A is 90% acetonitrile / water (containing 0.1% TFA), and the mobile phase B is water (containing 0.1% TFA). The detection wavelength is 220 nm, the flow rate is 10 mL / min, and the column specifications are 20×250 mm, 10 µm, and 100 Å.

[0034] Table 2 Purification and elution procedures for crude product cyclization solution The collected fractions were analyzed by MS and HPLC. The target fractions were combined and freeze-dried to obtain a total of 18.6 mg of triptorelin, with a yield of 59.8% and an HPLC purity of 99.859%. MS results showed [M+H] + =1311.6974, [M+2H] 2 + =656.3533, molecular weight correct. Triptorelin chromatogram as shown below. Figure 2 As shown, the mass spectrum is as follows Figure 3 As shown.

[0035] Comparative Example 1 1. Preparation of Fmoc-Gly-Sieber Resin (1) Weigh 1.00 g (0.60 mmol) of Sieber Resin (1% DVB, 100-200 mesh, 0.60 mmol / g) and add it to a 20 mL peptide solid-phase reactor. Add 10 mL of DCM solution to the reactor. Set the shaking speed of the shaker to 600 r / min and shake for 30 min. Drain the solution and add DMF solution to wash the resin twice. The washing solvent volume is 10 mL / time and the washing time is 3 min / time. The shaking speed of the shaker is 600 r / min.

[0036] (2) After washing, drain the solvent and add 8 mL of 20% piperidine / DMF solution to the resin in the reactor to remove the Fmoc protecting group. Shake at 600 r / min and 25℃ for 5 min, then drain the solution. Next, add another 8 mL of 20% piperidine / DMF solution to the resin and shake at 600 r / min and 25℃ for 15 min. Drain the solution and wash the resin 5 times with DMF solution (10 mL / 3 min / wash). Then, take a small amount of peptide resin and place it in a centrifuge tube, adding ninhydrin reagent. Heat the centrifuge tube at 110℃ for 3-5 min. Observe the color of the resin and solution in the centrifuge tube; a blue-purple solution indicates successful Fmoc removal.

[0037] (3) Weigh 0.535 g of Fmoc-Gly-OH (3.0 eq, 1.8 mmol) and 0.256 g of Oxyma (3 eq, 1.8 mmol) into a 50 mL beaker, dissolve them in DMF solution (7 mL), add 0.278 mL of condensing agent DIC (3 eq, 1.8 mmol) to the amino acid solution to activate the reaction for 5 min, then add it to the above-mentioned deprotected resin, and shake at 600 r / min and 25℃ for 1 h. After the reaction is complete, wash the resin 3 times with DMF solution (10 mL / 3 min / time). Then take a small amount of peptide resin and place it in a centrifuge tube, add ninhydrin reagent. Heat the centrifuge tube at 110℃ for 3-5 min. Observe the color of the resin in the centrifuge tube. The resin color is transparent and the solution is pale yellow, indicating that the amino acid coupling is successful.

[0038] 2. Resin stretching (1) Add 8 mL of 20% piperidine / DMF solution to the resin in the reactor to remove the Fmoc protecting group. Shake at 600 r / min and 25℃ for 5 min, then drain the solution. Then add another 8 mL of 20% piperidine / DMF solution to the resin, shake at 600 r / min and 25℃ for 15 min, drain the solution, and wash the resin 5 times with DMF solution (10 mL / 3 min / time). Then take a small amount of peptide resin and place it in a centrifuge tube, and add ninhydrin reagent. Heat the centrifuge tube at 110℃ for 3-5 min. Observe the color of the resin and solution in the centrifuge tube. If the solution is blue-purple, it indicates that the Fmoc removal is successful.

[0039] (2) According to the sequence composition, weigh 0.607 g of Fmoc-Pro-OH (3.0 eq, 1.8 mmol) and 0.256 g of Oxyma (3 eq, 1.8 mmol) at position 2 into a 50 mL beaker, add 7 mL of DMF solution to dissolve, add 0.278 mL of DIC (3 eq, 1.8 mmol) condensing agent to the amino acid solution to activate the reaction for 5 min, then add it to the above-mentioned deprotected resin, and shake at 600 r / min and 25℃ for 1 h. After the reaction is complete, wash the resin 3 times with DMF solution (10 mL / 3 min / time). Then take a small amount of peptide resin and place it in a centrifuge tube, add ninhydrin reagent. Heat the centrifuge tube at 110℃ for 3-5 min. Observe the color of the resin in the centrifuge tube. The resin color is transparent and the solution is pale yellow, indicating that the amino acid coupling is successful.

[0040] (3) Peptide chain elongation Following the sequence composition, steps (1) and (2) were repeated until the last amino acid was coupled. The resin was then washed alternately with the following procedure: DCM × 5 times (15 mL / 3 min / time), MeOH × 5 times (15 mL / 3 min / time). The resin was eventually shrunken and placed in a vacuum drying oven at 25 °C to constant weight. The final result was 2.250 g of peptide resin (Pyr-His(Trt)-Trp(Boc)-Ser(tBu)-Tyr(tBu)-D-Trp(Boc)-Leu-Arg(Pbf)-Pro-Gly-SieberResin), with a yield of 95.6%.

[0041] 3. Fragmentation of the fully protected sequence The pyrolysis is performed using a one-step method, and the specific steps are as follows: 2.250 g of the fully protected peptide resin obtained in the above process was weighed and added to freshly prepared and pre-cooled K reagent lysis buffer at a ratio of 10 mL of lysis buffer per gram of fully protected peptide resin. The K reagent lysis buffer was prepared at a volume ratio of TFA / phenol / water / anisole / ethylene dithiol = 82.5:5:5:5:2.5. The reaction was carried out at 200 r / min and 25℃ for 3 h with shaking. After the reaction was completed, the lysis buffer was slowly added dropwise to pre-cooled MTBE solution at a ratio of lysis buffer / methyl tert-butyl ether = 1:10 (v / v), resulting in the formation of a white precipitate. The mixture was then centrifuged at 3500 rpm, the supernatant was discarded, and fresh MTBE solution was added. The mixture was shaken, centrifuged, and the supernatant was discarded. This centrifugation process was repeated 5 times. The sludge-like white precipitate was collected and dried under vacuum at 25℃ to constant weight, finally yielding 0.640 g of white solid crude peptide, with a yield of 92.4%.

[0042] 4. Reverse high performance liquid chromatography purification Weigh 30.0 mg of the crude product obtained during the above lysis process and purify the sample according to the gradient elution program in Table 3. The mobile phase A is 90% acetonitrile / water (containing 0.1% TFA), and the mobile phase B is water (containing 0.1% TFA). The detection wavelength is 220 nm, the flow rate is 10 mL / min, and the column specifications are 20×250 mm, 10 µm, and 100 Å.

[0043] Table 3 Purification and elution procedures for crude product solution The collected fractions were analyzed by HPLC. The target fractions were combined and freeze-dried to obtain a total of 16.9 mg of triptorelin, with a yield of 56.3% and an HPLC purity of 98.5%. The chromatogram of triptorelin is shown below. Figure 4 As shown.

[0044] Through detailed comparative analysis of Example 1 and Comparative Example 1, the two-step cleavage strategy employed in this invention demonstrates significant advantages in the preparation of triptorelin. In Example 1, a carefully designed two-step cleavage process first utilizes low-ratio acid cleavage to precisely release the side-chain protecting groups, followed by high-ratio acid cleavage to efficiently complete the cleavage of the main chain. The resulting crude triptorelin peptide, after purification and lyophilization, exhibits satisfactory purity and yield. In contrast, Comparative Example 1 employs a traditional one-step cleavage method. Due to the tendency of tryptophan to undergo oxidation and other side reactions during cleavage, the product contains higher impurities, resulting in lower purity and yield compared to Example 1.

[0045] The two-step pyrolysis strategy of this invention cleverly avoids the drawbacks of traditional methods. By controlling the pyrolysis conditions in stages, it effectively reduces the formation of tryptophan oxidation byproducts, thereby significantly improving the purity and yield of triptorelin. This innovative method has not only achieved excellent results in laboratory-scale experiments but also demonstrated good reproducibility and stability in scale-up production, greatly improving production efficiency and reducing production costs. It provides an efficient, economical, and reliable solution for the industrial production of triptorelin. Therefore, the method of this invention has extremely high practical value and broad application prospects, making it very suitable for large-scale promotion and use, and is expected to bring significant economic and social benefits to related industries.

[0046] It should be noted that when numerical ranges are mentioned in the claims of this invention, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. To avoid redundancy, the present invention describes preferred embodiments.

[0047] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

Claims

1. A method for preparing triptorelin, characterized in that, Includes the following steps: Using Sieber resin as the starting material, amino acids with protecting groups were sequentially linked according to the solid-phase synthesis method to obtain a fully protected resin, during which the Fmoc protecting group was sequentially removed. The first lysis buffer was added to the resin with the fully protected sequence to perform the first lysis, and the fully protected peptide with the side chain was obtained. A second lysis buffer was added to the fully protected peptide segment of the side chain for a second lysis to obtain crude triptorelin peptide. The crude peptide was then purified to obtain the triptorelin. The first lysis buffer is a DCM solution of TFA with a volume percentage of 0.5% to 1%; The second lysis buffer is a mixture of TFA, anisole, phenol, H2O and DODT in a volume ratio of 80~90:1~10:1~10:1~10:1~5.

2. The method for preparing triptorelin according to claim 1, characterized in that, In the solid-phase synthesis method, the amino deprotecting reagent used is a DMF solution of piperidine with a volume percentage of 18% to 22%, or a DMF solution of DBU with a volume percentage of 1% to 2%.

3. The method for preparing triptorelin according to claim 1, characterized in that, In the solid-phase synthesis method, the coupling agent used is a mixture of DIC and Oxyma in an equimolar ratio.

4. The method for preparing triptorelin according to claim 1, characterized in that, In the first lysis, the mass-to-volume ratio of the fully protected sequence resin to the first lysis buffer was 0.8 g ~ 1.2 g: 10 mL, and the reaction conditions were room temperature for 2 ~ 3 h.

5. The method for preparing triptorelin according to claim 1, characterized in that, The fully protected peptide sequence of the side chain is as follows: Pyr-His(Trt)-Trp(Boc)-Ser(tBu)-Tyr(tBu)-D-Trp(Boc)-Leu-Arg(Pbf)-Pro-Gly-NH2.

6. The method for preparing triptorelin according to claim 1, characterized in that, In the second lysis, the mass-to-volume ratio of the fully protected side-chain peptide to the second lysis buffer was 0.8 g ~ 1.2 g: 5 mL, and the reaction conditions were 200 ~ 300 r / min, 24 ~ 26 °C, with shaking for 2 ~ 4 h.

7. The method for preparing triptorelin according to claim 1, characterized in that, Purification was performed using reversed-phase high-performance liquid chromatography.

8. The method for preparing triptorelin according to claim 7, characterized in that, In reversed-phase high-performance liquid chromatography, mobile phase A was 90% acetonitrile / water containing 0.1% TFA, and mobile phase B was water containing 0.1% TFA; detection wavelength was 220 nm; and flow rate was 10 mL / min. Column specifications: 20×250 mm, 10 µm, 100 Å.

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