Liver-targeting compound and oligonucleotide conjugate and uses thereof

Abstract

The present application belongs to the technical field of oligonucleotide drug delivery, and relates to a liver-targeting compound and a conjugate and application thereof, wherein the liver-targeting compound has a four-target-head structure. The present application prepares an oligonucleotide conjugate by using the liver-targeting compound, wherein the conjugate realizes specific targeting delivery of a therapeutic oligonucleotide to the inside of a liver cell by four N-acetylgalactosamine ligands in the structure which have specific affinity for asialoglycoprotein receptors on the surface of mammalian liver cell, so as to achieve the purpose of treating diseases, and the conjugate can maintain high stability of the delivered oligonucleotide while also having excellent delivery efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oligonucleotide drug delivery, and particularly relates to a liver-targeting compound and conjugate and application thereof. BACKGROUND

[0002] Oligonucleotide compounds have important therapeutic applications in medicine, and in specific therapeutic applications, oligonucleotides and analogs thereof can be selected to be expressed only in specific tissues or locations, so as to treat related diseases at specific target sites. Oligonucleotides and analogs thereof, as representative tissue-specific active agents, have made some progress in the application as therapeutic agents, but there is still a need to improve their pharmacological properties, so as to target delivery to specific tissues and organs, so as to improve their biological activity and efficacy. In particular, the liver is the most widely studied target for delivery of targeted conjugate delivery technology. SUMMARY

[0003] In view of the deficiencies of the prior art, in a first aspect, the present application provides a liver-targeting compound having the structure shown in formula (I):

[0004]

[0005] wherein R1 is as shown in formula (II), R2 is an oxygen atom, a sulfur atom or a carbon atom, preferably a carbon atom; n is any integer from 4 to 10, preferably 4; R is a tert-butyloxycarbonyl group, a trityl group, a 4,4'-dimethoxytrityl group, a 4,4' or 4"-trimethoxytrityl group, preferably a 4,4'-dimethoxytrityl group, i.e. DMTr; M is an H ion, an ammonium ion, an alkali metal ion or an alkaline earth metal ion, etc., preferably an H ion;

[0006]

[0007] wherein R3 is an H ion, an acetyl group, a benzyl group or a tert-butyloxycarbonyl group, etc., preferably an acetyl group; n1 is any integer from 1 to 6, preferably 1.

[0008] Further, the structure of the liver-targeting compound is shown in formula (I-1):

[0009]

[0010] i.e. R1 is as shown in formula (II), R2 is a carbon atom; n is 4; R is DMTr; M is an H ion; R3 is an acetyl group (Ac); and n1 is 1.

[0011] In a second aspect, the present application provides an oligonucleotide conjugate having the structure shown in formula (III):

[0012]

[0013] wherein R1 is as shown in formula (II), R2 is an atom such as oxygen, sulfur or carbon, preferably carbon; n is 4-10, preferably 4; Q is a phosphate, carbonate or sulfate, preferably phosphate; and Nu is a functional oligonucleotide.

[0014] The oligonucleotide conjugate, wherein the functional oligonucleotide Nu is selected from one of small interfering RNA, microRNA, antisense nucleic acid, mRNA fragment; alternatively, the functional oligonucleotide Nu is a single-stranded oligonucleotide or a double-stranded oligonucleotide.

[0015] Further, the oligonucleotide conjugate has a structure as shown in formula (III-1):

[0016]

[0017] Alternatively, the functional oligonucleotide is a single-stranded oligonucleotide, P in formula (III-1) is linked to the terminal of the single-stranded oligonucleotide, further, P in formula (III-1) is linked to the 3' terminal of the single-stranded oligonucleotide; alternatively, the functional oligonucleotide is a double-stranded oligonucleotide, the double-stranded oligonucleotide comprises a sense strand and an antisense strand, P in formula (III-1) is linked to the 3' terminal of the sense strand.

[0018] Further, the double-stranded oligonucleotide is siRNA, i.e. small interfering RNA.

[0019] In a third aspect, the present application provides a preparation method of the liver targeting compound of formula (I-1):

[0020] Compound 10 is reacted with compound 6 in the presence of an amide condensing agent to prepare compound 11, compound 11 is catalytically hydrogenated to remove the benzyl group to obtain compound 12, compound 12 is again reacted with compound 11 in the presence of a condensing agent to obtain compound 13 with four targeting heads, compound 13 is hydrogenated to remove the benzyl group to obtain compound 14, finally, compound 14 is reacted with compound 12 to obtain compound 21, compound 21 is reacted with succinic anhydride to introduce an ester group at the secondary alcohol position to obtain compound (I-1), and the reaction scheme is as shown below:

[0021]

[0022] Further, the synthesis method of compound 10: compound 7 is reacted with compound 8 (benzylamine) to obtain disubstituted compound 9, followed by hydrolysis to obtain compound 10, and the reaction scheme is as shown below:

[0023]

[0024] Further, the synthesis method of the compound 6: compound 2 reacts with acetic anhydride to obtain the acetyl-protected compound 3, cyclization to obtain compound 4, compound 4 reacts with 4-(N-tert-butoxycarbonylamino)-1-butanol to open the ring to obtain compound 5, and hydrochloric acid is used to remove the Boc protecting group to obtain compound 6, and the reaction formula is as shown below:

[0025]

[0026] In a fourth aspect, the present application provides a preparation method of the oligonucleotide conjugate of formula (III):

[0027] The compound of formula (I) is connected to a controlled-pore glass (CPG) solid-phase carrier by an amide condensing agent to obtain a solid-phase carrier of the compound of formula (I), which is used for solid-phase synthesis to prepare the oligonucleotide conjugate of formula (III).

[0028] The compound of formula (I) is used to prepare the conjugate of formula (III), and the conjugate of formula (III) realizes delivery of the therapeutic oligonucleotide to the inside of the liver cells by four N-acetylgalactosamine ligands in the structure, which have specific affinity for the asialoglycoprotein receptor on the surface of the mammalian liver cells, so as to achieve the purpose of treating diseases.

[0029] Further, the preparation method of the oligonucleotide conjugate of formula (III-1): the compound of formula (I-1) is connected to a controlled-pore glass (CPG) solid-phase carrier by an amide condensing agent to obtain a solid-phase carrier of formula (III'-1) of the compound of formula (I-1), which is used for solid-phase synthesis to prepare the oligonucleotide conjugate of formula (III-1), and the reaction formula is as shown below:

[0030]

[0031] In a fifth aspect, the present application provides the use of the liver-targeting compound of formula (I) and the oligonucleotide conjugate of formula (III) in the preparation of an oligonucleotide drug.

[0032] Further, the specific target gene of the oligonucleotide of the oligonucleotide drug is selected from at least one of PCSK9, HBV, TTR and AGT.

[0033] The present application has the following beneficial effects:

[0034] The compound of formula (I) provided by the application has a novel four-target head structure compared with existing structures, and has the advantages of simple and controllable preparation method, low cost and simple synthesis route. The application provides the compound of formula (I) and a preparation method, and the compound of formula (I) is used to prepare the conjugate of formula (III), the synthesis route and the purification step of the conjugate of formula (III) are simple, the cost is low, meanwhile, the four N-acetylgalactosamine ligands in the structure of the conjugate of formula (III) have specific affinity for the asialoglycoprotein receptor on the surface of mammalian liver cells, so that the therapeutic oligonucleotide is specifically targeted and delivered to the inside of the liver cells, so as to achieve the purpose of treating diseases, and the conjugate of formula (III) can maintain the high stability of the delivered oligonucleotide while having excellent delivery efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 A bar chart of TTR mRNA expression in mice in the embodiment of the application;

[0036] Figure 2 A bar chart of TTR protein expression in mice in the embodiment of the application. DETAILED DESCRIPTION

[0037] The principles and characteristics of the application are described below in combination with examples, and the examples are only used to explain the application and are not used to limit the scope of the application.

[0038] Embodiment:

[0039] 1. Preparation of compound 10:

[0040]

[0041] Compound 7 (6-bromo-hexanoic acid methyl ester, 7.33 g, 35.0 mmol), compound 8 (benzylamine, 1.5 g, 14.0 mmol), anhydrous potassium carbonate (5.8 g, 42.0 mmol), potassium iodide (1.16 g, 7.0 mmol) were weighed into a reaction bottle, 50 mL of anhydrous ethanol was added to stir and suspend, the reaction system was placed in a 82℃ condition and stirred and heated to reflux, and the reaction was carried out for 12 h. The heating was stopped, the temperature was reduced to room temperature, the solvent ethanol was removed under reduced pressure, 30 mL of water and 30 mL of dichloromethane were added, stirred and separated into layers, the organic phase was separated, the water phase was extracted with dichloromethane twice, the organic phases were combined, and after drying and removing the solvent, a yellow oily liquid of a crude product was obtained. Column chromatography purification was carried out, and gradient elution was carried out with petroleum ether: ethyl acetate = 10:1~3:1 to obtain 3.71 g of compound 9 in the form of a light yellow oily liquid, and the yield was 73%.

[0042] Compound 9 (3.7 g, 10.17 mmol) was weighed into a reaction flask, dissolved in ethanol (10 mL) with stirring, and sodium hydroxide (1.63 g, 40.68 mmol) was added to the reaction solution. The reaction system was heated and stirred at 40°C for 2 h, and then cooled to room temperature. The ethanol was removed under reduced pressure, and the solution was dissolved in water and washed with dichloromethane twice. The aqueous phase was adjusted to pH 2-3 with 1 N hydrochloric acid, and solid sodium chloride was added to saturation. The product was extracted with dichloromethane three times, and the organic phases were combined, dried, and the solvent was removed to obtain the product, intermediate 10, as a yellow oily liquid (2.63 g, 77% yield).

[0043] MS m / z [M+H]+ (ESI): 336.05.

[0044] 2. Preparation of compound 6

[0045]

[0046] Compound 2 (50.0 g, 232 mmol) was added to a reaction flask, and acetic anhydride (165 mL) was added. Pyridine (220 mL) was added under ice bath conditions, and DMAP (2.4 g, 19.7 mmol) and triethylamine (23.5 g, 232 mmol) were added. After stirring overnight at room temperature, the mixture was filtered, the filter cake was washed with toluene and water, and the white solid compound 3 was obtained by drying under reduced pressure at 45°C (73.2 g, 81% yield).

[0047] Compound 3 (20.0 g, 51.4 mmol) was added to a reaction flask, and 4A molecular sieve-dried dichloromethane (100 mL) was added. Trimethylsilyl trifluoromethanesulfonate (13.7 g, 61.7 mmol) was added under argon protection, and the mixture was stirred overnight at room temperature. Triethylamine (15.6 g, 154.2 mmol) was added, and the mixture was stirred. The solvent and triethylamine were removed under reduced pressure to obtain compound 4 as an oil (32.1 g), which was used directly in the next step without purification.

[0048] Compound 4 from the previous step was dissolved in 4A molecular sieve-dried 1,2-dichloroethane (120 mL), and 4-(N-tert-butoxycarbonylamino)-1-butanol (10.2 g, 54 mmol) was added. Trimethylsilyl trifluoromethanesulfonate (2.3 g, 10.3 mmol) was added at room temperature, and the mixture was stirred overnight. Saturated sodium bicarbonate solution (60 mL) and water (80 mL) were added to the reaction solution, and the mixture was partitioned. The organic phase was washed with water (80 mL x 1), 10% citric acid aqueous solution (100 g x 2), dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure to obtain crude product 5 as a brownish yellow oil (16.5 g). The two-step yield was 62%.

[0049] Compound 5 (16.0 g, 30.8 mmol) was added to a reaction flask, and hydrochloric acid in dioxane (4.0 mol / L, 65 mL) was added. The mixture was stirred at room temperature for 3 h. The solvent was removed under reduced pressure to give compound 6 as a dark amber foam, 12.3 g, in 95% yield. The compound was used in the next step without further purification.

[0050] MS m / z [M+H]+ (ESI): 418.06.

[0051] 3. Preparation of compound of formula (I-1)

[0052]

[0053] Compound 10 (6.0 g, 17.9 mmol) was added to a reaction flask and dissolved in dichloromethane (90 mL). N,N-diisopropylethylamine (9.2 g, 71.1 mmol) was added, followed by HATU (2-(7-azabenzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate, 14.3 g, 37.6 mmol). The mixture was stirred at room temperature for 3 h. Compound 6 (15.7 g, 37.6 mmol) was dissolved in dichloromethane (60 mL), and the solution was added dropwise to the reaction mixture. The mixture was stirred at room temperature for 4 h. Saturated sodium chloride solution (100 mL) was added, and the mixture was separated. The dichloromethane phase was dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure to give a crude product as a red oil. Dichloromethane (30 mL) and methyl tert-butyl ether (120 mL) were added, and the mixture was stirred for 1 h. The mixture was filtered to give a yellow solid. The above crystallization procedure was repeated twice to give compound 11, 9.1 g, in 45% yield.

[0054] Compound 11 (9.0 g, 7.9 mmol) was added to a reaction flask, and water (100 mL) was added and stirred to dissolve. 5% Pd-C (1.0 g) was added, and the mixture was stirred at room temperature for 3 h under hydrogen. The Pd-C was removed by filtration, and sodium chloride was added to the filtrate to saturation. The mixture was extracted with dichloromethane (70 mL x 4). The organic phases were combined, dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure to give an off-white solid, 8.0 g, which was compound 12, in 96% yield.

[0055] Compound 10 (1.27 g, 3.8 mmol) was added to a reaction flask, and dichloromethane 10 mL was added and stirred. HATU (3.03 g, 8 mmol) was added, and stirred at room temperature for 3 h. Compound 12 (7.95 g, 7.6 mmol, dissolved in 20 mL dichloromethane) was added, and stirred at room temperature for 2 h. 10% sodium chloride solution 100 g was added, and the mixture was separated, and the dichloromethane phase was separated, and washed with 10% sodium chloride solution (50 g x 4), and the dichloromethane phase was dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure to obtain a brown solid crude product, and 10 mL dichloromethane and 100 mL ethyl acetate were added, and the supernatant was poured out, and a gummy solid was obtained at the bottom of the flask. 25 mL acetonitrile was added, and the gummy solid was dissolved by ultrasonic, and left to stand overnight, and a gummy solid was obtained by filtration. The above crystallization operation was repeated three times to obtain a yellowish gummy solid 2.81 g, a yield of 31%, which was compound 13.

[0056] Compound 13 (2.75 g, 1.15 mmol) was added to a reaction flask, and 5% Pd-C (0.7 g) was added, and hydrogen was introduced at room temperature for 3 h. The Pd-C was removed by filtration, and sodium chloride solid was added to the water to saturation, and dichloromethane was extracted (20 mL x 4). The organic phase was combined, and dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure to obtain a yellowish-brown solid 2.51 g, a yield of 95%, which was compound 14.

[0057] Compound 20 (672 mg, 1.1 mmol) was added to a reaction flask, and dichloromethane 5 mL was added, and HATU (543 mg, 1.43 mmol) was further added, and stirred at room temperature for 3 h. Compound 14 (2.50 g, 1.09 mmol, dissolved in 5 mL dichloromethane) was added to the reaction system, and stirred at room temperature for 3 h. 10% sodium chloride solution 10 g was added to the reaction, and stirred and separated, and the organic phase was washed with 10% sodium chloride solution (10 g x 3), and dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure to obtain a brown oil. Dichloromethane 4 mL and ethyl acetate 30 mL were added, and a solid was precipitated, and a off-white solid 725 mg was obtained by filtration, a yield of 23%, which was compound 21.

[0058] Compound 21 (620 mg, 0.21 mmol) was added to a reaction flask, and dichloromethane 5 mL was added. Succinic anhydride (210 mg, 2.1 mmol), DMAP (4-dimethylaminopyridine, 256 mg, 2.1 mmol), and triethylamine (323 mg, 3.2 mmol) were further added, and reacted at room temperature for 24 h, and the reaction was monitored by LC-MS. 10% sodium chloride solution 10 g was added to the reaction, and the mixture was separated, and the organic phase was washed with saturated sodium chloride (8 g x 3). The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed under reduced pressure to obtain a crude product. 8 mL dichloromethane was added to dissolve the crude product, and ethyl acetate 100 mL was further added, and a solid was precipitated, and the solid was dried under reduced pressure to obtain a solid 580 mg, a purity of 71% at 214 nm.

[0059] Preparation liquid phase separation purification, type Gilson GX281, column: waters X-bridge C18, 19*250mm, 10μm. Mobile phase A: ammonium bicarbonate aqueous solution, pH = 8-9; mobile phase B: acetonitrile. Flow rate 20 mL / min, monitoring wavelength 214 nm, each needle injection volume 6.0μl, gradient elution, to obtain white solid powder 180mg, namely compound (I-1) HPLC purity 98.84%.

[0060] HRMS m / z [M-H]-(ESI): 2988.3838. 1 H NMR (400 MHz, Chloroform-d) δ δ 7.90 - 7.79 (m, 9H), 7.36 - 7.25 (m, 4H), 7.25 - 7.14 (m, 5H), 6.91 - 6.82 (m, 4H), 5.24 (t, J = 7.0 Hz, 4H), 5.18 (t, J = 6.6 Hz, 4H), 5.03 (d, J = 5.5 Hz, 4H), 4.99 (p, J = 4.4 Hz, 1H), 4.25 (qd, J = 12.1, 4.3 Hz, 8H), 4.11 (ddd, J = 9.1, 7.1, 5.5 Hz, 4H), 3.96 (dt, J = 6.4, 4.4 Hz, 4H), 3.90 - 3.78 (m, 8H), 3.71 - 3.58 (m, 8H), 3.52 (qdd, J = 13.6, 6.1, 4.4 Hz, 2H), 3.28 - 3.16 (m, 20H), 2.77 - 2.63 (m, 4H), 2.43 (tt, J = 8.1, 1.3 Hz, 6H), 2.21 (dt, J = 16.9, 8.4 Hz, 10H), 2.09 (d, J = 15.6 Hz, 36H), 2.02 (s, 12H), 1.72 - 1.50 (m, 45H), 1.46 - 1.28 (m, 24H).

[0061] 4. Synthesis of solid phase support of compound (I-1)

[0062] Compound (I-1) (59.8 mg, 20 μmol) was added to DMF 10 mL, then benzotriazole-N, N, N', N'-tetramethyluronium hexafluorophosphate (HBTU, 19 mg, 50 μmol), N, N-diisopropyl ethylamine (DIEA, 16.2 mg, 125 μmol) were added, and then amino-modified solid phase carrier (CPG-NH2) 0.4 g was added, and the reaction was oscillated at 25 °C for 24 h. After the reaction was completed, acetonitrile and dichloromethane were used for washing in sequence. Then 20% acetic anhydride / acetonitrile was added, and the reaction was oscillated at 25 °C for 24 h. After the reaction was completed, acetonitrile and dichloromethane were used for washing in sequence, and the solid phase carrier target product was obtained, and the GalNAc loading was measured to be 24.38 μmol / g.

[0063] 5. Preparation of siRNA conjugate

[0064] Synthesis of siRNA targeting mouse TTR gene, with galactose molecule cluster linked at the 3' end of SS strand (compound of formula (I-1)).

[0065] SS strand (5'-3'):

[0066] AmsAmsCmAmGmUmGfUmUfCfUfUmGmCmUmCmUmAmUmAmAm (SEQ ID NO 1)

[0067] AS strand (5'-3'):

[0068] UsUfsAmUmAmGfAmGmCmAmAmGmAmAfCmAfCmUmGmUmUmsU msUm (SEQ ID NO 2)

[0069] wherein the lower case letter f represents that the nucleotide adjacent to the left of the letter f is a 2'-fluorine-modified nucleotide, the lower case letters a, g, c, u are 2'-OMe-modified nucleotides, and the lower case letter s represents that the two nucleotides adjacent to the left and right of the letter s are connected by a phosphorothioate bond.

[0070] The 2'-O-methyl nucleoside monomer required for siRNA synthesis was purchased from Shanghai Zhiwei Technology Development Co., Ltd.

[0071] 3% dichloroacetic acid as deprotection agent, 0.25M 5-ethylthio-1H-tetrazole acetonitrile solution as activator, N, N-dimethyl-N'-(3-thio-3H-1, 2, 4-dithiazole-5-yl) formamidine pyridine solution as sulfuration reagent, 0.05M iodine / pyridine / water solution as oxidizing agent, 20% acetic anhydride acetonitrile solution as capping agent A, 20% acetonitrile / N-methyl imidazole / pyridine solution as capping agent B, and the above related synthesis reagents were purchased from Suzhou Keluoma Biotechnology Co., Ltd.

[0072] Each RNA single strand was synthesized by phosphoramidite solid phase synthesis. The synthesis was initiated with a solid support and nucleoside phosphoramidite monomers were added according to the synthesis procedure using a DNA synthesizer. Each nucleoside monomer addition included four steps of deprotection, coupling, oxidation or sulfurization, and capping.

[0073] After the solid phase synthesis was completed, the oligonucleotides were ammoniated with 28% ammonia at 55°C for 16 hours. The supernatant was concentrated and dried, purified using a Resource 15Q column, eluted with a gradient of sodium bromide solution, and the DMTr was removed using 3% trifluoroacetic acid solution. The purified oligonucleotide was collected, desalted using a dextran gel G25 gel column, and the obtained oligonucleotide was collected, lyophilized, and its purity was detected by ion pair chromatography. The mass of the target product was analyzed by mass spectrometry. The obtained single-stranded oligonucleotide was quantified by ultraviolet light, and complementary pairing was performed according to the equimolar ratio. The double-stranded siRNA was formed by dissolving it in water according to the conventional annealing method, and the concentration was adjusted to the required concentration for the experiment.

[0074] Test:

[0075] 1. Inhibition of TTR mRNA expression in mice

[0076] Eight-week-old C57BL / 6 mice (Jixi Pharmaceutical, SPF, female) were randomly divided into groups. On day 0, each siRNA conjugate was administered to the skin of the mouse shoulder and neck, and normal saline was administered as a control group. On days 0, 7, 14, 21, and 28, 3 mice from each group were euthanized, and liver tissue samples were taken. The mRNA expression level of TTR in mouse liver tissue was detected by real-time fluorescent PCR. Total RNA was extracted from the liver using the RNAeasy Mini kit (Qiagen, catalog number 74104), and cDNA was obtained by reverse transcription according to the High Capacity cDNA Reverse Transcription Kits (Thermo Fisher, catalog number: 4368814) for RT-PCR. The glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene was used as an internal reference gene, and the RT-PCR method shown in Table 1 was used to detect the mRNA expression level of mouse TTR and GAPDH using Taqman probe primers (Table 2). The mRNA expression level of mouse TTR was calculated using the ΔΔCt method, and the effect of I-1-siRNA on TTR mRNA was calculated.

[0077] Table 1 Real-time fluorescent quantitative PCR conditions

[0078]

[0079] Table 2 Detection primer sequences

[0080]

[0081] Figure 1 The bar graph of TTR mRNA expression in mice in the embodiments of the present application is shown in the figure. The conjugate of the present application has the ability of delivering small nucleic acids to the liver, and has good liver TTR mRNA inhibitory activity in vivo. It is further illustrated that the conjugate connected with siRNA can improve the targeting and stability of oligonucleotide drugs to liver cells by using its structural characteristics, and can effectively solve the drug delivery problem.

[0082] 2. Inhibition of TTR protein expression in mice in vivo

[0083] 8-week-old C57BL / 6 mice (Jisui Pharmaceutical, SPF, female) were randomly divided into groups. On day 0, 100 μL of each siRNA conjugate was administered to the skin of the shoulder and neck of the mice, and at the same time, normal saline was administered as a control group. Plasma samples were taken on days 0, 7, 14, 21, and 28, respectively, and the content of TTR protein in the plasma was determined by ELISA. The TTR protein content in the plasma on day 0 was normalized.

[0084] Figure 2 The bar graph of TTR protein expression in mice in the embodiments of the present application is shown in the figure. The conjugate of the present application has the ability of delivering small nucleic acids to the liver, and can significantly inhibit the expression of TTR protein.

[0085] It can be understood that the present application is described by some embodiments, and those skilled in the art know that various changes or equivalent replacements can be made to these features and embodiments without departing from the spirit and scope of the present application. In addition, under the guidance of the present application, these features and embodiments can be modified to adapt to specific conditions and materials without departing from the spirit and scope of the present application. Therefore, the present application is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present application are within the scope of the present application.

Claims

1. A liver-targeting compound, characterized in that, The structural formula is shown as formula (I-1): Formula (I-1).

2. An oligonucleotide conjugate, characterized in that, The structure is shown as formula (III-1): Formula (III-1); Wherein, Nu is siRNA.

3. Use of the liver targeting compound of claim 1 or the oligonucleotide conjugate of claim 2 in the preparation of an oligonucleotide drug; the specific target gene of the oligonucleotide drug is TTR.

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