Icaritin carbamate prodrug, and preparation method therefor and use thereof

Abstract

Provided are a preparation method for and the use of an icaritin carbamate prodrug and a salt thereof, which belong to the pharmaceutical field. In particular, provided are an icaritin carbamate prodrug represented by formula 3-N or 7-N and a pharmaceutically acceptable salt thereof, and a preparation method therefor and the use thereof. Specifically, the icaritin carbamate prodrug is formed by subjecting a main metabolic site (3-site or 7-site hydroxyl) of a natural flavonoid compound icaritin to structural modification by means of a chemical synthesis method, and introducing a suitable group at the position. Amines used in such carbamates are aliphatic amines. The presence of the carbamate structure reduces the phase II metabolism of icaritin in SD rats. Compared with an icaritin bulk drug, the 3-N-01 prodrug has a significantly improved oral bioavailability, making same the optimal prodrug. In clinical medication, the prodrug is expected to be able to reduce the administration dosage and improve patient compliance, and is expected to offer an effective strategy for improving the oral bioavailability of phenolic drugs.

Description

Icariin carbamate prodrugs and preparation method and application thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese Application No. 2023113402064, filed on October 17, 2023. Said application No. 2023113402064 is hereby incorporated by reference in its entirety. Technical Field

[0003] The present invention belongs to the field of pharmaceuticals, and in particular relates to carbamate prodrugs of icariin and pharmaceutically acceptable salts thereof, as well as preparation and application thereof. Background Art

[0004] Icaritin (ICT), also known as epimedin, is a natural 8-isopentenyl flavonoid and the primary active ingredient in Epimedium. It is marketed in China as a soft capsule for the first-line treatment of advanced liver cancer. ICT also exhibits anti-breast cancer, anti-osteoporosis, antioxidant, and anti-inflammatory activities.

[0005] ICT has poor water solubility. The hydroxyl groups at positions 3 or 7 of ICT are highly susceptible to Phase II metabolism in the intestine and liver, resulting in a strong first-pass effect. This results in very low bioavailability (absolute bioavailability of approximately 4.33%), limiting its clinical application. The structure of ICT is as follows:

[0006] Most existing technologies use formulation methods to improve the solubility of ICT. Although this has improved the bioavailability of ICT to a certain extent, it still has certain limitations, such as the use of a large amount of excipients, complex preparation methods, and low drug loading. Therefore, combining the structural characteristics of ICT, developing a method to improve the metabolic stability of ICT to enhance its bioavailability is a reliable and effective research strategy. Based on the above, we modified the main metabolic sites of ICT (hydroxyl groups at positions 3 or 7) with alkyl carbamates and synthesized carbamate prodrugs of ICT and their salts, aiming to reduce the phase II metabolism of ICT and reduce the first-pass effect. This not only achieves the purpose of improving the oral bioavailability of ICT, but also has a simple modification group and high drugability.

[0007] Summary of the Invention

[0008] The first object of the present invention is to provide an ICT carbamate prodrug and a pharmaceutically acceptable salt thereof.

[0009] The compound of the present invention has the following structural formula:

[0010] Wherein R1, R2, R3 and R4 each independently represent H or C 1-5 Alkyl, preferably H or C 1-2 alkyl.

[0011] The acid radical of the pharmaceutically acceptable salt is a pharmaceutically acceptable inorganic acid or organic acid.

[0012] The following provides definitions of various groups in the compounds of the present invention, which are used uniformly in the specification unless otherwise defined.

[0013] “C 1-5 "Alkyl" includes methyl, ethyl, propyl, butyl and pentyl.

[0014] The inorganic acid is hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, hydrobromic acid or hydroiodic acid;

[0015] The organic acid is formic acid, acetic acid, propionic acid, butyric acid, hydroxybutyric acid, malic acid, tartaric acid, an amino acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, trienesulfonic acid, camphorsulfonic acid, taurine, citric acid, fumaric acid, maleic acid, citric acid, succinic acid, cholic acid or deoxycholic acid.

[0016] The second object of the present invention is to provide a method for preparing ICT carbamate prodrugs and their salts.

[0017] The present invention adopts the following method to synthesize the above-mentioned compound, and the synthesis route is as follows:

[0018] The preparation method of ICT carbamate prodrugs is to react ICT with carbamoyl halide in an aprotic solvent under alkaline conditions;

[0019] The aprotic solvent is N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, diethyl ether, 1,4-dioxane, acetonitrile, dichloromethane, chloroform, benzene, toluene or a mixture of the above solvents; the base is triethylamine, N,N-diisopropylethylamine, pyridine, N,N-lutidine, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, sodium hydride, potassium hydride, sodium amide, potassium amide, alkyl lithium or lithium hexamethylsilylamide; and the carbamoyl halide is carbamoyl chloride or carbamoyl bromide.

[0020] The aprotic solvent is preferably acetonitrile, tetrahydrofuran or N,N-dimethylformamide; and the carbamoyl halide is preferably carbamoyl chloride.

[0021] The ICT carbamate prodrug is salified with an inorganic acid or an organic acid in a corresponding solvent to obtain a salt thereof. The solvent is selected from methanol, ethanol, propanol, isopropanol, dichloromethane, ethyl acetate, tetrahydrofuran, diethyl ether, 1,2-dimethoxyethane, acetonitrile and 1,4-dioxane.

[0022] A pharmaceutical composition comprising the ICT carbamate prodrug or a pharmaceutically acceptable salt thereof.

[0023] The third object of the present invention is to provide the above-mentioned ICT carbamate prodrugs or their salts as anti-tumor drugs for intravenous injection or oral administration.

[0024] The poor water solubility of ICT is an important reason for its low bioavailability. Therefore, investigating the equilibrium solubility of prodrugs in water is helpful to predict the dissolution and absorption of prodrugs in the body.

[0025] ICT is highly susceptible to Phase II metabolism in rats. The present invention aims to provide prodrugs that can significantly improve the pharmacokinetic properties of ICT, such as increasing oral bioavailability. Such prodrugs can reduce the glucuronide metabolism rate of ICT in vivo, ultimately achieving the goals of improving bioavailability, reducing dosage, and minimizing toxic side effects.

[0026] Table 1 lists some of the compounds synthesized by the present invention.

[0027] Table 1 Structures and structural identification information of some carbamate prodrugs

[0028] Beneficial effects of the present invention:

[0029] This invention utilizes the hydroxyl group at position 3 or 7 within the ICT molecule, structurally modified through chemical synthesis methods to introduce suitable groups at these positions to synthesize novel carbamate prodrugs. The amines used in these carbamates are all aliphatic amines, and the monomethylamine fragment is easily metabolized in the body, facilitating the release of the parent drug ICT. Furthermore, the presence of the carbamate structure increases the solubility and metabolic stability of these prodrugs, improving their oral bioavailability.

[0030] The present invention is of great significance for increasing the solubility and metabolic stability of ICT, improving its oral bioavailability, reducing its dosage, reducing its toxic side effects, and further searching for new ICT anti-tumor drugs. DETAILED DESCRIPTION

[0031] The present invention is further illustrated below with specific examples, but is not limited thereto.

[0032] According to the general synthetic route of ICT carbamates, the following compounds were prepared respectively.

[0033] Example 1

[0034] Under ice-cooling, slowly add a solution of ICT (10 mmol) in N,N-dimethylformamide dropwise to a mixture of N,N-dimethylformamide and 60% sodium hydride (30 mmol). Stir for 30 minutes, then add methylaminoformyl chloride (12 mmol). After addition, the reaction temperature is between 0°C and the boiling point of the solvent, preferably between 5°C and 10°C, for 2-4 hours. Monitor the reaction by thin-layer chromatography.

[0035] The reaction mixture was slowly poured into ice water and dichloromethane for extraction. The organic layer was separated and the aqueous layer was extracted with dichloromethane. The organic layers were combined, washed with saturated brine (×3), dried over anhydrous sodium sulfate, filtered, and concentrated to obtain an oil.

[0036] The oil was dissolved in dichloromethane, then adjusted to pH 2 with HCl in dichloromethane. Stirring was continued for 10 minutes. The solvent was evaporated under reduced pressure to obtain the crude product. Purification by silica gel column chromatography afforded compounds 3-N-01 and 7-N-01.

[0037] Example 2

[0038] Under ice-cooling, slowly add a solution of ICT (10 mmol) in N,N-dimethylformamide dropwise to a mixture of N,N-dimethylformamide and 60% sodium hydride (30 mmol). Stir for 30 minutes, then add ethylaminocarbonyl chloride (12 mmol). After addition, the reaction temperature is between 0°C and the boiling point of the solvent, preferably between 10°C and 30°C, for 2-4 hours. Monitor the reaction by thin-layer chromatography.

[0039] The reaction mixture was slowly poured into ice water and dichloromethane for extraction. The organic layer was separated and the aqueous layer was extracted with dichloromethane. The organic layers were combined, washed with saturated brine (×3), dried over anhydrous sodium sulfate, filtered, and concentrated to obtain an oil.

[0040] The oil was dissolved in dichloromethane, then adjusted to pH 2 with HCl in dichloromethane and stirred for 10 minutes. The solvent was evaporated under reduced pressure to obtain the crude product. Purification by silica gel column chromatography afforded compounds 3-N-02 and 7-N-02.

[0041] Example 3

[0042] Under ice, slowly add a solution of ICT (10 mmol) in N,N-dimethylformamide dropwise to a mixture of N,N-dimethylformamide and 60% sodium hydride (30 mmol). Stir for 30 minutes, then add N,N-dimethylcarbamoyl chloride (12 mmol). After addition, the reaction temperature is between 0°C and the boiling point of the solvent, preferably between 10°C and 25°C, for 2-4 hours. Monitor the reaction by thin-layer chromatography.

[0043] The reaction mixture was slowly poured into ice water and dichloromethane for extraction. The organic layer was separated and the aqueous layer was extracted with dichloromethane. The organic layers were combined, washed with saturated brine (×3), dried over anhydrous sodium sulfate, filtered, and concentrated to obtain an oil.

[0044] The oil was dissolved in dichloromethane, then adjusted to pH 2 with HCl in dichloromethane. Stirring was continued for 10 minutes. The solvent was evaporated under reduced pressure to obtain the crude product. Purification by silica gel column chromatography afforded compounds 3-N-03 and 7-N-03.

[0045] Example 4

[0046] Under an ice bath, slowly add 10 mmol of N,N-dimethylformamide solution dropwise to a mixture of N,N-dimethylformamide and 60% sodium hydride (30 mmol). Stir for 30 minutes, then add N,N-diethylcarbamoyl chloride (12 mmol). After addition, the reaction temperature is between 0°C and the boiling point of the solvent, preferably between 10°C and 25°C, for 2-4 hours. Monitor the reaction by thin-layer chromatography.

[0047] The reaction mixture was slowly poured into ice water and dichloromethane for extraction. The organic layer was separated and the aqueous layer was extracted with dichloromethane. The organic layers were combined, washed with saturated brine (×3), dried over anhydrous sodium sulfate, filtered, and concentrated to obtain an oil.

[0048] The oil was dissolved in dichloromethane, then adjusted to pH 2 with HCl in dichloromethane. Stirring was continued for 10 minutes. The solvent was evaporated under reduced pressure to obtain the crude product. Purification by silica gel column chromatography afforded compounds 3-N-04 and 7-N-04.

[0049] Example 5

[0050] Equilibrium solubility of ICT and ICT carbamate prodrugs in water

[0051] The poor water solubility of ICT is a major factor limiting its bioavailability. Therefore, examining the equilibrium solubility of the prodrug in water is helpful in predicting its dissolution and absorption in vivo. The equilibrium solubility of ICT and its ICT carbamate prodrug in water was determined by adding an excess of ICT API and ICT carbamate prodrug to an appropriate amount of water and shaking the mixture in an air-tight oscillator at 37°C until equilibrium was reached.

[0052] Table 2 Equilibrium solubility of ICT and its prodrugs in water

[0053] As shown in Table 2, compared with ICT, the equilibrium solubility of each prodrug compound in water is improved, and compound 3-N-01 has the highest equilibrium solubility in water.

[0054] Example 6

[0055] In vitro metabolic stability of ICT and ICT carbamate prodrugs

[0056] ICT's strong first-pass effect is a major factor limiting its bioavailability. Modifying the metabolic site of ICT can help reduce its phase II metabolism, reduce first-pass effect, and thus improve bioavailability. To determine whether prodrugs can improve their metabolic stability, we used an in vitro liver microsome incubation method to simulate in vivo metabolism. The metabolism of ICT and prodrug in rat liver microsomes was evaluated using the percentage of remaining ICT and its prodrug as an indicator. The metabolic half-lives are shown in Table 3.

[0057] Table 3 Phase II metabolic half-life of ICT and ICT carbamate prodrugs (t 1 / 2 )

[0058] The results showed that ICT is rapidly metabolized, while prodrug metabolism is slowed, especially the 3-N series carbamate prodrugs with significantly increased metabolic stability. The results indicate that the carbamate strategy can improve the Phase II metabolic stability of ICT.

[0059] Example 7

[0060] Pharmacokinetic study in rats

[0061] Sprague-Dawley rats in the experimental and control groups were gavaged with olive oil solutions of ICT and its carbamate prodrug (120 mg / kg of ICT each). The plasma concentrations of ICT and its prodrug were determined, and the results are shown in Table 4.

[0062] Table 4 Pharmacokinetic parameters of rats after oral administration of ICT or ICT carbamate prodrug (n=4)

[0063] The pharmacokinetic parameters of ICT and its carbamate prodrug after oral administration are shown in Table 4. Compared with ICT alone, the C max and AUC 0-t were significantly increased, while the C of ICT in the blood of rats after administration of other prodrugs was max and AUC 0-tThe increase was insignificant or nonsignificant. Administration of 3-N-01 significantly increased ICT blood concentrations. Compared to ICT alone, the bioavailability of ICT and the combined bioavailability of ICT and prodrug in rats after 3-N-01 administration was 4.5 times and 13.9 times higher than that of ICT alone. In vitro studies also demonstrated that 3-N-01 increased solubility and metabolic stability, making it an optimal prodrug.

Claims

1. Icariin carbamate prodrug or a pharmaceutically acceptable salt thereof, characterized in that: Its structural formula is as follows: Wherein R1, R2, R3, and R4 are each independently selected from H, C 1-5 alkyl; The acid radical of the pharmaceutically acceptable salt is a pharmaceutically acceptable inorganic acid or organic acid.

2. The icariin carbamate prodrug or a pharmaceutically acceptable salt thereof according to claim 1, characterized in that: The C 1-5 The alkyl group includes methyl, ethyl, propyl, butyl and pentyl; the inorganic acid is hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, hydrobromic acid or hydroiodic acid, and the organic acid is formic acid, acetic acid, propionic acid, butyric acid, hydroxybutyric acid, malic acid, tartaric acid, amino acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, trienesulfonic acid, camphorsulfonic acid, taurine, citric acid, fumaric acid, maleic acid, citric acid, succinic acid, cholic acid or deoxycholic acid.

3. The icariin carbamate prodrug or a pharmaceutically acceptable salt thereof according to claim 1 or 2, characterized in that: Selected from the following compounds:

4. The method for preparing the icariin carbamate prodrug or its salt according to claim 1, characterized in that: It is prepared by the reaction of icariin with carbamoyl halide in an aprotic solvent under alkaline conditions; The aprotic solvent is N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, ether, 1,4-dioxane, acetonitrile, dichloromethane, chloroform, benzene, toluene or a mixture of the above solvents; the base is triethylamine, N,N-dimethylformamide, tetrahydrofuran, ether, 1,4-dioxane, acetonitrile, dichloromethane, chloroform, benzene, toluene or a mixture of the above solvents. Isopropylethylamine, pyridine, N,N-dimethylpyridine, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, sodium hydride, potassium hydride, sodium amide, potassium amide, alkyl lithium or hexamethylsilylamide lithium; the carbamoyl halide is carbamoyl chloride or carbamoyl bromide.

5. The method for preparing the icariin carbamate prodrug or its salt according to claim 4, characterized in that: The aprotic solvent is acetonitrile, tetrahydrofuran or N,N-dimethylformamide; and the carbamoyl halide is carbamoyl chloride.

6. A pharmaceutical composition, characterized in that It comprises the icariin carbamate prodrug or a pharmaceutically acceptable salt thereof as claimed in claim 1.

7. Use of the icariin carbamate prodrug or its salt according to any one of claims 1 to 3 in the preparation of anti-tumor drugs.

8. The use according to claim 7, characterized in that It is administered intravenously or orally.

Images