Silybin derivative, preparation method therefor and use thereof

Abstract

The present invention relates to a silybin derivative, a preparation method therefor and the use thereof, belonging to the technical field of chemistry. In the present invention, by means of introducing a hydrophilic sodium sulfonate group into silybin, silybin is sulfonated to prepare a new compound having a good water solubility, i.e. sodium silybin sulfonate. This increases the solubility of silybin in water, improves the pharmacokinetic characteristics of silybin from a pharmacokinetic perspective, and increases the affinity therewith for organisms and the bioactivity of silybin. The compound can be formulated into an injection for use in clinical treatment, providing a better administration route. Sodium silybin sulfonate has incomparable advantages over silybin, and thus also has broad significance and great therapeutic value in clinical applications.

Description

A silymarin derivative, its preparation method and application Technical Field

[0001] This invention relates to a derivative of silymarin, its preparation method and application, belonging to the field of chemical technology. Background Technology

[0002] Silymarin is a flavonoid lignan compound extracted and refined from the fruit of the milk thistle (Silybum marianum), a plant in the Asteraceae family. Its main components include four isomers: silybin, isosilybin, silybinine, and silybinine. Silybin has the highest content and strongest hepatoprotective activity, showing good efficacy against acute and chronic hepatitis, cirrhosis, and liver damage caused by metabolic poisoning, making it a natural hepatoprotective drug. Modern research has found that silybin is a drug with multiple functions and targets. Its pharmacological effects are not only reflected in its most widely studied hepatoprotective effect, but also include various other pharmacological activities such as lowering blood lipids, anti-oxidation, preventing diabetes, protecting the myocardium, inhibiting platelet aggregation, and anti-tumor effects. Silybin is composed of two diastereomers, silybin A and silybin B, mixed in equal proportions. Its English name is Silybin, and its Chinese name is 2,3-dihydro-3-(4-hydroxy-3-methoxyphenyl)-2-hydroxymethyl-6-(3,5,7-trihydroxy-4-oxobenzopyran-2-yl)benzodioxane. Its CAS number is 22888-70-6, its molecular formula is C25H22O10, its molecular weight is 482.436, its melting point is 164-174℃, and its density is 1.527 g / cm3. Pure silybin is a white crystalline powder, odorless, with a slightly bitter taste, and hygroscopic. It is soluble in acetone, ethyl acetate, methanol, and ethanol, slightly soluble in chloroform, and almost insoluble in water. Its structural formula is shown in formula (I). Formula (I).

[0003] Relevant literature indicates that silymarin is a safe hepatitis treatment drug with a long history of use. Numerous studies have been conducted on its structural modification and structure-activity relationship (SAR) analysis, but ideal derivatives have yet to be obtained. This is mainly because most derivatives improve solubility by altering one or more hydroxyl groups in silymarin, without introducing synergistic groups into the flavonoid core skeleton. Preliminary SAR studies on the hepatoprotective effect of silymarin show that the presence of the flavonoid core, benzodioxane structure, and multiple hydroxyl groups in its molecule all contribute to enhanced hepatoprotective activity. The hydroxyl group at position 3 and the hydroxymethyl group at position 23 are essential for maintaining activity; derivatives of these hydroxyl groups reduce the hepatoprotective effect of silymarin. Complex natural drugs with poor water solubility have low bioavailability, making it difficult to fully realize their pharmacological activity, which greatly limits their use. The sodium sulfonate group (-SO3Na) is a strongly hydrophilic group. Introducing a hydrophilic group into the molecule of a poorly soluble compound can greatly increase its water solubility, which is an effective method to improve its bioavailability and efficacy. There are successful examples, such as the preparation of the cardiovascular drug tanshinone IIA into tanshinone IIA sodium sulfonate injection. Although silymarin has pharmacological activities such as scavenging free radicals, resisting lipid peroxidation, protecting hepatocyte membranes, promoting the synthesis of DNA and structural proteins in damaged hepatocytes, and anti-fibrosis, and has good efficacy for acute and chronic hepatitis, metabolic toxic liver injury, and cirrhosis, its low bioavailability due to its insolubility in water greatly reduces its clinical efficacy. Currently, hepatoprotective drugs with silymarin as the main drug are all administered orally in capsules and tablets. Some literature uses silymarin with solubilizers to make injections, or silymarin and meglumine to form a salt and then make a lyophilized powder for injection. However, even so, due to unstable absorption, the bioavailability is still poor and it is difficult to exert its pharmacological activity. At present, no injection with silymarin as the main active ingredient has been approved for marketing and clinical use. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a silymarin derivative, its preparation method, and its application. By introducing a hydrophilic group into the molecule of a poorly soluble compound, the water solubility is greatly increased, thereby improving its bioavailability and therapeutic effect.

[0005] This invention solves the technical problem through the following technical solution: First, it proposes a silybin derivative, wherein the silybin derivative is a sodium silybin sulfonate or a sodium silybin derivative sulfonate, with the following general formula:

[0006] Equation (II)

[0007] In the formula, R1-R5 can be at least one of hydrogen, alkyl, alkylyl, phenyl, or benzoyl. The silymarin derivative of this invention, sodium silymarin sulfonate, is a novel compound synthesized for the first time. Its chemical name is sodium 2,3-dihydro-3-(4-hydroxy-3-methoxyphenyl)-2-hydroxymethyl-6-(3,5,7-trihydroxy-4-oxobenzopyran-2-yl)benzodioxane-8-sulfonate. Molecular formula: C25H21NaO13S, molecular weight: 584.49, melting point: 173-176℃. It is readily soluble in water and methanol, soluble in ethanol, and slightly soluble in isopropanol. It is a white crystalline powder, odorless, with a slightly bitter taste, and hygroscopic. The structure of the product was confirmed by mass spectrometry, nuclear magnetic resonance, infrared spectroscopy, and ultraviolet spectroscopy: Chemical structural formula of sodium silymarin sulfonate (III):

[0008]

[0009] Equation (III).

[0010] Silymarin is a compound with alternating benzene and heterocyclic rings. Its chemical structure (I) shows three benzene rings and two heterocyclic rings, along with five hydroxyl groups. These can be classified into phenolic hydroxyl, secondary hydroxyl, and primary hydroxyl groups based on their positions. The secondary and primary hydroxyl groups exhibit strong reactivity, while the phenolic hydroxyl groups contribute to silymarin's weak acidity in aqueous solution. Silymarin is easily oxidized and relatively stable under acidic conditions, but its structure is destroyed by strong alkalis or heating, rendering it unstable. Due to its complex structure and numerous reactive sites, sulfonation to prepare the target product, sulfonate, is challenging. In particular, the 6th and 8th positions of the silymarin flavonoid nucleus benzene ring exhibit strong reactivity, with the 8th position showing slightly greater reactivity than the 6th. The target product is obtained through sulfonation at the 8th position of the flavonoid nucleus benzene ring. Silymarin is only soluble in acetone, ethyl acetate, methanol, and ethanol, exhibiting poor solubility in most organic solvents. This increases the difficulty of sulfonation, making the selection of suitable solvents and sulfonating agents, as well as the exploration of appropriate reaction conditions, extremely important.

[0011] Based on the above reasons, this invention further provides a method for preparing the above-mentioned sodium silybin sulfonate and sodium silybin derivative sulfonate. According to the reactivity characteristics of the 8-position of the benzene ring in the silybin flavonoid nucleus, a suitable sulfonating reagent and a special sulfonation technique are selected, and the reaction conditions are controlled to selectively carry out the sulfonation reaction at the 8-position of the benzene ring in the flavonoid nucleus, generating an 8-silybin sulfonic acid intermediate. This intermediate is then salted using a saturated sodium chloride aqueous solution, purified by water-soluble lower alcohol organic solvents, and obtained by vacuum or freeze-drying to obtain sodium 8-silybin sulfonate. The reaction equation is as follows:

[0012] The specific method includes the following steps.

[0013] Step 1: Extraction of silybin. Milk thistle fruit is pressed to remove oil, then pre-degreased with n-hexane, and then extracted with ethanol or ethyl acetate as the extraction solvent. Silybin is dissolved in anhydrous ethanol by heating, decolorized with activated carbon, and the filtrate is left to precipitate white crystals. Silybin is then recrystallized with ethyl acetate-methanol.

[0014] The second step is to prepare the 8-silybin sulfonic acid intermediate by performing a sulfonation reaction at the 8-position of the benzene ring of the silybin flavonoid core to generate a reaction mixture containing the 8-silybin sulfonic acid intermediate.

[0015] The third step, salt formation and purification, involves adding a saturated sodium chloride aqueous solution to the reaction mixture containing the silymarin sulfonic acid intermediate for quenching, separating the acetonitrile or dioxane solvent, concentrating under reduced pressure to remove most of the acetonitrile or dioxane solvent, and then adding a saturated sodium chloride aqueous solution for salt formation. After salt formation, the crude solid product is recrystallized multiple times with isopropanol or other water-soluble lower alcohol organic solvents. After purification to meet the purity requirements for injection, it is then vacuum-dried or freeze-dried to obtain sodium 8-silymarin sulfonic acid.

[0016] This invention further provides three sulfonation reaction methods.

[0017] In the second step of the first method, the sulfonation reaction is carried out by adding 0.5-5 times the molar amount of aminosulfonic acid, 0.5-5 times the molar amount of sodium bisulfate monohydrate, 0.5-5 times the molar amount of concentrated sulfuric acid, and 0.5-5% of the molar amount of silybin in a solvent such as acetonitrile or dioxane, and 0.5-5% of the molar amount of 18-crown ether-6 phase transfer catalyst. After stirring and mixing at room temperature, silybin is added and stirring is continued until homogeneous. The temperature is then raised to 30-80°C and stirred for 3 hours. The reaction process is monitored by TLC until the starting material disappears and the reaction is stopped to obtain 8-silybin sulfonic acid intermediate.

[0018] In the second method, the sulfonation reaction is carried out in a solvent such as acetonitrile or dioxane, which is 5-50 times the weight of silymarin. Phosphorus pentoxide is added, which is 0.5-5 times the molar amount of silymarin. Concentrated sulfuric acid is added dropwise while stirring. After stirring at room temperature for 30 minutes, silymarin is slowly added. The reaction solution is stirred and reacted at 30-80°C for 3 hours. The reaction process is monitored by TLC until the starting material disappears and then the reaction is stopped to obtain 8-silymarin sulfonic acid intermediate.

[0019] In the third method, in the second step, the sulfonation reaction involves adding 0.5-5 times the molar amount of sodium sulfate, 0.5-5 times the molar amount of concentrated sulfuric acid, and 0.5-5 times the molar amount of silymarin to a solvent such as acetonitrile or dioxane (5-50 times the weight of silymarin). After stirring and mixing at room temperature, silymarin is added and stirring is continued until homogeneous. The reaction is then carried out at 30-80°C for about 3 hours. The reaction process is monitored by TLC until the starting material disappears, at which point the reaction is stopped to obtain the 8-silymarin sulfonic acid intermediate.

[0020] This invention, through extensive experimental exploration and screening, determines the selection of reagents in the sulfonation reaction:

[0021] Commonly used sulfonating agents include concentrated sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, sulfur trioxide, sulfur trioxide-pyridine complexes, and aminosulfonic acid. Currently, concentrated sulfuric acid and fuming sulfuric acid are the most widely used and technologically mature sulfonating agents in industry, but they generate a large amount of waste acid, resulting in high post-treatment costs. Sulfur trioxide and chlorosulfonic acid are chemically reactive; when used in sulfonation reactions, they require small amounts, produce good sulfonation effects, and generate less waste acid, but the reactions are more difficult to control and produce more side reactions. Aminosulfonic acid (NH₂SO₃H) is a non-volatile, odorless, and non-toxic solid strong acid. It appears as white crystals, is chemically stable in dry environments, can be stored for a long time, and is easy to transport.

[0022] One of the following solvents was selected: dimethylformamide (DMF), dimethyl sulfoxide (DMSO), tetrahydrofuran, pyridine, dioxane, and acetonitrile. Sulfonating agents included concentrated sulfuric acid in combination with acetic anhydride and sodium sulfate, anhydrous phosphorus pentoxide in combination with concentrated sulfuric acid, and aminosulfonic acid in combination with concentrated sulfuric acid and sodium bisulfate. It was found that these three sulfonating agents showed strong selectivity for the sulfonation reaction of silybin, all yielding high yields and purity of 8-silybin sodium sulfonate.

[0023] Dimethylformamide and dimethyl sulfoxide are difficult to remove residual solvents from, while tetrahydrofuran and pyridine are highly toxic. Acetonitrile or dioxane are preferred solvents, and aminosulfonic acid is preferred as the sulfonating agent. Aminosulfonic acid has many advantages as a sulfonating agent: high reaction selectivity, high product purity, and low waste generation during the reaction process. Aminosulfonic acid has relatively mild chemical properties, similar to sulfur trioxide tertiary amine complexes. Its sulfonation mechanism may involve aminosulfonic acid undergoing some transformation to release sulfur trioxide, which then acts on the reactants for sulfonation. However, the sulfonation reaction of aminosulfonic acid has weak reactivity and is a heterogeneous solid-liquid reaction, requiring vigorous stirring and resulting in low reactant conversion rates. This invention is the first to discover that adding a phase transfer catalyst can accelerate the reaction rate and make the reaction more complete. The phase transfer catalyst includes, but is not limited to, one or more of aza-15-crown ether-5, 15-crown ether-5, 18-crown ether-6, 4-carbonate benzo-15-crown ether-5, and aza-18-crown ether-6. Adding sodium bisulfate can enhance the activity of aminosulfonic acid and increase the product yield.

[0024] In the third step of the above preparation method, the water-soluble organic solvent is a lower alcohol or acetone; the lower alcohol is methanol, ethanol, propanol or isopropanol.

[0025] The present invention further provides the application of silybin derivatives, including their use in the preparation of pharmaceutical formulations for treating liver diseases.

[0026] The dosage form of the preparation is an injection or an oral preparation, and the oral preparation is a capsule, tablet, granule, or oral solution.

[0027] The method for preparing sodium silybin sulfonate and the technical ideas for preparing water-soluble sodium sulfonate provided by this invention are also applicable to flavonoid lignan compounds (general chemical formula IV) contained in milk thistle, such as isosilybin, silybinine, and silybinine.

[0028]

[0029] Formula (IV)

[0030] It was prepared into a water-soluble sodium sulfonate derivative, and the reaction equation is as follows:

[0031]

[0032] This invention introduces a hydrophilic sodium sulfonate group into silybin, sulfonating silybin to produce highly water-soluble sodium silybin sulfonate. This process, involving only the sulfonation of silybin to prepare a highly water-soluble sodium sulfonate salt, significantly improves its bioavailability without altering the active functional groups and core structure of silybin that contribute to its pharmacological activity. This enhanced solubility in water improves the pharmacokinetic characteristics of silybin, increasing its affinity and bioactivity. The resulting formulation can be made into an injection for clinical use. Sodium silybin sulfonate can also be formulated into oral preparations such as capsules, tablets, granules, and oral solutions. Its pharmacological effects and therapeutic efficacy for liver diseases will be significantly superior to those of natural silybin. Its beneficial effect is providing a superior route of administration, offering advantages unmatched by silybin itself, and will have broad significance and immense therapeutic value in clinical applications. Attached Figure Description

[0033] Figure 1 shows the MS spectrum of sodium silymarin sulfonate.

[0034] Figure 2 shows the 1H NMR spectrum of sodium silymarin sulfonate.

[0035] Figure 3 shows the 13C NMR spectrum of sodium silymarin sulfonate.

[0036] Figure 4 shows the IR (KBr) spectrum of sodium silymarin sulfonate.

[0037] Figure 5 shows the UV spectrum of sodium silymarin sulfonate. Detailed Implementation

[0038] Example 1

[0039] In this embodiment, sodium 8-silymarin sulfonate was prepared by the following method: In a reaction flask, 80g of aminosulfonic acid, 60g of sodium bisulfate monohydrate, 1000ml of acetonitrile solvent, 80ml of concentrated sulfuric acid, and 5g of 18-crown ether-6 phase transfer catalyst were added. After stirring at room temperature for 30 minutes, 200g of silymarin was slowly added and stirred until homogeneous. The temperature was raised to 50-60℃ and the reaction was stirred for about 3 hours. The reaction was monitored by TLC until the starting material disappeared and then the reaction was stopped.

[0040] After the reaction was completed, a saturated sodium chloride aqueous solution was added for quenching, and the acetonitrile solvent was separated. Most of the acetonitrile solvent was removed by vacuum concentration. Then, a saturated sodium chloride aqueous solution was added to form a salt. The crude solid was recrystallized multiple times with isopropanol. After purification and drying, 162g of purified sodium 8-silymarin sulfonate was obtained, with a yield of 81%.

[0041] Example 2

[0042] In this embodiment, sodium 8-silymarin sulfonate was prepared by the following method: In a reaction flask, 100g of aminosulfonic acid, 40g of sodium bisulfate monohydrate, 1000ml of acetonitrile solvent, 50ml of concentrated sulfuric acid, and 5g of 18-crown ether-6 phase transfer catalyst were added. After stirring at room temperature for 30 minutes, 200g of silymarin was slowly added and stirred until homogeneous. The temperature was raised to 60-70℃ and the reaction was stirred for about 3 hours. The reaction process was monitored by TLC until the starting material disappeared and then the reaction was stopped.

[0043] After the reaction was completed, a saturated sodium chloride aqueous solution was added for quenching, and the acetonitrile solvent was separated. Most of the acetonitrile solvent was removed by vacuum concentration. Then, a saturated sodium chloride aqueous solution was added to form a salt. The crude solid was recrystallized multiple times with isopropanol. After purification and drying, 168g of purified sodium 8-silymarin sulfonate was obtained, with a yield of 84%.

[0044] Example 3

[0045] In this embodiment, sodium 8-silymarin sulfonate was prepared by the following method: 100g of aminosulfonic acid, 60g of sodium bisulfate monohydrate, 1000ml of acetonitrile solvent, and 30ml of concentrated sulfuric acid were added to a reaction flask. After stirring at room temperature for 30 minutes, 200g of silymarin was slowly added and stirred until homogeneous. The temperature was raised to 70-80℃ and the reaction was stirred for about 3 hours. The reaction was monitored by TLC until the starting material disappeared and then the reaction was stopped.

[0046] After the reaction was completed, a saturated sodium chloride aqueous solution was added for quenching, and the acetonitrile solvent was separated. Most of the acetonitrile solvent was removed by vacuum concentration. Then, a saturated sodium chloride aqueous solution was added to form a salt. The crude solid was recrystallized multiple times with isopropanol. After purification and drying, 158g of purified sodium 8-silymarin sulfonate was obtained, with a yield of 79%.

[0047] Example 4

[0048] In this embodiment, sodium 8-silymarin sulfonate was prepared by the following method: In a reaction flask, 100g of aminosulfonic acid, 50g of sodium bisulfate monohydrate, 1000ml of dioxane solvent, 60ml of concentrated sulfuric acid, and 5g of 18-crown ether-6 phase transfer catalyst were added. After stirring at room temperature for 30 minutes, 200g of silymarin was slowly added and stirred until homogeneous. The temperature was raised to 70-80℃ and the reaction was stirred for about 2 hours. The reaction was monitored by TLC until the starting material disappeared and then the reaction was stopped.

[0049] After the reaction was completed, a saturated sodium chloride aqueous solution was added for quenching, and the dioxane solvent was separated. The dioxane solvent was removed by vacuum concentration. Then, a saturated sodium chloride aqueous solution was added to form a salt. The crude solid was recrystallized multiple times with isopropanol. After purification and drying, 160g of purified sodium 8-silymarin sulfonate was obtained, with a yield of 80%.

[0050] Example 5

[0051] In this embodiment, sodium 8-silymarin sulfonate was prepared by the following method: 60g of aminosulfonic acid, 80g of sodium bisulfate monohydrate, 1000ml of dioxane solvent, 70ml of concentrated sulfuric acid, and 5g of 18-crown ether-6 phase transfer catalyst were added to a reaction flask. After stirring at room temperature for 30 minutes, 200g of silymarin was slowly added and stirred until homogeneous. The temperature was raised to 60-70℃ and the reaction was stirred for about 2 hours. The reaction was monitored by TLC until the starting material disappeared and then the reaction was stopped.

[0052] After the reaction was completed, a saturated sodium chloride aqueous solution was added for quenching, and the dioxane solvent was separated. The dioxane solvent was removed by vacuum concentration. Then, a saturated sodium chloride aqueous solution was added to form a salt. The crude solid was recrystallized multiple times with isopropanol. After purification and drying, 156g of purified sodium 8-silymarin sulfonate was obtained, with a yield of 78%.

[0053] Example 6

[0054] In this embodiment, sodium 8-silymarin sulfonate was prepared according to the following method: 60g of phosphorus pentoxide and 1000ml of acetonitrile solvent were added to a reaction flask, and 30ml of concentrated sulfuric acid was added dropwise while stirring. After stirring at room temperature for 30 minutes, 100g of silymarin was slowly added, and the reaction solution was stirred continuously. The reaction was carried out at 40-50℃ for about 3 hours. The reaction process was monitored by TLC until the starting material disappeared and then the reaction was stopped.

[0055] After the reaction was completed, a saturated sodium chloride aqueous solution was added for quenching, and the acetonitrile solvent was separated. Most of the acetonitrile solvent was removed by vacuum concentration. Then, a saturated sodium chloride aqueous solution was added to form a salt. The crude solid was recrystallized multiple times with isopropanol. After purification and drying, 73g of purified sodium 8-fenitin disulfonate was obtained, with a yield of 73%.

[0056] Example 7

[0057] In this embodiment, sodium 8-silymarin sulfonate was prepared by the following method: 50g of phosphorus pentoxide and 1000ml of acetonitrile solvent were added to a reaction flask, and 50ml of concentrated sulfuric acid was added dropwise while stirring. After stirring at room temperature for 30 minutes, 100g of silymarin was slowly added, and the reaction solution was stirred continuously. The reaction was carried out at 40-50℃ for about 3 hours. The reaction process was monitored by TLC until the starting material disappeared and the reaction was stopped.

[0058] After the reaction was completed, a saturated sodium chloride aqueous solution was added for quenching, and the acetonitrile solvent was separated. The solvent was concentrated under reduced pressure to remove most of the acetonitrile solvent. Then, a saturated sodium chloride aqueous solution was added to form a salt. The crude solid was recrystallized multiple times with isopropanol. After purification and drying, 75g of purified sodium 8-fenitin disulfonate was obtained, with a yield of 75%.

[0059] Example 8

[0060] In this embodiment, sodium 8-silymarin sulfonate was prepared by the following method: 1000 ml of acetonitrile solvent, 60 g of anhydrous sodium sulfate, 15 ml of concentrated sulfuric acid, and 50 ml of acetic anhydride were added to a reaction flask. After stirring at room temperature for 30 minutes, 100 g of silymarin was slowly added and stirred until homogeneous. The temperature was raised to 40-50°C and the reaction was stirred for about 3 hours. The reaction was monitored by TLC until the starting material disappeared and then the reaction was stopped.

[0061] After the reaction was completed, a saturated sodium chloride aqueous solution was added for quenching, and the acetonitrile solvent was separated. Most of the acetonitrile solvent was removed by vacuum concentration. Then, a saturated sodium chloride aqueous solution was added to form a salt. The crude solid was recrystallized multiple times with isopropanol. After purification and drying, 60g of purified sodium 8-silymarin sulfonate was obtained, with a yield of 60%.

[0062] Example 9

[0063] In this embodiment, sodium 8-silymarin sulfonate was prepared by the following method: 30g of aminosulfonic acid, 20g of sodium bisulfate monohydrate, 400ml of acetonitrile solvent, and 50g of silymarin were added to a reaction flask. After stirring at room temperature for 30 minutes, 20ml of concentrated sulfuric acid was slowly added dropwise and stirred until homogeneous. The temperature was raised to 60-65℃ and the reaction was stirred for about 3 hours. The reaction was monitored by TLC until the starting material disappeared and then the reaction was stopped.

[0064] After the reaction was completed, a saturated sodium chloride aqueous solution was added for quenching, and the acetonitrile solvent was separated. Most of the acetonitrile solvent was removed by vacuum concentration. Then, a saturated sodium chloride aqueous solution was added to form a salt. The crude solid was recrystallized multiple times with isopropanol. After purification and drying, 36g of purified sodium 8-silymarin sulfonate was obtained, with a yield of 72%.

[0065] Example 10

[0066] In this embodiment, sodium 8-silymarin sulfonate was prepared by the following method: 25g of aminosulfonic acid, 300ml of acetonitrile solvent, and 50g of silymarin were added to a reaction flask. After stirring at room temperature for 30 minutes, 25ml of concentrated sulfuric acid was slowly added dropwise and stirred until homogeneous. The temperature was raised to 40-50℃ and the reaction was stirred for about 3 hours. The reaction was monitored by TLC until the starting material disappeared and then the reaction was stopped.

[0067] After the reaction was completed, a saturated sodium chloride aqueous solution was added for quenching, and the acetonitrile solvent was separated. Most of the acetonitrile solvent was removed by vacuum concentration. Then, a saturated sodium chloride aqueous solution was added to form a salt. The crude solid was recrystallized multiple times with isopropanol. After purification and drying, 30g of purified sodium 8-silymarin sulfonate was obtained, with a yield of 60%.

[0068] Example 11

[0069] In this embodiment, sodium 8-silymarin sulfonate was prepared by the following method: 20g aminosulfonic acid, 20g sodium bisulfate monohydrate, 300ml dioxane solvent, and 50g silymarin were added to a reaction flask. After stirring at room temperature for 30 minutes, 20ml concentrated sulfuric acid was slowly added dropwise and stirred until homogeneous. The temperature was raised to 60-70℃ and the reaction was stirred for about 3 hours. The reaction was monitored by TLC until the starting material disappeared and then the reaction was stopped.

[0070] After the reaction was completed, a saturated sodium chloride aqueous solution was added for quenching, and the dioxane solvent was separated. The dioxane solvent was removed by vacuum concentration. Then, a saturated sodium chloride aqueous solution was added to form a salt. The crude solid was recrystallized multiple times with isopropanol. After purification and drying, 35g of purified sodium 8-silymarin sulfonate was obtained, with a yield of 70%.

[0071] Example 12

[0072] In this embodiment, sodium 8-silymarin sulfonate was prepared by the following method: 30g of aminosulfonic acid, 1g of 18-crown ether-6 phase transfer catalyst, 300ml of dioxane solvent, and 50g of silymarin were added to a reaction flask. After stirring at room temperature for 30 minutes, 20ml of concentrated sulfuric acid was slowly added dropwise and stirred until homogeneous. The temperature was raised to 50-60℃ and the reaction was stirred for about 3 hours. The reaction was monitored by TLC until the starting material disappeared and then the reaction was stopped.

[0073] After the reaction was completed, a saturated sodium chloride aqueous solution was added for quenching, and the dioxane solvent was separated. The dioxane solvent was removed by vacuum concentration. Then, a saturated sodium chloride aqueous solution was added to form a salt. The crude solid was recrystallized multiple times with isopropanol. After purification and drying, 32g of purified sodium 8-silymarin sulfonate was obtained, with a yield of 64%.

[0074] Example 13

[0075] In this embodiment, sodium 8-silymarin sulfonate was prepared by the following method: In a reaction flask, 30g of aminosulfonic acid, 20g of sodium bisulfate monohydrate, 1g of 18-crown ether-6 phase transfer catalyst, 500ml of tetrahydrofuran solvent, and 50g of silymarin were added. After stirring at room temperature for 30 minutes, 20ml of concentrated sulfuric acid was slowly added dropwise and stirred until homogeneous. The temperature was raised to 50-60℃ and the reaction was stirred for about 3 hours. The reaction was monitored by TLC until the starting material disappeared and then the reaction was stopped.

[0076] After the reaction was completed, a saturated sodium chloride aqueous solution was added for quenching, and the tetrahydrofuran solvent was separated. Most of the tetrahydrofuran solvent was removed by vacuum concentration. Then, a saturated sodium chloride aqueous solution was added to form a salt. The crude solid was recrystallized multiple times with isopropanol. After purification and drying, 38g of purified sodium 8-silymarin sulfonate was obtained, with a yield of 76%.

[0077] Example 14

[0078] In this embodiment, sodium 8-silymarin sulfonate was prepared by the following method: 45g of sulfur trioxide pyridine complex, 1g of 18-crown ether-6 phase transfer catalyst, 500ml of pyridine solvent, and 50g of silymarin were added to a reaction flask. After stirring at room temperature for 30 minutes, 10ml of concentrated sulfuric acid was slowly added dropwise and stirred until homogeneous. The temperature was raised to 70-80℃ and the reaction was stirred for about 3 hours. The reaction was monitored by TLC until the starting material disappeared and then the reaction was stopped.

[0079] After the reaction was completed, a saturated sodium chloride aqueous solution was added for quenching, the pyridine solvent was separated, most of the pyridine solvent was removed by vacuum concentration, and then a saturated sodium chloride aqueous solution was added for salt formation. The crude solid was recrystallized multiple times with isopropanol, and after purification and drying, 30g of purified sodium 8-silymarin sulfonate was obtained, with a yield of 60%.

[0080] Example 15

[0081] In this embodiment, sodium 8-silymarin sulfonate was prepared by the following method: In a reaction flask, 30g of aminosulfonic acid, 20g of sodium bisulfate monohydrate, 1g of 18-crown ether-6 phase transfer catalyst, 200ml of dimethylformamide solvent, and 50g of silymarin were added. After stirring at room temperature for 30 minutes, 20ml of concentrated sulfuric acid was slowly added dropwise and stirred until homogeneous. The temperature was raised to 70-80℃ and the reaction was stirred for about 3 hours. The reaction was monitored by TLC until the starting material disappeared and then the reaction was stopped.

[0082] After the reaction was completed, a saturated sodium chloride aqueous solution was added for quenching, and the dimethylformamide solvent was separated. Most of the dimethylformamide solvent was removed by vacuum concentration. Then, a saturated sodium chloride aqueous solution was added to form a salt. The crude solid was recrystallized multiple times with isopropanol. After purification and drying, 41g of purified sodium 8-silymarin sulfonate was obtained, with a yield of 82%.

[0083] Example 16

[0084] In this embodiment, sodium 8-silymarin sulfonate was prepared by the following method: 10g of silymarin and 70ml of acetonitrile solvent were added to a reaction flask. After stirring at room temperature for 10 minutes, a solution prepared by dissolving 10ml of chlorosulfonic acid in 30ml of acetonitrile solvent was slowly added dropwise. After the addition was complete, the reaction was continued to be stirred at room temperature for about 2 hours. The reaction process was monitored by TLC until the starting material disappeared and then the reaction was stopped.

[0085] After the reaction was completed, a saturated sodium chloride aqueous solution was added for quenching, and the acetonitrile solvent was separated. Most of the acetonitrile solvent was removed by vacuum concentration. Then, a saturated sodium chloride aqueous solution was added to form a salt. The crude solid was recrystallized multiple times with isopropanol. After purification and drying, 7.5 g of purified sodium 8-silymarin sulfonate was obtained, with a yield of 75%.

[0086] The obtained product was structurally confirmed by mass spectrometry (Figure 1), nuclear magnetic resonance (Figures 2 and 3), infrared spectroscopy (Figure 4), and ultraviolet spectroscopy (Figure 5, characteristic peaks appear at wavelengths of 203 nm and 286 nm), confirming the chemical structure (III) of sodium silybin sulfonate. According to the solubility determination method in the Chinese Pharmacopoeia, 650 mg of sodium silybin sulfonate can be dissolved in 1 ml of purified water at room temperature, indicating it is readily soluble in water.

[0087] In addition to the above-described embodiments, the present invention may have other implementations. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

Claims

1. A silymarin derivative, characterized in that, The silybin derivative is a sodium silybin sulfonate or a sodium silybin derivative sulfonate, with the following general formula: Formula (II), in which R1-R5 is at least one of hydrogen, alkyl, alkanoyl, phenyl, and benzoyl.

2. The silymarin derivative according to claim 1, characterized in that: The chemical structural formula of sodium silymarin sulfonate is as follows: Equation (III).

3. The method for preparing the silymarin derivative according to claim 1 or 2, characterized in that: The process involves sulfonating silymarin to produce silymarin sulfonic acid, followed by a salt formation reaction in a saturated sodium chloride aqueous solution. After separation and treatment to obtain crude sodium silymarin sulfonate, the product is purified by recrystallization with a water-soluble organic solvent and finally obtained by vacuum or freeze-drying.

4. The method for preparing the silymarin derivative according to claim 3, characterized in that: Includes the following steps, Step 1: Extracting silybin. After pressing and degreasing the milk thistle fruit, extract silybin, dissolve silybin, filter and decolorize. After white crystals precipitate from the filtrate, recrystallize to obtain silybin. The second step is to prepare the 8-silybin sulfonic acid intermediate by performing a sulfonation reaction at the 8-position of the benzene ring of the silybin flavonoid core to generate a reaction mixture containing the 8-silybin sulfonic acid intermediate. The third step, salt formation and purification, involves adding a saturated sodium chloride aqueous solution to the reaction mixture containing silymarin sulfonic acid intermediate for quenching, separating out solvents such as acetonitrile or dioxane, concentrating under reduced pressure to remove most of the acetonitrile or dioxane solvents, and then adding a saturated sodium chloride aqueous solution for salt formation. After salt formation, the crude solid product is recrystallized multiple times using a water-soluble organic solvent. After purification to meet the purity requirements for injection, sodium 8-silymarin sulfonic acid is obtained by vacuum or freeze drying.

5. The method for preparing the silymarin derivative according to claim 4, characterized in that: In the second step, the sulfonation reaction is carried out in a solvent such as acetonitrile or dioxane, which is 5-50 times the weight of silymarin. Then, 0.5-5 times the molar amount of aminosulfonic acid, 0.5-5 times the molar amount of sodium bisulfate monohydrate, 0.5-5 times the molar amount of concentrated sulfuric acid, and 0.5-5% of the weight of silymarin 18-crown ether-6 phase transfer catalyst are added. After stirring and mixing at room temperature, silymarin is added and stirring is continued until homogeneous. Then, the temperature is raised to 30-80°C and stirred for 3 hours. The reaction process is monitored by TLC until the starting material disappears and the reaction is stopped to obtain 8-silymarin sulfonic acid intermediate.

6. The method for preparing the silymarin derivative according to claim 4, characterized in that: In the second step, the sulfonation reaction is carried out by adding phosphorus pentoxide in a solvent such as acetonitrile or dioxane, which is 5-50 times the weight of silybin, and adding concentrated sulfuric acid, which is 0.5-5 times the molar weight of silybin, dropwise while stirring. After stirring at room temperature for 30 minutes, silybin is slowly added, and the reaction solution is stirred continuously. The reaction is carried out at 30-80°C for 3 hours. The reaction process is monitored by TLC until the starting material disappears, and then the reaction is stopped to obtain 8-silybin sulfonic acid intermediate.

7. The method for preparing the silymarin derivative according to claim 4, characterized in that: In the second step, the sulfonation reaction involves adding 0.5-5 times the molar amount of sodium sulfate, 0.5-5 times the molar amount of concentrated sulfuric acid, and 0.5-5 times the molar amount of silymarin to a solvent such as acetonitrile or dioxane (5-50 times the weight of silymarin). After stirring and mixing at room temperature, silymarin is added and stirring is continued until homogeneous. The reaction is then carried out at 30-80°C for about 3 hours. The reaction process is monitored by TLC until the starting material disappears, at which point the reaction is stopped to obtain the 8-silymarin sulfonic acid intermediate.

8. The method for preparing the silymarin derivative according to claim 4, characterized in that: In the third step, the water-soluble organic solvent is a lower alcohol or acetone; the lower alcohol is methanol, ethanol, propanol or isopropanol.

9. The use of the silymarin derivative according to claim 1 or 2, including its use in the preparation of pharmaceutical formulations for treating liver diseases.

10. The application of the silymarin derivative according to claim 9, characterized in that: The dosage form of the preparation is an injection or an oral preparation, and the oral preparation is a capsule, tablet, granule or oral solution.

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