Oxidized matrine-caffeic acid eutectic and preparation method thereof

Abstract

The invention discloses an oxymatrine-caffeic acid co-crystal and a preparation method thereof, and belongs to the technical field of natural product co-crystallization, the molecular formula of oxymatrine-caffeic acid is C15H25N2O2.C9H7O4. 3H2O, the crystal structure belongs to a monoclinic system, the preparation method of the oxymatrine-caffeic acid co-crystal comprises the following steps: respectively weighing oxymatrine and caffeic acid according to a molar ratio, and adding the oxymatrine and the caffeic acid into a reaction kettle; and mixing the two components, and placing the mixture in a glass container. And then, adding a proper amount of solvent into the container, filtering the obtained oxymatrine-caffeic acid mixed solution, standing, volatilizing and crystallizing to obtain the oxymatrine-caffeic acid eutectic. The oxymatrine-caffeic acid eutectic prepared by the invention can effectively improve the dissolution performance of an insoluble natural product caffeic acid and improve the bioavailability of the caffeic acid. The preparation method is simple and easy for industrial development and production, and has a good application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of natural product co-crystallization, and in particular to an oxymatrine-caffeic acid co-crystal and a preparation method thereof. Background Art

[0002] Caffeic acid (CAF), as a typical phenolic acid compound, has multiple biological activities such as antioxidant and antibacterial properties. However, the electron delocalization characteristics of its benzene ring-carboxylic acid skeleton lead to poor water solubility and chemical stability. Although the molecular flexibility of the acrylic acid side chain is conducive to adaptation to rigid alkaloids, its low water solubility (limited bioavailability) limits its application in the food and pharmaceutical industries.

[0003] Oxymatrine (OMT), a signature alkaloid from the Sophora flavescens plant, possesses a unique NO polar group within its structure, which imparts strong hydrophilicity (logP = -0.33). OMT exhibits anti-inflammatory and anticancer pharmacological activities, including the ability to modulate drug efflux. This dual "ligand-effect" property offers unique potential for OMT's application in natural product delivery systems.

[0004] Traditional methods of improving drug crystal forms (such as salt formation) are limited by the spatial electronic effects of phenolic acid compound substituents (hydroxyl, methoxy, etc.), which restricts the salt-forming ability. However, drug cocrystals, as a new type of crystal form, can combine active ingredients with cocrystal reagents through non-covalent bonds (hydrogen bonds, π-π conjugation, etc.), thereby improving the physical and chemical properties without changing the core structure of the drug. However, there is no effective solution for the cocrystal construction and performance optimization of OMT and CAF. Summary of the Invention

[0005] The present invention provides an oxymatrine-caffeic acid cocrystal and a method for preparing the same. The cocrystal combines phenolic acids with a naturally occurring product that is also biologically active and water-soluble. Oxymatrine (OMT), a signature alkaloid of the Sophora flavescens plant, is characterized by its unique NO polar group, which imparts strong hydrophilicity (logP = -0.33) and allows for supersaturated solubility at physiological pH, making it an ideal alkaline ligand. The resulting oxymatrine-caffeic acid cocrystal exhibits improved caffeic acid solubility, dissolution rate, and bioavailability compared to the caffeic acid raw material. Furthermore, oxymatrine exhibits multiple biological activities, resulting in a synergistic effect.

[0006] To achieve the above object, the present invention provides an oxymatrine-caffeic acid co-crystal, wherein the molecular formula of the oxymatrine-caffeic acid co-crystal is C 15 H 25 N2O2·C9H7O4·3H2O, the crystal structure belongs to the monoclinic system, the space group is P21, and the unit cell parameters are α=90°,β=113.516(2)°,γ=90°,unit cell volume The minimum number of asymmetric units in the unit cell is Z = 2, and the crystal density is 1.333 g / cm 3 ;

[0007] The oxymatrine-caffeic acid co-crystal has characteristic diffraction peaks at 9.64°, 12.02°, 12.92°, 14.7°, 15.48°, 18.32°, 18.94°, 20.76°, 22.3°, 23.5°, 23.88°, 25°, 26.28° and 28.64° in a powder X-ray diffraction pattern measured using Cu-Kβ radiation after grinding;

[0008] The infrared spectrum of the oxymatrine-caffeic acid co-crystal measured using potassium bromide tablets is at 3540 cm -1 , 3355cm -1 , 2942cm -1 , 2713cm -1 , 1918cm -1 , 1610cm -1 , 1521cm -1 , 1411cm -1 , 1382cm -1 , 1270cm -1 , 1220cm -1 , 1162cm -1 , 979cm -1 , 860cm -1 , 717cm -1 , 588cm -1 There is a characteristic absorption peak at the infrared spectrum, and the allowable deviation of the characteristic peak is ±2cm -1 ;

[0009] The differential scanning calorimetry curve of the oxymatrine-caffeic acid co-crystal shows an endothermic peak in the range of 60-110°C and a melting point of 151°C;

[0010] The thermogravimetric analysis curve of the oxymatrine-caffeic acid co-crystal shows that the co-crystal continuously loses crystal water at 25-108°C. After completely losing the crystal water, the structure remains stable in the range of 108-120°C.

[0011] The oxymatrine-caffeic acid eutectic is a crystalline powder.

[0012] The preparation method of oxymatrine-caffeic acid co-crystal comprises the following steps: weighing oxymatrine and caffeic acid respectively according to a molar ratio, placing the weighed oxymatrine and caffeic acid into a glass container and mixing them to obtain a mixed raw material powder, adding a solvent into the glass container, continuously stirring, heating the glass container in a water bath to dissolve the mixed raw materials to obtain a clear solution, cooling and filtering, standing and volatilizing, and obtaining light yellow block crystals, i.e., oxymatrine-caffeic acid co-crystals, after the solvent slowly evaporates.

[0013] Preferably, in the method for preparing the above-mentioned oxymatrine-caffeic acid cocrystal, the molar ratio of oxymatrine to caffeic acid is 0.5-2:1.

[0014] Preferably, in the above-mentioned method for preparing oxymatrine-caffeic acid cocrystal, the solvents used include a first solvent and a second solvent, the first solvent is distilled water, and the second solvent includes one or more of methanol, ethanol, isopropanol, acetonitrile and acetone.

[0015] Preferably, in the above-mentioned method for preparing oxymatrine-caffeic acid co-crystal, the volume ratio of the first solvent to the second solvent is 1:5-10.

[0016] Preferably, in the above-mentioned method for preparing oxymatrine-caffeic acid co-crystal, the solid-liquid ratio of the mixed raw material and the mixed solvent is 3-15 mg:1 mL.

[0017] Preferably, in the above-mentioned method for preparing oxymatrine-caffeic acid cocrystal, the water bath heating temperature is 10-60° C., and the stirring time is 0.5-1 h.

[0018] Preferably, in the preparation method of the above-mentioned oxymatrine-caffeic acid co-crystal, the standing volatilization temperature is 10-60° C. and the time is 1-30 days.

[0019] The application of the oxymatrine-caffeic acid co-crystal in anti-inflammatory, antibacterial drugs or food additives.

[0020] Therefore, the above-mentioned oxymatrine-caffeic acid co-crystal and preparation method thereof of the present invention have the following beneficial effects:

[0021] (1) By oxidizing matrine (strongly hydrophilic) and forming a cocrystal with caffeic acid, the polar groups and non-covalent bonds of the two are utilized to break through the bottleneck of poor water solubility of caffeic acid, significantly improve its solubility in aqueous environment, and thus improve its bioavailability.

[0022] (2) The NO polar group of oxymatrine and the acrylic acid side chain of caffeic acid form a cocrystal through topological adaptation, which not only retains their respective anti-inflammatory, antibacterial, and antiviral biological activities, but is also likely to produce a synergistic effect through intermolecular interactions and enhance drug efficacy. The property of oxymatrine to inhibit drug efflux can assist caffeic acid in exerting its effect.

[0023] (3) The crystalline powder morphology and specific physical and chemical properties of the cocrystal provide a basis for its stable application in pharmaceutical preparations (such as oral solid preparations, sustained-release systems) and food additives, solving the formulation development problem caused by the poor solubility of caffeic acid.

[0024] (4) The preparation method adopts a mild solvent evaporation method. By regulating the molar ratio, solvent composition and crystallization conditions, the controllable synthesis of cocrystals is achieved. The process is simple, low-cost and suitable for large-scale production, opening up a better strategic path for the pharmaceutical and food additive fields.

[0025] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is the unit cell stacking diagram of oxymatrine-caffeic acid cocrystal;

[0027] Figure 2 are powder X-ray diffraction patterns of oxymatrine-caffeic acid cocrystal, oxymatrine and caffeic acid;

[0028] Figure 3 are differential scanning calorimetry (DSC) diagrams of oxymatrine-caffeic acid cocrystal, oxymatrine and caffeic acid;

[0029] Figure 4 The thermogravimetric analysis (TGA) diagrams of oxymatrine-caffeic acid cocrystal, oxymatrine and caffeic acid;

[0030] Figure 5 FTIR spectra of oxymatrine-caffeic acid cocrystal, oxymatrine and caffeic acid;

[0031] Figure 6 is the powder dissolution curve of oxymatrine-caffeic acid cocrystal and caffeic acid;

[0032] Figure 7 is the powder X-ray diffraction pattern of the residue of oxymatrine-caffeic acid co-crystal at different pH;

[0033] Figure 8 is the intrinsic dissolution rate (IDR) diagram of oxymatrine-caffeic acid cocrystal and caffeic acid;

[0034] Figure 9This is a graph showing the short-term stability of oxymatrine-caffeic acid co-crystal under specific conditions;

[0035] Figure 10 Figure 2 is the plasma concentration-time curve of oxymatrine-caffeic acid cocrystal and caffeic acid in rats. DETAILED DESCRIPTION

[0036] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] The terms used in the embodiments of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The singular forms "a," "an," "the," and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, and unless the context clearly indicates otherwise, "a plurality" generally includes at least two.

[0038] It should also be noted that the terms "include," "comprises," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a product or device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such product or device. In the absence of further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the product or device comprising the element.

[0039] The present invention provides an oxymatrine-caffeic acid co-crystal, wherein the molecular formula of the oxymatrine-caffeic acid co-crystal is C 15 H 25 N2O2·C9H7O4·3H2O, the crystal structure belongs to the monoclinic system, the space group is P21, and the unit cell parameters are α=90°,β=113.516(2)°,γ=90°,unit cell volume The minimum number of asymmetric units in the unit cell is Z = 2, and the crystal density is 1.333 g / cm 3 ;

[0040] The powder X-ray diffraction pattern of the oxymatrine-caffeic acid co-crystal measured using Cu-Kβ radiation after grinding has characteristic diffraction peaks at 9.64°, 12.02°, 12.92°, 14.7°, 15.48°, 18.32°, 18.94°, 20.76°, 22.3°, 23.5°, 23.88°, 25°, 26.28° and 28.64° at 2θ angles expressed in degrees;

[0041] The infrared spectrum of oxymatrine-caffeic acid cocrystal measured using potassium bromide tablets is at 3540 cm -1 , 3355cm -1 , 2942cm -1 , 2713cm -1 , 1918cm -1 , 1610cm -1 , 1521cm -1 , 1411cm -1 , 1382cm -1 , 1270cm -1 , 1220cm -1 , 1162cm -1 , 979cm -1 , 860cm -1 , 717cm -1 , 588cm -1 There is a characteristic absorption peak at the infrared spectrum, and the allowable deviation of the characteristic peak is ±2cm -1 ;

[0042] The differential scanning calorimetry curve of oxymatrine-caffeic acid cocrystal showed an endothermic peak in the range of 60-110°C, and a melting point at 151°C;

[0043] The thermogravimetric analysis curve of oxymatrine-caffeic acid cocrystal shows that it continuously loses crystal water at 25-108°C. After completely losing crystal water, the structure remains stable at 108-120°C.

[0044] Oxymatrine-caffeic acid co-crystals are crystalline powder.

[0045] The preparation method of oxymatrine-caffeic acid co-crystal comprises the following steps: weighing oxymatrine and caffeic acid respectively according to a molar ratio, placing the weighed oxymatrine and caffeic acid into a glass container and mixing them to obtain a mixed raw material powder, adding a solvent into the glass container, continuously stirring, heating the glass container in a water bath to dissolve the mixed raw materials to obtain a clear solution, cooling and filtering, standing and volatilizing, and obtaining light yellow block crystals, i.e., oxymatrine-caffeic acid co-crystals, after the solvent slowly evaporates.

[0046] To further optimize the above technical solution, the molar ratio of oxymatrine to caffeic acid is 0.5-2:1.

[0047] To further optimize the above technical solution, the solvents used include a first solvent and a second solvent, the first solvent is distilled water, and the second solvent includes one or more of methanol, ethanol, isopropanol, acetonitrile and acetone.

[0048] To further optimize the above technical solution, the volume ratio of the first solvent to the second solvent is 1:5-10.

[0049] To further optimize the above technical solution, the solid-liquid ratio of the mixed raw materials and the mixed solvent is 3-15 mg:1 mL.

[0050] To further optimize the above technical solution, the water bath heating temperature is 10-60°C and the stirring time is 0.5-1h.

[0051] In order to further optimize the above technical solution, the static volatilization temperature is 10-60°C and the time is 1-30 days.

[0052] Oxymatrine-caffeic acid co-crystals can be used in anti-inflammatory, antibacterial drugs or food additives.

[0053] In order to more clearly and in detail introduce the oxymatrine-caffeic acid co-crystal and the preparation method thereof provided by the embodiments of the present invention, they will be described below with reference to specific examples.

[0054] Example 1

[0055] Preparation of oxymatrine-caffeic acid cocrystals:

[0056] Weigh oxymatrine (0.2 mmol, 53 mg) and caffeic acid (0.1 mmol, 18 mg) separately, add 10 mL of a mixed solution of acetonitrile / water (volume ratio = 9.5:1), reflux with stirring at 40 ° C for 1 h, cool to room temperature, filter, let stand, and evaporate naturally in a glass tube to obtain yellow block crystals after 5 days.

[0057] Example 2

[0058] Preparation of oxymatrine-caffeic acid cocrystals:

[0059] Weigh oxymatrine (0.2 mmol, 53 mg) and caffeic acid (0.1 mmol, 18 mg) separately, add 7 mL of acetone / water (volume ratio = 8:1) mixed solution, reflux with stirring at 35 ° C for 1 h, cool to room temperature, filter, let stand, and evaporate naturally in a glass tube. After 4 days, yellow block crystals are obtained.

[0060] Example 3

[0061] Preparation of oxymatrine-caffeic acid cocrystals:

[0062] Weigh oxymatrine (0.1 mmol, 26.5 mg) and caffeic acid (0.1 mmol, 18 mg) separately, add 12 mL of ethanol / water (volume ratio = 5:1) mixed solution, reflux and stir at 50°C for 1 h, cool to room temperature, filter, let stand, and evaporate naturally in a glass tube to obtain yellow block crystals after 5 days.

[0063] Test Example 1

[0064] Single crystal X-ray diffraction of oxymatrine-caffeic acid cocrystal: Crystal data such as Figure 1 As shown in Figure 2, the basic structural unit of oxymatrine-caffeic acid cocrystal is formed by one oxymatrine molecule, one caffeic acid molecule and three water molecules. The molecular formula of oxymatrine-caffeic acid cocrystal is C 15 H 25 N2O2·C9H7O4·3H2O, the crystal structure belongs to the monoclinic system, the space group is P21, and the unit cell parameters are α=90°,β=113.516(2)°,γ=90°,unit cell volume The minimum number of asymmetric units in the unit cell is Z = 2, and the crystal density is 1.333 g / cm 3 , the specific single crystal X-ray diffraction data are shown in Table 1.

[0065] Table 1 Single crystal X-ray diffraction data of oxymatrine-caffeic acid cocrystal

[0066]

[0067]

[0068]

[0069] After grinding, oxymatrine-caffeic acid cocrystal, oxymatrine and caffeic acid were subjected to powder X-ray diffraction using Cu-Kβ radiation. The powder X-ray diffraction pattern is shown in FIG. Figure 2 As shown in the figure, the characteristic diffraction peaks of oxymatrine at 9.36°, 13.66°, and 17.22° disappeared from the diffraction pattern of the oxymatrine-caffeic acid cocrystal, and the characteristic diffraction peaks of caffeic acid at 14.06° and 17.38° also disappeared from the diffraction pattern of the oxymatrine-caffeic acid cocrystal. At the same time, the oxymatrine-caffeic acid cocrystal showed characteristic diffraction peaks at 9.64°, 18.32°, and 23.88° that were different from those of the two individual components.

[0070] The DSC results of oxymatrine-caffeic acid cocrystal, oxymatrine and caffeic acid are as follows Figure 3As shown in Figure 2, oxymatrine undergoes crystallization at 162°C, with a melting point of 211°C; caffeic acid has a melting point of 222°C. After salt crystal formation, the oxymatrine-caffeic acid cocrystal exhibits a broad endothermic peak in the 60-110°C range. This is due to the presence of three crystalline waters in the structure, with a melting point of 151°C, lower than the melting points of oxymatrine and caffeic acid.

[0071] The TGA results of oxymatrine-caffeic acid cocrystal, oxymatrine and caffeic acid are as follows Figure 4 As shown in Figure 2, oxymatrine and caffeic acid have relatively high thermal stability. At 108°C, three water molecules in the structure of oxymatrine-caffeic acid co-crystal have been lost (theoretical value 10.8%, actual value 10.5%).

[0072] The infrared spectra of oxymatrine-caffeic acid cocrystal, oxymatrine and caffeic acid are as follows Figure 5 In the structure of oxymatrine, 2937cm -1 -CH2- stretching vibration peak, 2285cm -1 is the stretching vibration peak of NO, 1608cm -1 is the stretching vibration peak of C=O; in the structure of caffeic acid, 3430cm -1 is the stretching vibration peak of -OH on carboxylic acid, 3230 cm -1 The stretching vibration peak of non-carboxylic acid -OH is 1650cm -1 is the stretching vibration peak of C=O, 1450cm -1 The non-benzene ring C=C stretching vibration peak. After the formation of oxymatrine-caffeic acid cocrystal, the -OH (containing water) on the carboxylic acid and non-carboxylic acid are blue-shifted to 3540 cm -1 and 3355cm -1 , NO red-shifted to 1918 cm -1 The C=O on the caffeic acid also red-shifts to 1610 cm due to the proton transfer of the carboxylic acid. -1 .

[0073] Test Example 2

[0074] The dissolution performance of oxymatrine-caffeic acid co-crystals was tested in buffer solutions at pH 1.2 and pH 6.8 at 37 ± 0.5 °C using high performance liquid chromatography.

[0075] Chromatographic separation was performed using a WondaSil C18-WR reverse phase column (4.6 mm*250 mm, 5 μm) with a mobile phase of methanol-0.32% acetic acid aqueous solution (40:60, v / v) at a flow rate of 0.8 mL min -1 , column temperature 30 °C, UV detection wavelength 320 nm, injection volume 10 μL.

[0076] Equilibrium solubility test

[0077] The equilibrium solubility of oxymatrine-caffeic acid cocrystals and caffeic acid (ground and passed through an 80-mesh sieve) was determined using the shake-flask method. Excess sample was weighed and added to a vial containing 10 mL of dissolution medium. The solution was allowed to equilibrate for 24 hours before being filtered through a 0.45 μm Nylon filter. The filtrate was then diluted with chromatographic methanol to a concentration within the linear range for HPLC analysis. Each experiment was performed in triplicate.

[0078] The results showed that the equilibrium solubility of caffeic acid in pH 1.2 and pH 6.8 buffers was 0.36 ± 0.06 mg mL -1 and 0.53 ± 0.05 mg mL -1 , while the equilibrium solubility of oxymatrine-caffeic acid cocrystals was 5.90±0.02 mg·mL -1 and 5.06 ± 0.04 mg mL -1 The oxymatrine-caffeic acid cocrystal provided by the present invention increases the solubility of caffeic acid in a simulated gastrointestinal fluid environment, which is beneficial to the absorption of caffeic acid in vivo.

[0079] Powder dissolution test

[0080] The dissolution curves of oxymatrine-caffeic acid cocrystals and caffeic acid (ground and passed through an 80-mesh sieve) were measured using a paddle method at 100 rpm.

[0081] Excess sample was weighed and added to a cuvette containing 250 mL of dissolution medium. 2 mL of sample was aspirated at 2, 5, 10, 20, 30, 45, 60, 120, 240, and 360 min, filtered through a Nylon filter (0.45 μm), and immediately supplemented with 2 mL of preheated blank dissolution medium to maintain a constant total volume. The filtrate was then diluted with chromatographic methanol to a concentration within the linear range for HPLC analysis. Each experiment was performed in triplicate.

[0082] The results are as follows Figure 6 As shown in the figure, the formation of oxymatrine-caffeic acid cocrystals at different pH values ​​significantly increased the powder dissolution rate, and the dissolution was faster under acidic conditions. Within a few hours after reaching the peak concentration, the concentration of oxymatrine-caffeic acid cocrystals at different pH values ​​did not change significantly. Figure 7 As shown, the remaining dissolution powder after the test was collected, and it was found that the morphology of the co-crystal powder X-ray diffraction pattern was similar to that of the original co-crystal, and the characteristic peaks were consistent with each other well, indicating that it was sufficiently stable in the tested dissolution medium.

[0083] Intrinsic dissolution rate test

[0084] Weigh 300 mg of oxymatrine-caffeic acid cocrystal and caffeic acid sample (ground and passed through 80 mesh sieve) and sieve at 35 kg·cm -2 The mixture was compressed into a circular mold under a pressure of 100 rpm for 1 minute. 2 mL of dissolution medium was drawn at 2, 5, 10, 15, 20, 30, and 45 minutes, filtered with a Nylon filter (0.45 μm), and immediately supplemented with 2 mL of preheated blank dissolution medium, keeping the total volume constant. Subsequently, the filtrate was diluted with chromatographic methanol to a concentration within the linear range for HPLC analysis. Each experiment was repeated three times.

[0085] The results are as follows Figure 8 As shown in the figure, the intrinsic dissolution rate of the cocrystal and caffeic acid changes with pH in a similar way to the powder dissolution, i.e., the higher the pH value, the higher the intrinsic dissolution rate of the cocrystal, while the lower the intrinsic dissolution rate of caffeic acid. In the buffers at pH 1.2 and pH 6.8, the intrinsic dissolution rates of caffeic acid were 0.082 ± 0.004 mg·min, respectively. -1 cm -2 and 0.108±0.005mg·min -1 cm -2 , while the intrinsic dissolution rates of oxymatrine-caffeic acid cocrystals were 0.667±0.031 mg·min -1 cm -2 and 0.504±0.022mg·min -1 cm -2 , which increased by 8.1 and 4.7 times, respectively, indicating that the formation of cocrystals can improve the dissolution behavior of insoluble caffeic acid.

[0086] Test Example 3

[0087] Stability characteristics of oxymatrine-caffeic acid cocrystals:

[0088] Two 30 mg portions of cocrystal powder were weighed. One portion was placed in a desiccator containing anhydrous silica gel at a relative humidity (RH) below 15%, and the other portion was placed in a humidity chamber (RH = 75%) controlled by a saturated NaCl solution at 25°C for one month. Powder X-ray diffraction patterns were recorded after the tests.

[0089] The results are as follows Figure 9 As shown, the characteristic peak positions and relative intensities of the co-crystal in a long-term dry or high-humidity environment are similar to those of the powder X-ray diffraction pattern of the original co-crystal, indicating that it has strong stability.

[0090] Test Example 4

[0091] In vivo pharmacokinetic test in rats

[0092] Chromatographic separation was performed using a WondaSil C18-WR column (4.6 mm*250 mm, 5 μm) with a mobile phase of methanol-0.5% acetic acid aqueous solution (46:54, v / v) at a flow rate of 0.8 mL min -1 The column temperature was 30°C, the UV detection wavelength was 320 nm, the injection volume was 10 μL, and m-hydroxycinnamic acid was selected as the internal standard. Linear regression was performed using different caffeic acid concentrations as the abscissa and the peak area ratio of caffeic acid to m-hydroxycinnamic acid as the ordinate.

[0093] Healthy Sprague-Dawley rats were randomly divided into two groups, each with five rats and labeled. The cocrystals and caffeic acid were evenly dispersed in a 0.5% CMC-Na solution and administered orally at a caffeic acid equivalent of 60 mg kg⁻¹. Immediately after gavage, timing was performed, and approximately 0.3 mL of blood was collected via orbital respiration at 4, 8, 12, 18, 30, 45, 60, 90, 120, and 240 minutes after administration. The blood samples were placed in heparin-soaked EP tubes, allowed to stand for 30 minutes, and centrifuged at 3000 rpm for 10 minutes. The supernatant was collected to obtain fresh rat plasma and stored at -20°C until further use. 100 μL of plasma was collected, 100 μL of acetonitrile was added, and then 100 μL of m-hydroxycinnamic acid solution (prepared in acetonitrile) was added. The mixture was vortexed for 90 seconds, centrifuged at 10,000 rpm for 10 minutes, and 10 μL of the supernatant was injected for analysis.

[0094] The results are as follows Figure 10 As shown in Table 2, the formation of cocrystals improves the absorption of caffeic acid in vivo. The main pharmacokinetic parameters calculated by PKSolver non-compartmental model are shown in Table 2. Compared with caffeic acid alone, the C max and AUC (0-∞) increased by 118% and 177% respectively, and t 1 / 2 The absorption time also becomes longer, indicating that the preparation of oxymatrine-caffeic acid cocrystal not only improves the absorption level of caffeic acid but also maintains a higher blood concentration for a longer time, which will be more conducive to the efficacy of caffeic acid.

[0095] Table 2 Main pharmacokinetic parameters of cocrystals and caffeic acid

[0096]

[0097]

[0098] Therefore, the present invention adopts the above-mentioned oxymatrine-caffeic acid co-crystal and its preparation method, forms a co-crystal by oxymatrine (strongly hydrophilic) and caffeic acid, and utilizes the polar groups and non-covalent bonds of the two to break through the bottleneck of poor water solubility of caffeic acid, significantly improve its solubility in aqueous environments, and thus improve its bioavailability.

[0099] The NO polar group of oxymatrine and the acrylic acid side chain of caffeic acid form a co-crystal through topological adaptation, which not only retains their respective anti-inflammatory, antibacterial, antiviral and other biological activities, but is also likely to produce a synergistic effect through intermolecular interactions and enhance the efficacy. The property of oxymatrine to inhibit drug efflux can assist caffeic acid in exerting its effect.

[0100] The cocrystal's crystalline powder morphology and specific physicochemical properties provide a foundation for its stable application in pharmaceutical formulations (such as oral solid dosage forms and sustained-release systems) and food additives, addressing the formulation development challenges associated with caffeic acid's poor solubility. The preparation method utilizes a mild solvent evaporation method. By manipulating the molar ratio, solvent composition, and crystallization conditions, the cocrystal's controllable synthesis is achieved. This simple, low-cost process is suitable for large-scale production and opens up a promising strategic path for the pharmaceutical and food additive sectors.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An oxymatrine-caffeic acid eutectic, characterized in that: The molecular formula of the oxymatrine-caffeic acid co-crystal is C 15 H 25 N2O2·C9H7O4·3H2O, the crystal structure belongs to the monoclinic system, the space group is P21, and the unit cell parameters are α=90°,β=113.516(2)°,γ=90°,unit cell volume The minimum number of asymmetric units in the unit cell is Z = 2, and the crystal density is 1.333 g / cm 3 ; The powder X-ray diffraction pattern of the oxymatrine-caffeic acid co-crystal has characteristic diffraction peaks at 2θ of 9.64°, 12.02°, 12.92°, 14.7°, 15.48°, 18.32°, 18.94°, 20.76°, 22.3°, 23.5°, 23.88°, 25°, 26.28° and 28.64°; The infrared spectrum of the oxymatrine-caffeic acid co-crystal is at 3540 cm -1 , 3355cm -1 , 2942cm -1 , 2713cm -1 , 1918cm -1 , 1610cm -1 , 1521cm -1 , 1411cm -1 , 1382cm -1 , 1270cm -1 , 1220cm -1 , 1162cm -1 , 979cm -1 , 860cm -1 , 717cm -1 , 588cm -1 There is a characteristic absorption peak at the infrared spectrum, and the allowable deviation of the characteristic peak is ±2cm -1 ; The differential scanning calorimetry curve of the oxymatrine-caffeic acid co-crystal shows an endothermic peak in the range of 60-110°C and a melting point of 151°C; The thermogravimetric analysis curve of the oxymatrine-caffeic acid co-crystal shows that the co-crystal continuously loses crystal water at 25-108°C. After completely losing the crystal water, the structure remains stable in the range of 108-120°C. The oxymatrine-caffeic acid eutectic is a crystalline powder.

2. The method for preparing oxymatrine-caffeic acid co-crystal according to claim 1, wherein: The method comprises the following steps: weighing oxymatrine and caffeic acid respectively according to a molar ratio, placing the weighed oxymatrine and caffeic acid into a glass container and mixing them to obtain a mixed raw material powder, adding a solvent into the glass container, continuously stirring, heating the glass container in a water bath to dissolve the mixed raw materials to obtain a clear solution, cooling and filtering, standing and volatilizing, and obtaining light yellow block crystals, i.e., oxymatrine-caffeic acid co-crystals, after the solvent slowly evaporates.

3. The method for preparing oxymatrine-caffeic acid cocrystal according to claim 2, wherein: The molar ratio of oxymatrine to caffeic acid is 0.5-2:

1.

4. The method for preparing oxymatrine-caffeic acid cocrystal according to claim 2, wherein: The solvents used include a first solvent and a second solvent, the first solvent is distilled water, and the second solvent includes one or more of methanol, ethanol, isopropanol, acetonitrile and acetone.

5. The method for preparing oxymatrine-caffeic acid co-crystal according to claim 2, wherein: The volume ratio of the first solvent to the second solvent is 1:5-10.

6. The method for preparing oxymatrine-caffeic acid co-crystal according to claim 2, wherein: The solid-liquid ratio of the mixed raw material and the mixed solvent is 3-15 mg:1 mL.

7. The method for preparing oxymatrine-caffeic acid co-crystal according to claim 2, characterized in that: The water bath heating temperature is 10-60°C and the stirring time is 0.5-1h.

8. The method for preparing oxymatrine-caffeic acid co-crystal according to claim 2, wherein: The static volatilization temperature is 10-60℃ and the time is 1-30 days.

9. Use of the oxymatrine-caffeic acid co-crystal according to claim 1 in anti-inflammatory, antibacterial drugs or food additives.

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