Luteolin-4, 4 '-dipyridyl eutectic, eutectic solvate and preparation method of luteolin-4, 4'-dipyridyl eutectic

Abstract

The invention provides a luteolin-4, 4 '-dipyridyl eutectic, a eutectic solvate and a preparation method of the eutectic and the eutectic solvate, and belongs to the technical field of pharmaceutical co-crystals. According to the luteolin-4, 4 'dipyridyl eutectic and the eutectic solvate provided by the invention, O-H..N intermolecular hydrogen bonds between luteolin and 4, 4' dipyridyl are utilized for bonding, the molecular structure has excellent stability, the solubility of luteolin can be improved, and the problems of low solubility and low bioavailability of luteolin are solved. The result of the embodiment shows that the solubility of the luteolin-4, 4 'dipyridyl 1: 1 eutectic solvate provided by the invention is 2.51 times of that of luteolin, and the solubility of the luteolin-4, 4' dipyridyl 2: 1 eutectic solvate provided by the invention is 1.32 times of that of the luteolin.

Description

Technical Field

[0001] The present invention relates to the technical field of drug co-crystals, and in particular to a luteolin-4,4'-bipyridine co-crystal and a co-crystal solvate and a preparation method thereof. Background Art

[0002] Luteolin is a naturally occurring flavonoid compound that is commonly found in many plants. Several studies have shown that luteolin has pharmacological activities such as anti-cancer, anti-inflammatory and antioxidant activities, and can be used as a potential drug candidate for Alzheimer's disease. However, the low solubility of luteolin in water (only about 50.6 μg / mL) and low bioavailability limit its further application as a drug.

[0003] Pharmaceutical cocrystals are a new crystal form formed by the active pharmaceutical ingredient (API) and the cocrystal former (CCF) through weak intermolecular forces (such as hydrogen bonds, halogen bonds, van der Waals forces, etc.). Pharmaceutical cocrystals do not change the molecular structure of the active pharmaceutical ingredient, but can change the solubility, dissolution rate, bioavailability, hygroscopicity, compressibility, granulation and stability of the active pharmaceutical ingredient. They are the forefront and focus of current pharmaceutical crystal research. Therefore, the use of pharmaceutical cocrystals is particularly important for solving the problems of low solubility and low bioavailability of luteolin. Summary of the invention

[0004] The object of the present invention is to provide a luteolin-4,4'-bipyridine cocrystal and cocrystal solvate and a preparation method thereof. The luteolin-4,4'-bipyridine cocrystal and cocrystal solvate provided by the present invention can significantly improve the solubility of luteolin, thereby improving the bioavailability of luteolin.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a luteolin-4,4'-bipyridine cocrystal solvate, wherein the molar ratio of luteolin to 4,4'-bipyridine in the luteolin-4,4'-bipyridine cocrystal solvate is 1:1, and the solvent of the luteolin-4,4'-bipyridine cocrystal solvate is ethyl acetate.

[0007] Preferably, the luteolin-4,4'-bipyridine cocrystal solvate is a triclinic crystal system, a Pī space group, and the unit cell parameters are: α=97.518(3)°, β=98.986(3)°, γ=110.830(3)°.

[0008] Preferably, the luteolin-4,4'-bipyridine cocrystal solvate has an X-ray powder diffraction pattern expressed as 2θ±0.2°, and the 2θ angle values ​​of the X-ray powder diffraction pattern have diffraction peaks at 11.66°, 12.42°, 13.36°, 17.19°, 18.36°, 19.20°, 19.55°, 20.58°, 24.34°, 25.47°, 26.93° and 28.70°.

[0009] Preferably, the characteristic peak of the Raman spectrum of the luteolin-4,4'-bipyridine cocrystal solvate is 1607.4 cm -1 、1578.3cm -1 、1490.6cm -1 、1394.1cm -1 、1291.8cm -1 、1263.8cm -1 、1124.9cm -1 、1007.0cm -1 、787.5cm -1 、590.5cm -1 、490.4cm -1 and 272.4cm -1 .

[0010] The present invention also provides a method for preparing the luteolin-4,4'-bipyridine cocrystal solvate described in the above technical solution, comprising:

[0011] The luteolin, 4,4'-bipyridine and ethyl acetate are stirred at room temperature, and then filtered to obtain a filter cake, and the filter cake is dried to obtain a luteolin-4,4'-bipyridine cocrystal solvate;

[0012] Alternatively, luteolin, 4,4'-bipyridine and ethyl acetate are mixed, and then filtered to obtain a filtrate, and the filtrate is allowed to stand to obtain a luteolin-4,4'-bipyridine cocrystal solvate;

[0013] The molar ratio of the luteolin to 4,4'-bipyridine is 1.5:1 to 1:2.5.

[0014] The present invention also provides a luteolin-4,4'-bipyridine co-crystal, wherein the molar ratio of luteolin to 4,4'-bipyridine in the luteolin-4,4'-bipyridine co-crystal is 2:1.

[0015] Preferably, the luteolin-4,4'-bipyridine cocrystal has an X-ray powder diffraction pattern expressed as 2θ±0.2°, and the X-ray powder diffraction pattern comprises diffraction peaks at 2θ angle values ​​of 7.08°, 9.32°, 12.17°, 12.88°, 14.00°, 14.23°, 15.32°, 18.61°, 21.52 and 26.97°.

[0016] Preferably, the characteristic peak of the Raman spectrum of the luteolin-4,4'-bipyridine cocrystal is 1604.8 cm -1 、1566.0cm -1 、1434.3cm -1 、1314.6cm -1 、1262.0cm -1 、1228.6cm -1 、1135.4cm -1 、1008.8cm -1 、790.8cm -1 、638.0cm -1 、601.0cm -1 、510.0cm -1 、429.1cm -1 、190.0cm -1 、133.8cm -1 and 65.2cm -1 .

[0017] The present invention also provides a method for preparing the luteolin-4,4'-bipyridine cocrystal described in the above technical solution, comprising:

[0018] The luteolin, 4,4'-bipyridine and solvent are stirred at room temperature, and then filtered to obtain a filter cake, and the filter cake is dried to obtain a luteolin-4,4'-bipyridine cocrystal;

[0019] Alternatively, luteolin, 4,4'-bipyridine and a solvent are mixed, and then filtered to obtain a filtrate, and the filtrate is allowed to stand to obtain a luteolin-4,4'-bipyridine cocrystal;

[0020] The ratio of the luteolin to 4,4'-bipyridine is 2.5:1 to 1.5:1.

[0021] Preferably, the stirring time at room temperature is 3 to 7 days.

[0022] The present invention provides a luteolin-4,4' bipyridine cocrystal and a cocrystal solvate, wherein the molar ratio of luteolin to 4,4' bipyridine in the luteolin-4,4' bipyridine cocrystal is 2:1; the molar ratio of luteolin to 4,4' bipyridine in the luteolin-4,4' bipyridine cocrystal solvate is 1:1, and the solvent of the luteolin-4,4' bipyridine cocrystal solvate is ethyl acetate. The present invention utilizes the OH···N intermolecular hydrogen bonding between luteolin and 4,4' bipyridine, and this molecular structure has excellent stability, can improve the solubility of luteolin, and solves the problem of low solubility and bioavailability of luteolin. The results of the examples show that the solubility of the luteolin-4,4'-bipyridine 1:1 cocrystal solvate provided by the present invention is 2.51 times that of luteolin; the solubility of the luteolin-4,4'-bipyridine 2:1 cocrystal provided by the present invention is 1.32 times that of luteolin. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The asymmetric unit structure diagram of the single crystal of luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate prepared in Example 3 of the present invention;

[0024] Figure 2 The X-ray powder diffraction (PXRD) patterns of luteolin, 4,4'-bipyridine, the luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate prepared in Example 1, and the luteolin-4,4'-bipyridine 2:1 cocrystal prepared in Example 4;

[0025] Figure 3 The Raman spectra of luteolin, 4,4'-bipyridine, the 1:1 ethyl acetate solvate of luteolin-4,4'-bipyridine cocrystal prepared in Example 1, and the 2:1 luteolin-4,4'-bipyridine cocrystal prepared in Example 4;

[0026] Figure 4 The differential scanning calorimetry (DSC) curves of luteolin, 4,4'-bipyridine, the luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate prepared in Example 1, and the luteolin-4,4'-bipyridine 2:1 cocrystal prepared in Example 4 of the present invention;

[0027] Figure 5 Thermogravimetric analysis (TGA) curves of luteolin, 4,4'-bipyridine, 1:1 luteolin-4,4'-bipyridine ethyl acetate solvate prepared in Example 1, and 2:1 luteolin-4,4'-bipyridine eutectic prepared in Example 4;

[0028] Figure 6The dissolution curves of the luteolin of the present invention, the luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate prepared in Example 1, and the luteolin-4,4'-bipyridine 2:1 cocrystal prepared in Example 4 in 0.5% Tween 80 aqueous solution within 4 hours;

[0029] Figure 7 The dissolution curves of the luteolin of the present invention, the luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate prepared in Example 1, and the luteolin-4,4'-bipyridine 2:1 cocrystal prepared in Example 4 in 0.5% Tween 80 aqueous solution within 24 hours. DETAILED DESCRIPTION

[0030] The present invention provides a luteolin-4,4'-bipyridine cocrystal solvate, wherein the molar ratio of luteolin to 4,4'-bipyridine in the luteolin-4,4'-bipyridine cocrystal solvate is 1:1, and the solvent of the luteolin-4,4'-bipyridine cocrystal solvate is ethyl acetate.

[0031] In the present invention, the structural formula of luteolin is preferably as shown in formula (I):

[0032]

[0033] In the present invention, the structural formula of the 4,4'-bipyridine is preferably as shown in formula (II):

[0034]

[0035] In the present invention, the luteolin-4,4'-bipyridine cocrystal solvate is preferably a triclinic system, a Pī space group, and the unit cell parameters are: α=97.518(3)°, β=98.986(3)°, γ=110.830(3)°.

[0036] In the present invention, the luteolin-4,4'-bipyridine cocrystal solvate preferably has an X-ray powder diffraction pattern expressed as 2θ±0.2°, and the 2θ angle values ​​of the X-ray powder diffraction pattern have diffraction peaks at 11.66°, 12.42°, 13.36°, 17.19°, 18.36°, 19.20°, 19.55°, 20.58°, 24.34°, 25.47°, 26.93° and 28.70°. X-ray powder diffraction pattern of the luteolin-4,4'-bipyridine cocrystal solvate provided by the present invention Figure 2 The θ angle value was the above value, and it had characteristic peaks different from those of luteolin and 4,4'-bipyridine, proving that the new substance was a luteolin-4,4'-bipyridine cocrystal solvate.

[0037] In the present invention, the characteristic peak of the Raman spectrum of the luteolin-4,4'-bipyridine cocrystal solvate is preferably 1607.4 cm -1 、1578.3cm -1 、1490.6cm -1 、1394.1cm -1 、1291.8cm -1 、1263.8cm -1 、1124.9cm -1 、1007.0cm -1 、787.5cm -1 、590.5cm -1 、490.4cm -1 and 272.4cm -1 The characteristic peaks of the Raman spectrum of the luteolin-4,4'-bipyridine cocrystal solvate provided by the present invention are the above values, and have characteristic peaks different from those of luteolin and 4,4'-bipyridine, proving that the new substance is the luteolin-4,4'-bipyridine cocrystal solvate.

[0038] In the present invention, the melting point of the luteolin-4,4'-bipyridine cocrystal solvate is preferably 340.9° C. The melting point of the luteolin-4,4'-bipyridine cocrystal solvate provided by the present invention is the above value, indicating that the cocrystal solvate provided by the present invention has excellent thermal stability.

[0039] The present invention also provides a method for preparing the luteolin-4,4'-bipyridine cocrystal solvate described in the above technical solution, comprising: stirring luteolin, 4,4'-bipyridine and ethyl acetate at room temperature, then filtering to obtain a filter cake, and drying the filter cake to obtain the luteolin-4,4'-bipyridine cocrystal solvate;

[0040] Alternatively, luteolin, 4,4'-bipyridine and a solvent are mixed and then filtered to obtain a filtrate, and the filtrate is allowed to stand to obtain a luteolin-4,4'-bipyridine cocrystal solvate.

[0041] In one technical solution of the present invention, luteolin, 4,4'-bipyridine and ethyl acetate are stirred at room temperature, and then filtered to obtain a filter cake, and the filter cake is dried to obtain a luteolin-4,4'-bipyridine eutectic solvate.

[0042] In the present invention, luteolin, 4,4'-bipyridine and ethyl acetate are stirred at room temperature, and then filtered to obtain a filter cake.

[0043] In the present invention, the molar ratio of luteolin to 4,4'-bipyridine is 1.5:1-1:2.5, preferably 1:1. The present invention controls the molar ratio of luteolin to 4,4'-bipyridine within the above range, which is more conducive to obtaining a luteolin-4,4'-bipyridine cocrystal solvate with higher purity.

[0044] In the present invention, the ratio of the mass of luteolin to the volume of ethyl acetate is preferably 50-200 mg / mL, more preferably 100 mg / mL. The present invention controls the ratio of the mass of luteolin to the volume of ethyl acetate within the above range, which is more conducive to the full reaction of luteolin and 4,4'-bipyridine to form luteolin-4,4'-bipyridine eutectic solvate.

[0045] In the present invention, the stirring time is preferably 3 to 7 days, more preferably 7 days. The present invention promotes the reaction of luteolin and 4,4'-bipyridine to form luteolin-4,4'-bipyridine eutectic solvate by stirring, which is more conducive to the formation of luteolin-4,4'-bipyridine eutectic solvate in large quantities.

[0046] The present invention has no special limitation on the filtering method. A conventional filtering method can be used to separate the solid formed by stirring luteolin, 4,4'-bipyridine and ethyl acetate at room temperature.

[0047] After obtaining the filter cake, the present invention dries the filter cake to obtain luteolin-4,4' bipyridine eutectic solvate. In the present invention, the drying temperature is preferably 30 to 50°C, more preferably 40°C; the drying time is preferably 12 to 48 hours, more preferably 24 hours. The present invention can fully dry the filter cake by drying at the above temperature without destroying the structure of the luteolin-4,4' bipyridine eutectic solvate. The present invention can prepare luteolin-4,4' bipyridine eutectic solvate on a large scale through this technical solution.

[0048] In another technical solution of the present invention, luteolin, 4,4'-bipyridine and ethyl acetate are mixed, and then filtered to obtain a filtrate, and the filtrate is allowed to stand to obtain a luteolin-4,4'-bipyridine cocrystal solvate.

[0049] In the present invention, the molar ratio of luteolin to 4,4'-bipyridine is 1.5:1 to 1:2.5, preferably 1:1. The present invention controls the molar ratio of luteolin to 4,4'-bipyridine within the above range, which is more conducive to obtaining a luteolin-4,4'-bipyridine cocrystal solvate with higher purity.

[0050] In the present invention, the ratio of the mass of luteolin to the volume of ethyl acetate is preferably 0.3-3 mg / mL, more preferably 0.7-2 mg / mL. The present invention controls the ratio of the mass of luteolin to the volume of ethyl acetate within the above range, which is more conducive to the full reaction of luteolin and 4,4'-bipyridine to form luteolin-4,4'-bipyridine eutectic solvate.

[0051] The present invention has no particular limitation on the method for mixing luteolin, 4,4'-bipyridine and ethyl acetate. A conventional mixing method can be used to dissolve luteolin and 4,4'-bipyridine in ethyl acetate to obtain a mixed solution of luteolin and 4,4'-bipyridine. In the present invention, the method for mixing luteolin, 4,4'-bipyridine and solvent is preferably heating or ultrasound. In the present invention, the heating temperature is preferably 40 to 60°C.

[0052] The present invention has no particular limitation on the filtering method. A conventional filtering method can be used to remove solid impurities in the mixed solution of luteolin and 4,4'-bipyridine.

[0053] After obtaining the filtrate, the present invention allows the filtrate to stand to obtain luteolin-4,4'-bipyridine cocrystal solvate.

[0054] In the present invention, the standing is preferably performed at room temperature, and the standing time is preferably 1 to 8 days, more preferably 8 days. In the present invention, the solvent in the filtrate is volatilized by standing to generate luteolin-4,4'-bipyridine cocrystal solvate.

[0055] In the present invention, the crystals obtained after standing are preferably filtered to obtain luteolin-4,4'-bipyridine cocrystal solvate. The present invention has no particular limitation on the filtering method, and a conventional filtering method can be used to separate the crystals from the solvent in the filtrate.

[0056] The method provided by the present invention is simple to operate and can obtain high-purity luteolin-4,4'-bipyridine cocrystal solvate. The luteolin-4,4'-bipyridine cocrystal solvate obtained by this technical solution exists in the form of a single crystal.

[0057] The present invention also provides a luteolin-4,4'-bipyridine co-crystal, wherein the molar ratio of luteolin to 4,4'-bipyridine in the luteolin-4,4'-bipyridine co-crystal is 2:1.

[0058] In the present invention, the luteolin-4,4'-bipyridine cocrystal preferably has an X-ray powder diffraction pattern expressed as 2θ±0.2°, and the 2θ angle values ​​of the X-ray powder diffraction pattern have diffraction peaks at 7.08°, 9.32°, 12.17°, 12.88°, 14.00°, 14.23°, 15.32°, 18.61°, 21.52° and 26.97°. X-ray powder diffraction pattern of luteolin-4,4'-bipyridine cocrystal provided by the present invention Figure 2 The θ angle value is the above value, and it has characteristic peaks different from those of luteolin and 4,4'-bipyridine, which proves that the new substance is luteolin-4,4'-bipyridine cocrystal.

[0059] In the present invention, the characteristic peak of the Raman spectrum of the luteolin-4,4'-bipyridine cocrystal is preferably 1604.8 cm -1 、1566.0cm -1 、1434.3cm -1 、1314.6cm -1 、1262.0cm -1 、1228.6cm -1 、1135.4cm -1 、1008.8cm -1 、790.8cm -1 、638.0cm -1 、601.0cm -1 、510.0cm -1 、429.1cm -1 、190.0cm -1 、133.8cm -1 and 65.2cm -1 The characteristic peaks of the Raman spectrum of the luteolin-4,4'-bipyridine cocrystal provided by the present invention are the above values, and have characteristic peaks different from those of luteolin and 4,4'-bipyridine, proving that the new substance is the luteolin-4,4'-bipyridine cocrystal.

[0060] In the present invention, the melting point of the luteolin-4,4'-bipyridine cocrystal is preferably 340.9° C. The melting point of the luteolin-4,4'-bipyridine cocrystal provided by the present invention is the above value, indicating that the cocrystal provided by the present invention has excellent thermal stability.

[0061] The molar ratio of luteolin to 4,4'-bipyridine in the luteolin-4,4'-bipyridine cocrystal provided by the present invention is 2:1, which can improve the solubility of luteolin and solve the problems of low solubility and bioavailability of luteolin.

[0062] The present invention also provides a method for preparing the luteolin-4,4'-bipyridine cocrystal described in the above technical solution, comprising:

[0063] The luteolin, 4,4'-bipyridine and solvent are stirred at room temperature, and then filtered to obtain a filter cake, and the filter cake is dried to obtain a luteolin-4,4'-bipyridine cocrystal;

[0064] Alternatively, luteolin, 4,4'-bipyridine and a solvent are mixed and then filtered to obtain a filtrate, and the filtrate is allowed to stand to obtain a luteolin-4,4'-bipyridine cocrystal.

[0065] In one technical solution of the present invention, luteolin, 4,4'-bipyridine and a solvent are stirred at room temperature, and then filtered to obtain a filter cake, and the filter cake is dried to obtain a luteolin-4,4'-bipyridine cocrystal.

[0066] In the present invention, luteolin, 4,4'-bipyridine and a solvent are stirred at room temperature, and then filtered to obtain a filter cake.

[0067] In the present invention, the molar ratio of luteolin to 4,4'-bipyridine is 2.5:1 to 1.5:1, preferably 2:1. The present invention controls the molar ratio of luteolin to 4,4'-bipyridine within the above range, which is more conducive to obtaining luteolin-4,4'-bipyridine cocrystal with higher purity.

[0068] In the present invention, the solvent preferably includes one or more of methanol, ethanol, acetone, dichloromethane, ethyl acetate, chloroform, acetonitrile, dimethyl sulfoxide, isopropanol and toluene, and more preferably ethyl acetate or methanol. The present invention uses the above solvents as reaction solvents, which is more conducive to the formation of luteolin-4,4'-bipyridine cocrystals with higher purity.

[0069] In the present invention, the mass ratio of luteolin to the volume of the solvent is preferably 50-200 mg / mL, more preferably 100 mg / mL. The present invention controls the mass ratio of luteolin to the volume of the solvent within the above range, which is more conducive to the full reaction of luteolin and 4,4'-bipyridine to form luteolin-4,4'-bipyridine eutectic.

[0070] In the present invention, the stirring time is preferably 3 to 7 days, more preferably 7 days. The present invention promotes the reaction of luteolin and 4,4'-bipyridine to form luteolin-4,4'-bipyridine cocrystals by stirring, which is more conducive to the formation of luteolin-4,4'-bipyridine cocrystals in large quantities.

[0071] The present invention has no special limitation on the filtering method. A conventional filtering method can be used to separate the solid formed by stirring luteolin, 4,4'-bipyridine and a solvent at room temperature.

[0072] After obtaining the filter cake, the present invention dries the filter cake to obtain luteolin-4,4' bipyridine cocrystal. In the present invention, the drying temperature is preferably 30 to 50°C, more preferably 40°C; the drying time is preferably 12 to 48 hours, more preferably 24 hours. The present invention can fully dry the filter cake by drying at the above temperature without destroying the structure of the luteolin-4,4' bipyridine cocrystal. The present invention can prepare luteolin-4,4' bipyridine cocrystal on a large scale through this technical solution.

[0073] In another technical solution of the present invention, luteolin, 4,4'-bipyridine and a solvent are mixed, and then filtered to obtain a filtrate, and the filtrate is allowed to stand to obtain a luteolin-4,4'-bipyridine cocrystal.

[0074] In the present invention, the molar ratio of luteolin to 4,4'-bipyridine is 2.5:1 to 1.5:1, preferably 2:1. The present invention controls the molar ratio of luteolin to 4,4'-bipyridine within the above range, which is more conducive to obtaining luteolin-4,4'-bipyridine cocrystal with higher purity.

[0075] In the present invention, the solvent preferably includes one or more of methanol, ethanol, acetone, dichloromethane, ethyl acetate, chloroform, acetonitrile, dimethyl sulfoxide, isopropanol and toluene, and more preferably ethyl acetate or methanol. The present invention uses the above solvents as reaction solvents, which is more conducive to the formation of luteolin-4,4'-bipyridine cocrystals with higher purity.

[0076] In the present invention, the mass ratio of luteolin to the volume of the solvent is preferably 0.3-3 mg / mL, more preferably 0.7-2 mg / mL. The present invention controls the mass ratio of luteolin to the volume of the solvent within the above range, which is more conducive to the full reaction of luteolin and 4,4'-bipyridine to form luteolin-4,4'-bipyridine eutectic.

[0077] The present invention has no particular limitation on the method for mixing the luteolin, 4,4'-bipyridine and solvent. A conventional mixing method can be used to dissolve luteolin and 4,4'-bipyridine in the solvent to obtain a mixed solution of luteolin and 4,4'-bipyridine. In the present invention, the method for mixing the luteolin, 4,4'-bipyridine and solvent is preferably heating or ultrasound. In the present invention, the heating temperature is preferably 40 to 60°C.

[0078] The present invention has no particular limitation on the filtering method. A conventional filtering method can be used to remove solid impurities in the mixed solution of luteolin and 4,4'-bipyridine.

[0079] After obtaining the filtrate, the present invention allows the filtrate to stand to obtain luteolin-4,4'-bipyridine cocrystal.

[0080] In the present invention, the standing is preferably performed at room temperature, and the standing time is preferably 1 to 8 days, more preferably 8 days. In the present invention, the solvent in the filtrate is volatilized by standing to generate luteolin-4,4'-bipyridine cocrystal.

[0081] In the present invention, the crystals obtained after standing are preferably filtered to obtain luteolin-4,4'-bipyridine cocrystals. The present invention has no special limitation on the filtering method, and a conventional filtering method can be used to separate the crystals from the solvent in the filtrate.

[0082] The method provided by the invention is simple to operate and can obtain high-purity luteolin-4,4'-bipyridine cocrystal.

[0083] The present invention utilizes the OH···N intermolecular hydrogen bonding between luteolin and 4,4'-bipyridine. This molecular structure has excellent stability, can improve the solubility of luteolin, and solves the problems of low solubility and bioavailability of luteolin.

[0084] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a 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 creative work are within the scope of protection of the present invention.

[0085] Example 1

[0086] A luteolin-4,4'-bipyridine cocrystal solvate, wherein the molar ratio of luteolin to 4,4'-bipyridine in the luteolin-4,4'-bipyridine cocrystal solvate is 1:1, and the solvent of the luteolin-4,4'-bipyridine cocrystal solvate is ethyl acetate.

[0087] The preparation method of the above-mentioned luteolin-4,4'-bipyridine cocrystal solvate is:

[0088] Weigh 200.1 mg of luteolin and 109.1 mg of 4,4'-bipyridine (the molar ratio of luteolin to 4,4'-bipyridine is 1:1) into 2 mL of ethyl acetate solvent, stir at room temperature for 7 days, and filter. The filter cake is dried at 40°C for 24 hours to obtain 241.0 mg of luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate, with a yield of 78.0%.

[0089] Example 2

[0090] A luteolin-4,4'-bipyridine cocrystal solvate, wherein the molar ratio of luteolin to 4,4'-bipyridine in the luteolin-4,4'-bipyridine cocrystal solvate is 1:1, and the solvent of the luteolin-4,4'-bipyridine cocrystal solvate is ethyl acetate.

[0091] The preparation method of the above-mentioned luteolin-4,4'-bipyridine cocrystal solvate is:

[0092] Weigh 300.2 mg of luteolin and 163.7 mg of 4,4'-bipyridine (the molar ratio of luteolin to 4,4'-bipyridine is 1:1) into 3 mL of ethyl acetate solvent, stir at room temperature for 7 days, and filter. The filter cake is dried at 40°C for 24 hours to obtain 388.9 mg of luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate, with a yield of 83.8%.

[0093] Example 3

[0094] A luteolin-4,4'-bipyridine cocrystal solvate, wherein the molar ratio of luteolin to 4,4'-bipyridine in the luteolin-4,4'-bipyridine cocrystal solvate is 1:1, and the solvent of the luteolin-4,4'-bipyridine cocrystal solvate is ethyl acetate.

[0095] The preparation method of the above-mentioned luteolin-4,4'-bipyridine cocrystal solvate is:

[0096] Weigh 10 mg of luteolin and 5.5 mg of 4,4'-bipyridine (the molar ratio of luteolin and 4,4'-bipyridine is 1:1) and add them to 15 mL of ethyl acetate solvent, heat to dissolve, and filter. The filtrate is slowly evaporated at room temperature, and block crystals grow after eight days. Filter by suction to obtain a single crystal of luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate.

[0097] The asymmetric unit structure of the single crystal of luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate prepared in this example is shown in Figure 1 As shown. Figure 1 In the figure, gray is C atoms, white balls are H atoms, red are O atoms, and blue are N atoms.

[0098] The luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate prepared in this example is a triclinic crystal system, Pī space group, and the unit cell parameters are: α=97.518(3)°, β=98.986(3)°, γ=110.830(3)°.

[0099] Example 4

[0100] A luteolin-4,4'-bipyridine co-crystal, wherein the molar ratio of luteolin to 4,4'-bipyridine in the luteolin-4,4'-bipyridine co-crystal is 2:1.

[0101] The preparation method of the above luteolin-4,4'-bipyridine cocrystal is:

[0102] Weigh 200.3 mg of luteolin and 54.6 mg of 4,4'-bipyridine (the molar ratio of luteolin to 4,4'-bipyridine is 2:1) into 2 mL of methanol solvent, stir at room temperature for 7 days, and filter. The filter cake is dried at 40°C for 24 hours to obtain 221.3 mg of luteolin-4,4'-bipyridine 2:1 cocrystal, with a yield of 86.8%.

[0103] Example 5

[0104] A luteolin-4,4'-bipyridine co-crystal, wherein the molar ratio of luteolin to 4,4'-bipyridine in the luteolin-4,4'-bipyridine co-crystal is 2:1.

[0105] The preparation method of the above luteolin-4,4'-bipyridine cocrystal is:

[0106] Weigh 300.1 mg of luteolin and 81.6 mg of 4,4'-bipyridine (the molar ratio of luteolin to 4,4'-bipyridine is 2:1) into 3 mL of methanol solvent, stir at room temperature for 7 days, and filter. The filter cake is dried at 40°C for 24 hours to obtain 336.7 mg of luteolin-4,4'-bipyridine 2:1 cocrystal, with a yield of 88.2%.

[0107] Test Example 1

[0108] The X-ray powder diffraction (PXRD) patterns of luteolin, 4,4'-bipyridine, the 1:1 ethyl acetate solvate of luteolin-4,4'-bipyridine cocrystal prepared in Example 1, and the 2:1 ethyl acetate solvate of luteolin-4,4'-bipyridine cocrystal prepared in Example 4 are shown in FIG. Figure 2 As shown. Figure 2 Wherein LUT is luteolin, 44B is 4,4'bipyridine, LUT-44B 1:1 is the luteolin-4,4'bipyridine 1:1 cocrystal ethyl acetate solvate prepared in Example 1, and LUT-44B 2:1 is the luteolin-4,4'bipyridine 2:1 cocrystal prepared in Example 4. Figure 2It can be concluded that the luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate has an X-ray powder diffraction pattern expressed as 2θ±0.2°, and the 2θ angle values ​​of the X-ray powder diffraction pattern are 11.66°, 12.42°, 13.36°, 17.19°, 18.36°, 19.20°, 19.55°, 20.58°, 24.34°, 25.47°, 26.9 The luteolin-4,4'-bipyridine 2:1 cocrystal has an X-ray powder diffraction pattern expressed as 2θ±0.2°, and the 2θ angle values ​​of the X-ray powder diffraction pattern have diffraction peaks at 7.08°, 9.32°, 12.17°, 12.88°, 14.00°, 14.23°, 15.32°, 18.61°, 21.52° and 26.97°. It can be seen that the luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate and luteolin-4,4'-bipyridine 2:1 cocrystal provided by the present invention have characteristic peaks different from those of luteolin and 4,4'-bipyridine, proving that new substances luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate and luteolin-4,4'-bipyridine 2:1 cocrystal are formed.

[0109] Test Example 2

[0110] The Raman spectra of luteolin, 4,4'-bipyridine, the 1:1 ethyl acetate solvate of luteolin-4,4'-bipyridine cocrystal prepared in Example 1, and the 2:1 ethyl acetate solvate of luteolin-4,4'-bipyridine cocrystal prepared in Example 4 are shown in FIG. Figure 3 As shown. Figure 3 It can be concluded that the characteristic peak of the Raman spectrum of luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate is 1607.4 cm -1 、1578.3cm -1 、1490.6cm -1 、1394.1cm -1 、1291.8cm -1 、1263.8cm -1 、1124.9cm -1 、1007.0cm -1 、787.5cm -1 、590.5cm -1 、490.4cm -1 and 272.4cm -1 The characteristic peak of the Raman spectrum of luteolin-4,4'-bipyridine 2:1 cocrystal is 1604.8cm -1 、1566.0cm -1 、1434.3cm -1 、1314.6cm -1、1262.0cm -1 、1228.6cm -1 、1135.4cm -1 、1008.8cm -1 、790.8cm -1 、638.0cm -1 、601.0cm -1 、510.0cm -1 、429.1cm -1 、190.0cm -1 、133.8cm -1 and 65.2cm -1 It can be seen that the luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate and luteolin-4,4'-bipyridine 2:1 cocrystal provided by the present invention have characteristic peaks different from those of luteolin and 4,4'-bipyridine, proving that new substances luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate and luteolin-4,4'-bipyridine 2:1 cocrystal are formed.

[0111] Test Example 3

[0112] The differential scanning calorimetry (DSC) curves of luteolin, 4,4'-bipyridine, the 1:1 ethyl acetate solvate of luteolin-4,4'-bipyridine cocrystal prepared in Example 1, and the 2:1 ethyl acetate solvate of luteolin-4,4'-bipyridine cocrystal prepared in Example 4 are shown in FIG. Figure 4 As shown. Figure 4 It can be concluded that the DSC spectrum of luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate shows an endothermic peak of 261.1°C and an endothermic peak of 289.4°C. These two peaks indicate that the cocrystal may have undergone a transformation during the heating process. The endothermic peak of 340.9°C is the melting peak, and the product melts, indicating that the melting point of luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate is 340.9°C; the DSC spectrum of luteolin-4,4'-bipyridine 2:1 cocrystal shows an endothermic peak of 267.3°C. This peak indicates that the cocrystal may have undergone a transformation during the heating process. The endothermic peak of 340.9°C is the melting peak, and the product melts, indicating that the melting point of luteolin-4,4'-bipyridine 2:1 cocrystal is 340.9°C.

[0113] Test Example 4

[0114] Thermogravimetric analysis (TGA) curves of luteolin, 4,4'-bipyridine, luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate prepared in Example 1, and luteolin-4,4'-bipyridine 2:1 cocrystal prepared in Example 4 are shown in FIG. Figure 5 As shown. Figure 5It can be concluded that the TGA (thermogravimetric analysis) characteristics of the 1:1 cocrystal ethyl acetate solvate of luteolin-4,4'-bipyridine are as follows: the first weight loss step at 110-170°C, with a weight loss of 8.11%, corresponding to the loss of ethyl acetate solvent and the first weight loss step of LUT; the second weight loss step at 170-243°C, with a weight loss of 38.33%, corresponding to the weight loss of 44B. According to the weight loss ratio of 44B and the molecular weight of each substance, it can be calculated that the stoichiometric ratio of LUT and 44B in the cocrystal is approximately 1:1; 315-39 The third weight loss step at 1℃, with a weight loss of 32.49%, corresponds to the second weight loss step of LUT; the TGA characteristics of luteolin-4,4'-bipyridine 2:1 cocrystal are as follows: the first weight loss step at 223-263℃, with a weight loss of 21.13%, corresponding to the weight loss of 44B. According to the weight loss ratio of 44B and the molecular weight of each substance, it can be calculated that the stoichiometric ratio of LUT and 44B in the cocrystal is approximately 2:1; the second weight loss step at 327-409℃, with a weight loss of 32.06%, corresponds to the second weight loss step of LUT.

[0115] Test Example 5

[0116] (1) Dissolution test of luteolin, luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate prepared in Example 1, and luteolin-4,4'-bipyridine 2:1 cocrystal prepared in Example 4 in 0.5% Tween 80 aqueous solution:

[0117] The above samples (equivalent to 40 mg of luteolin) were respectively passed through an 80-mesh sieve and added into a conical flask containing 40 mL of 0.5% Tween 80 aqueous solution. The conical flask was placed at 37°C and stirred at 200 rpm for 24 hours. Samples were taken at 2 min, 5 min, 15 min, 30 min, 60 min, 120 min, 240 min, 480 min and 1440 min, respectively, and after passing through a 0.45 μm filter and diluting by half, the sample concentration was detected by HPLC (high performance liquid chromatography) (n=3).

[0118] The test conditions are as follows:

[0119] Instrument: Shimadzu LC-2010A

[0120] Chromatographic column: Shimadzu Superb IIC18, 5μm, 4,6mm×250mm

[0121] Mobile phase: A: methanol, B: water, methanol concentration: 60%

[0122] Column temperature: 35°C

[0123] Flow rate: 1mL

[0124] Injection volume: 20 μL.

[0125] The dissolution curves of luteolin, luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate prepared in Example 1, and luteolin-4,4'-bipyridine 2:1 cocrystal prepared in Example 4 in 0.5% Tween 80 aqueous solution within 4 h are as follows: Figure 6 The dissolution curves of luteolin, luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate prepared in Example 1 and luteolin-4,4'-bipyridine 2:1 cocrystal prepared in Example 4 in 0.5% Tween 80 aqueous solution within 24 hours are shown as Figure 7 shown.

[0126] from Figure 6 and Figure 7 It can be seen that compared with luteolin, the luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate and luteolin-4,4'-bipyridine 2:1 cocrystal synthesized in the present invention both effectively improved the solubility of luteolin. Within 24 hours, the solubility of luteolin in the two cocrystals in 0.5% Tween 80 aqueous solution was higher than the solubility of pure luteolin. The maximum solubility of luteolin was 43.1 μg / mL, while the maximum solubility of luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate was 108.21 μg / mL, and the solubility of luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate was 2.51 times that of luteolin; the maximum solubility of luteolin-4,4'-bipyridine 2:1 cocrystal was 56.8 μg / mL, and the solubility of luteolin-4,4'-bipyridine 2:1 cocrystal ethyl acetate solvate was 1.32 times that of luteolin. The two products have good stability in 0.5% Tween 80 aqueous solution. According to the Raman characterization of the residual solid after the solubility experiment and the solubility change of the cocrystal within 24 hours, the luteolin-4,4'-bipyridine 1:1 cocrystal ethyl acetate solvate did not decompose within 4 hours (the solubility did not decrease), partially decomposed within 24 hours, the solubility decreased significantly, and the Raman characterization showed that part of the spectrum was consistent with the spectrum of luteolin. The luteolin-4,4'-bipyridine 2:1 cocrystal did not decompose within 24 hours, the solubility did not decrease, and the Raman characterization showed that the spectrum did not change.

[0127] It can be seen from the above results that the luteolin-4,4'-bipyridine cocrystal and cocrystal solvate provided by the present invention can significantly improve the solubility of luteolin, solving the problem of low bioavailability caused by the low solubility of luteolin.

[0128] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A luteolin-4,4'-bipyridine cocrystal solvate, wherein the molar ratio of luteolin to 4,4'-bipyridine in the luteolin-4,4'-bipyridine cocrystal solvate is 1:1, and the solvent of the luteolin-4,4'-bipyridine cocrystal solvate is ethyl acetate.

2. The luteolin-4,4'-bipyridine cocrystal solvate according to claim 1, characterized in that: The luteolin-4,4'-bipyridine cocrystal solvate is a triclinic crystal system, Pī space group, and the unit cell parameters are: α=97.518(3)°, β=98.986(3)°, γ=110.830(3)°.

3. The luteolin-4,4'-bipyridine cocrystal solvate according to claim 1, characterized in that: The luteolin-4,4'-bipyridine cocrystal solvate has an X-ray powder diffraction pattern expressed as 2θ±0.2°, and the 2θ angle values ​​of the X-ray powder diffraction pattern have diffraction peaks at 11.66°, 12.42°, 13.36°, 17.19°, 18.36°, 19.20°, 19.55°, 20.58°, 24.34°, 25.47°, 26.93° and 28.70°.

4. The luteolin-4,4'-bipyridine cocrystal solvate according to claim 1, characterized in that: The characteristic peak of the Raman spectrum of the luteolin-4,4'-bipyridine cocrystal solvate is 1607.4 cm -1 、1578.3cm -1 、1490.6cm -1 、1394.1cm -1 、1291.8cm -1 、1263.8cm -1 、1124.9cm -1 、1007.0cm -1 、787.5cm -1 、590.5cm -1 、490.4cm -1 and 272.4cm -1 .

5. The method for preparing the luteolin-4,4'-bipyridine cocrystal solvate according to any one of claims 1 to 4, comprising: The luteolin, 4,4'-bipyridine and ethyl acetate are stirred at room temperature, and then filtered to obtain a filter cake, and the filter cake is dried to obtain a luteolin-4,4'-bipyridine cocrystal solvate; Alternatively, luteolin, 4,4'-bipyridine and ethyl acetate are mixed, and then filtered to obtain a filtrate, and the filtrate is allowed to stand to obtain a luteolin-4,4'-bipyridine cocrystal solvate; The molar ratio of the luteolin to 4,4'-bipyridine is 1.5:1 to 1:2.

5.

6. A luteolin-4,4'-bipyridine co-crystal, wherein the molar ratio of luteolin to 4,4'-bipyridine in the luteolin-4,4'-bipyridine co-crystal is 2:

1.

7. The luteolin-4,4'-bipyridine cocrystal according to claim 6, characterized in that: The luteolin-4,4'-bipyridine cocrystal has an X-ray powder diffraction pattern expressed as 2θ±0.2°, and the 2θ angle values ​​of the X-ray powder diffraction pattern have diffraction peaks at 7.08°, 9.32°, 12.17°, 12.88°, 14.00°, 14.23°, 15.32°, 18.61°, 21.52° and 26.97°.

8. The luteolin-4,4'-bipyridine cocrystal according to claim 6, characterized in that: The characteristic peak of the Raman spectrum of the luteolin-4,4'-bipyridine cocrystal is 1604.8 cm -1 、1566.0cm -1 、1434.3cm -1 、1314.6cm -1 、1262.0cm -1 、1228.6cm -1 、1135.4cm -1 、1008.8cm -1 、790.8cm -1 、638.0cm -1 、601.0cm -1 、510.0cm -1 、429.1cm -1 、190.0cm -1 、133.8cm -1 and 65.2cm -1 .

9. The method for preparing the luteolin-4,4'-bipyridine cocrystal according to any one of claims 6 to 8, comprising: The luteolin, 4,4'-bipyridine and solvent are stirred at room temperature, and then filtered to obtain a filter cake, and the filter cake is dried to obtain a luteolin-4,4'-bipyridine cocrystal; Alternatively, luteolin, 4,4'-bipyridine and a solvent are mixed, and then filtered to obtain a filtrate, and the filtrate is allowed to stand to obtain a luteolin-4,4'-bipyridine cocrystal; The ratio of the luteolin to 4,4'-bipyridine is 2.5:1 to 1.5:

1.

10. The preparation method according to claim 9, characterized in that: The stirring time at room temperature is 3 to 7 days.

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