Eutectic of L-carnitine and plant essential oil active ingredients as well as preparation method and application of eutectic

Abstract

The invention relates to the technical field of compound eutectic crystals, and discloses an L-carnitine and plant essential oil active component eutectic crystal and a preparation method and application thereof. The eutectic crystal is prepared from the following raw materials: L-carnitine and plant essential oil active ingredients, the molar ratio of the L-carnitine to the active ingredients of the plant essential oil is 1: 1; the plant essential oil active component is selected from at least one of thymol and carvacrol. The eutectic crystal provided by the invention is formed by at least one of thymol and carvacrol and L-carnitine, is low in hygroscopicity and volatility and good in stability, and overcomes the defects that single L-carnitine is strong in hygroscopicity and inconvenient to process and store, and single thymol or carvacrol is strong in volatility and poor in stability; compared with single thymol or carvacrol, the eutectic crystal shows lower minimum inhibitory concentration on escherichia coli, candida albicans, salmonella enteritidis, aspergillus niger and the like, and has a good antibacterial effect.

Description

Technical Field

[0001] The present invention relates to the technical field of compound co-crystals, and in particular to a co-crystal of L-carnitine and an active ingredient of plant essential oil, and a preparation method and application thereof. Background Art

[0002] The active ingredients of plant essential oils such as thymol and carvacrol are a class of natural antimicrobial agents, showing broad-spectrum antimicrobial activity and good biodegradability, and are not prone to drug resistance. In addition, thymol and carvacrol also have antioxidant and antiseptic effects, have unique aroma and flavor, and have broad application prospects in industries such as food, health products, daily chemicals, feed, veterinary drugs, medicine, and pesticides. However, these active ingredients of plant essential oils have low melting points and strong volatility, are easily affected by the external environment (light, heat, humidity, and air), are difficult to preserve, and cause a large loss of effective ingredients, which is severely limited in practical applications.

[0003] L-carnitine is a naturally occurring amino acid substance in the human body that can convert fat into energy. It has many physiological functions such as weight loss, anti-fatigue, and anti-aging. Its main application areas include food additives, feed additives, and drug treatment. As a food additive, L-carnitine is widely used in infant food, weight loss food, athlete food, nutritional supplements for the elderly, and nutritional enhancers for vegetarians. As a feed additive, it can promote the normal energy metabolism of animals, save protein, improve feed utilization, promote the growth of livestock and poultry, enhance animal immunity and disease resistance, and improve meat quality. As a drug treatment, L-carnitine can be used in the clinical treatment of cardiovascular diseases, kidney-related diseases, diabetes and its complications, liver-related diseases, septic shock, and other diseases. However, L-carnitine is very easy to absorb moisture, which brings great inconvenience to its processing, storage, and application. Summary of the invention

[0004] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, one of the objects of the present invention is to provide a co-crystal; the second object of the present invention is to provide a method for preparing the co-crystal; the third object of the present invention is to provide a product containing the co-crystal.

[0005] The basic principle of the present invention is described as follows:

[0006] Cocrystals refer to multi-component crystals with a specific stoichiometric ratio formed by the interaction of an active ingredient with other solid small molecules, or two active ingredients, through non-covalent bonds such as hydrogen bonds. Cocrystal technology can improve the physical and chemical properties and enhance the efficacy by changing the intermolecular interactions and crystal stacking mode while retaining the original molecular structure and biological activity of the active ingredient.

[0007] The present invention forms a stable co-crystal with L-carnitine and thymol, carvacrol and other plant essential oil active ingredients through the co-crystal technology, which can not only ensure the original efficacy of the plant essential oil active ingredients, reduce volatility, and enhance stability, but also significantly reduce the hygroscopicity of L-carnitine, so that both can better exert their respective efficacy and broaden their application fields.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] The first aspect of the present invention provides a cocrystal, comprising the following raw materials: L-carnitine and active ingredients of plant essential oils; the molar ratio of L-carnitine to the active ingredients of plant essential oils is 1:1; and the active ingredients of plant essential oils are at least one of thymol and carvacrol.

[0010] Preferably, the co-crystal of L-carnitine and active ingredient of plant essential oil has diffraction peaks at 2θ values ​​of 4.4±0.2°, 18.3±0.2°, 18.8±0.2°, 19.9±0.2°, and 21.9±0.2° in the X-ray powder diffraction spectrum.

[0011] Preferably, when the active ingredient of the plant essential oil is thymol, the co-crystal is a co-crystal of L-carnitine and thymol; the co-crystal of L-carnitine and thymol also has at least one diffraction peak at 2θ values ​​of 13.7±0.2°, 14.5±0.2°, 15.5±0.2°, 24.7±0.2°, 25.7±0.2°, and 27.0±0.2° in the X-ray powder diffraction spectrum.

[0012] In some specific embodiments of the present invention, in the composition formed by L-carnitine and thymol, the molar ratio of L-carnitine to thymol can be (1-9):1, wherein a part of the components exists in the form of the L-carnitine and thymol co-crystal, and the other part of the components exists in the form of free L-carnitine; that is, in addition to the L-carnitine and thymol co-crystal described in the present invention, the composition of L-carnitine and thymol can also contain excess L-carnitine and other auxiliary materials.

[0013] Preferably, when the active ingredient of the plant essential oil is carvacrol, the co-crystal is a co-crystal of L-carnitine and carvacrol; the co-crystal of L-carnitine and carvacrol also has at least one diffraction peak at 2θ values ​​of 5.7±0.2°, 13.2±0.2°, 14.1±0.2°, 15.0±0.2°, 17.6±0.2°, 19.2±0.2°, 20.4±0.2°, 23.3±0.2°, and 28.5±0.2° in the X-ray powder diffraction spectrum.

[0014] In some specific embodiments of the present invention, in the composition formed by L-carnitine and carvacrol, the molar ratio of L-carnitine to carvacrol can be (1-9):1, wherein a part of the components exist in the form of the L-carnitine and carvacrol co-crystal, and the other part of the components exist in the form of free L-carnitine; that is, in addition to the L-carnitine and carvacrol co-crystal described in the present invention, the composition of L-carnitine and carvacrol may also contain excess L-carnitine and other auxiliary materials.

[0015] Preferably, when the active ingredients of the plant essential oil are thymol and carvacrol, the co-crystal is a co-crystal of L-carnitine, thymol and carvacrol; the molar ratio of thymol to carvacrol is 1:(0.5-2); the co-crystal of L-carnitine, thymol and carvacrol also has at least one diffraction peak at 2θ values ​​of 5.7±0.2°, 13.7±0.2°, 14.5±0.2°, 17.6±0.2°, 23.3±0.2°, 24.7±0.2°, and 25.7±0.2° in the X-ray powder diffraction spectrum.

[0016] The second aspect of the present invention provides a method for preparing the co-crystal according to the first aspect of the present invention, wherein the preparation method comprises any one of the following two methods:

[0017] Method 1: mixing the L-carnitine with the active ingredient of plant essential oil under solvent conditions, and collecting the solid by solid-liquid separation to obtain the co-crystal;

[0018] Method 2: Applying mechanical force to make the L-carnitine contact and react with the active ingredient of plant essential oil to obtain the co-crystal.

[0019] Preferably, in method 1, the solvent is selected from at least one of water, alcohol solvents, ester solvents, ketone solvents, alkane solvents, aromatic hydrocarbon solvents and halogenated alkane solvents; further preferably, the solvent is selected from at least one of water, methanol, ethanol, isopropanol, ethyl acetate, isopropyl acetate, acetone, methyl tert-butyl ether, n-hexane and n-heptane.

[0020] Preferably, in the method 1, the ratio of the total mass of the L-carnitine and the active ingredients of the plant essential oil to the volume of the solvent is 1g:(5-50)mL; further preferably, the ratio of the total mass of the L-carnitine and the active ingredients of the plant essential oil to the volume of the solvent is 1g:(5-10)mL.

[0021] Preferably, the method 1 is specifically as follows: mixing the L-carnitine, the active ingredient of the plant essential oil and a solvent, stirring to obtain a suspension, filtering under reduced pressure, and drying the filter cake to obtain the co-crystal.

[0022] Preferably, the process parameters of the method 1 include: a stirring rate of 200-800 rpm, preferably 600 rpm, a stirring time of 2-24 h, preferably 6 h;

[0023] Preferably, in the method 2, the device for applying mechanical force is preferably a ball mill, a pulverizer, a mixer, an extruder or a stirring device.

[0024] Preferably, the process parameters of method 2 satisfy at least one of the following:

[0025] 1) Grinding frequency 5-60 Hz, preferably 20 Hz; grinding time 5-60 min, preferably 30 min;

[0026] 2) Crushing time 1-60min, preferably 2min.

[0027] Preferably, method 2 includes adding a co-solvent; the co-solvent is selected from at least one of alcohol solvents, ester solvents, ketone solvents, alkane solvents, aromatic hydrocarbon solvents and halogenated alkane solvents; further preferably, the co-solvent is selected from at least one of methanol, ethanol, isopropanol, ethyl acetate, isopropyl acetate, acetone, methyl tert-butyl ether, n-hexane and n-heptane.

[0028] Preferably, the method 2 is specifically as follows: adding the L-carnitine and the active ingredient of the plant essential oil into a ball mill, a pulverizer, a mixer, an extruder or a stirring device, and using mechanical force to make the L-carnitine and the active ingredient of the plant essential oil fully contact and react to obtain the co-crystal.

[0029] The third aspect of the present invention provides a product, comprising the co-crystal described in the first aspect of the present invention.

[0030] Preferably, the product includes food, health care products, feed, daily chemical products or medicines.

[0031] Preferably, the food may further include a main food ingredient and food additives acceptable to food, wherein the food additives include but are not limited to sweeteners, flavoring agents, preservatives, fragrances and coloring agents.

[0032] Preferably, the food includes food and beverage, and the co-crystal is added to the food and beverage in an amount of 0.1-4 mg / mL.

[0033] Preferably, the feed may further include a feed base, and feed adjuvants, wherein the feed base includes but is not limited to soybean meal and hay, and the feed adjuvants include but are not limited to sweeteners, flavoring agents, preservatives, aroma agents and coloring agents.

[0034] Preferably, the co-crystal is added in an amount of 50-200 mg / kg in feed.

[0035] Preferably, the daily chemical products may include daily chemical product main ingredients and daily chemical product additives, and the daily chemical product additives include but are not limited to solvents, flavoring agents, preservatives, flavors and colorants.

[0036] Preferably, the medicines include veterinary medicines and human medicines.

[0037] Preferably, the medicine may further include a pharmaceutically active ingredient and pharmaceutically acceptable excipients, including but not limited to carriers, diluents, adjuvants and colorants.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1) The co-crystal provided by the present invention is formed by at least one of thymol and carvacrol and L-carnitine. The co-crystal has low hygroscopicity and volatility, good stability, and the effective ingredient is not easily lost, which overcomes the defects of single L-carnitine, such as strong hygroscopicity, inconvenience in processing and storage, and overcomes the defects of single thymol or carvacrol, such as strong volatility and poor stability. Compared with single thymol or carvacrol, the co-crystal exhibits a lower minimum inhibitory concentration against Escherichia coli, Candida albicans, Salmonella enteritidis, Aspergillus niger, etc., and has a better antibacterial effect;

[0040] 2) The method for preparing the cocrystal provided by the present invention has simple steps, good reproducibility, and is suitable for industrial production;

[0041] 3) The co-crystal provided by the present invention exhibits excellent antibacterial effects against Escherichia coli, Staphylococcus aureus, Candida albicans, Salmonella enteritidis, Aspergillus niger, etc., and can be applied to food, health products, feed, daily chemical products and medicines. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is the X-ray powder diffraction spectrum of the L-carnitine and thymol cocrystal prepared in Example 1 of the present invention;

[0043] Figure 2 is a differential scanning calorimetry analysis diagram of L-carnitine and thymol cocrystal prepared in Example 1 of the present invention;

[0044] Figure 3 is a Fourier transform infrared spectrum of the L-carnitine and thymol cocrystal prepared in Example 1 of the present invention;

[0045] Figure 4 is the X-ray powder diffraction spectrum of the L-carnitine and carvacrol cocrystal prepared in Example 11 of the present invention;

[0046] Figure 5 is a differential scanning calorimetry analysis diagram of the L-carnitine and carvacrol cocrystal prepared in Example 11 of the present invention;

[0047] Figure 6 is a Fourier transform infrared spectrum of the L-carnitine and carvacrol cocrystal prepared in Example 11 of the present invention;

[0048] Figure 7 is the X-ray powder diffraction spectrum of the co-crystal of L-carnitine, thymol and carvacrol prepared in Example 22 of the present invention;

[0049] Figure 8 It is a comparison chart of the volatilization curves of free thymol, L-carnitine and thymol cocrystal, free carvacrol, L-carnitine and carvacrol cocrystal;

[0050] Fig. 9 This is a comparison of the inhibitory effects of free thymol, L-carnitine and thymol co-crystal on Escherichia coli in tomato juice. DETAILED DESCRIPTION

[0051] The present invention is further described in detail below by specific examples. The raw materials, reagents or devices used in the examples can be obtained from conventional commercial sources or by prior art methods unless otherwise specified. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0052] The detection instruments and methods involved in the following embodiments include:

[0053] 1. X-ray powder diffraction analysis: using Rigaku MiniFlex 600 diffractometer from Rigaku Co., Ltd., Cu-Kα ray The voltage was 40 kV, the current was 150 mA, the step size was 0.01°, the scanning speed was 20° / min, the scanning range was 3.0-40.0°, and the test temperature was room temperature;

[0054] 2. Differential Scanning Calorimetry (DSC): The samples were tested using a DSC 214 differential calorimeter from NETZSCH Scientific Instruments Co., Ltd. The atmosphere was nitrogen and the heating rate was 10°C / min.

[0055] 3. Infrared spectrum analysis: Bruker Vertex7 Fourier transform infrared spectrometer was used for detection, with a detection range of 4000-500cm -1 , resolution 0.2cm -1 , data were collected at room temperature.

[0056] Example 1

[0057] In this embodiment, a L-carnitine and thymol co-crystal is prepared, and the steps are as follows:

[0058] 2 mmol of L-carnitine and 2 mmol of thymol were weighed, added into a ball mill together with a steel ball with a diameter of 1 cm, and ground at a frequency of 20 Hz for 30 minutes to obtain a white powder of L-carnitine and thymol cocrystal.

[0059] The L-carnitine and thymol cocrystal prepared in Example 1 was subjected to X-ray powder diffraction analysis. Figure 1 is the X-ray powder diffraction pattern of the L-carnitine and thymol co-crystal in Example 1. The X-ray powder diffraction analysis data are shown in Table 1:

[0060] Table 1 X-ray powder diffraction analysis data of L-carnitine and thymol cocrystal in Example 1

[0061]

[0062] The L-carnitine and thymol cocrystal prepared in Example 1 was subjected to differential scanning calorimetry analysis. Figure 2 is the differential scanning calorimetry analysis diagram of L-carnitine and thymol cocrystal in Example 1, Figure 2 It can be seen that the co-crystal of L-carnitine and thymol has an endothermic peak at about 139°C.

[0063] The L-carnitine and thymol cocrystal prepared in Example 1 was analyzed by Fourier transform infrared spectroscopy. Figure 3 is the Fourier transform infrared spectrum of L-carnitine and thymol cocrystal in Example 1, Figure 3 It can be seen that the cocrystal of L-carnitine and thymol is at 3460 cm -1 、3386cm -1 、3180cm -1 、3033cm -1 、2961cm -1 、2921cm -1 、2797cm -1 、2747cm -1 、2725cm -1 、2662cm -1 、2613cm -1 、2492cm -1 、1601cm -1 、1480cm -1 、1443cm -1 、1393cm -1 、1339cm -1 、1291cm -1 、1270cm -1 、1188cm -1 、1154cm -1 、1091cm-1 、1061cm -1 、946cm -1 、899cm -1 、873cm -1 、805cm -1 、740cm -1 、596cm -1 There are characteristic peaks.

[0064] Example 2

[0065] In this embodiment, a L-carnitine and thymol co-crystal is prepared, and the steps are as follows:

[0066] 0.2 mmol of L-carnitine and 0.2 mmol of thymol were weighed and added to a 10 mL EP tube, 1 mL of n-heptane was added, and the mixture was stirred at 600 rpm for 24 h at room temperature. The suspension was filtered under reduced pressure, and the filter cake was dried at room temperature for 24 h to obtain a white powder of L-carnitine and thymol cocrystal.

[0067] The L-carnitine and thymol co-crystal prepared in Example 2 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 2:

[0068] Table 2 X-ray powder diffraction analysis data of L-carnitine and thymol cocrystal in Example 2

[0069]

[0070]

[0071] Example 3

[0072] In this embodiment, a L-carnitine and thymol co-crystal is prepared, and the steps are as follows:

[0073] Weigh 0.2 mmol of L-carnitine and 0.2 mmol of thymol into a 10 mL EP tube, add 5 μL of methyl tert-butyl ether and 1 mL of n-heptane mixed solution, and stir at 600 rpm for 12 h at room temperature. Filter the suspension under reduced pressure, and dry the filter cake at room temperature for 24 h to obtain a white powder of L-carnitine and thymol cocrystal.

[0074] The L-carnitine and thymol co-crystal prepared in Example 3 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 3:

[0075] Table 3 X-ray powder diffraction analysis data of L-carnitine and thymol cocrystal in Example 3

[0076]

[0077] Example 4

[0078] In this embodiment, a L-carnitine and thymol co-crystal is prepared, and the steps are as follows:

[0079] Weigh 0.2 mmol of L-carnitine and 0.2 mmol of thymol into a 10 mL EP tube, add 5 μL of ethyl acetate and 1 mL of n-heptane mixed solution, and stir at 600 rpm for 12 h at room temperature. Filter the suspension under reduced pressure, and dry the filter cake at room temperature for 24 h to obtain a white powder of L-carnitine and thymol cocrystal.

[0080] The L-carnitine and thymol co-crystal prepared in Example 4 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 4:

[0081] Table 4 X-ray powder diffraction analysis data of L-carnitine and thymol cocrystal of Example 4

[0082]

[0083]

[0084] Example 5

[0085] In this embodiment, a L-carnitine and thymol co-crystal is prepared, and the steps are as follows:

[0086] Weigh 0.2 mmol of L-carnitine and 0.2 mmol of thymol into a 10 mL EP tube, add 5 μL of acetone and 1 mL of n-heptane mixed solution, and stir at 600 rpm for 24 h at room temperature. Filter the suspension under reduced pressure, and dry the filter cake at room temperature for 24 h to obtain a white powder of L-carnitine and thymol cocrystal.

[0087] The L-carnitine and thymol co-crystal prepared in Example 5 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 5:

[0088] Table 5 X-ray powder diffraction analysis data of L-carnitine and thymol cocrystal of Example 5

[0089]

[0090] Example 6

[0091] In this embodiment, a L-carnitine and thymol co-crystal is prepared, and the steps are as follows:

[0092] Weigh 0.2 mmol of L-carnitine and 0.2 mmol of thymol into a 10 mL EP tube, add 5 μL of methanol and 1 mL of n-heptane mixed solution, and stir at 600 rpm for 24 h at room temperature. Filter the suspension under reduced pressure, and dry the filter cake at room temperature for 24 h to obtain a white powder of L-carnitine and thymol cocrystal.

[0093] The L-carnitine and thymol co-crystal prepared in Example 6 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 6:

[0094] Table 6 X-ray powder diffraction analysis data of L-carnitine and thymol cocrystal of Example 6

[0095]

[0096]

[0097] Example 7

[0098] In this embodiment, a L-carnitine and thymol co-crystal is prepared, and the steps are as follows:

[0099] Weigh 0.2 mol of L-carnitine and 0.2 mol of thymol and put them into a grinder. After grinding for 2 minutes, a white powder of L-carnitine and thymol cocrystal is obtained.

[0100] The L-carnitine and thymol co-crystal prepared in Example 7 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 7:

[0101] Table 7 X-ray powder diffraction analysis data of L-carnitine and thymol cocrystal of Example 7

[0102]

[0103] Example 8

[0104] This embodiment prepares a L-carnitine and thymol composition, the steps are:

[0105] 0.4 mmol of L-carnitine and 0.2 mmol of thymol were weighed and added into a 2 mL EP tube together with a steel ball with a diameter of 5 mm, and ground at a frequency of 20 Hz for 30 min to obtain a white powder of a composition of L-carnitine and thymol.

[0106] The L-carnitine and thymol composition prepared in Example 8 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 8:

[0107] Table 8 X-ray powder diffraction analysis data of the L-carnitine and thymol composition of Example 8

[0108]

[0109]

[0110] It can be seen from the X-ray powder diffraction analysis data in Table 8 that the L-carnitine and thymol composition has characteristic peaks of the above-mentioned L-carnitine and thymol co-crystal at 2θ angles of approximately 4.4°, 18.4°, 18.6°, 19.8°, and 21.8°, and has characteristic peaks of L-carnitine at 2θ angles of approximately 9.2°, 12.1°, 16.1°, and 24.4°, indicating that the composition is composed of L-carnitine and thymol co-crystals and L-carnitine.

[0111] Example 9

[0112] This embodiment prepares a L-carnitine and thymol composition, the steps are:

[0113] 0.6 mmol of L-carnitine and 0.2 mmol of thymol were weighed and added into a 2 mL EP tube together with a steel ball with a diameter of 5 mm, and ground at a frequency of 20 Hz for 30 min to obtain a white powder of a composition of L-carnitine and thymol.

[0114] The L-carnitine and thymol composition prepared in Example 9 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in the table:

[0115] Table 9 X-ray powder diffraction analysis data of the L-carnitine and thymol composition of Example 9

[0116]

[0117] It can be seen from the X-ray powder diffraction analysis data in Table 9 that the L-carnitine and thymol composition has characteristic peaks of the L-carnitine and thymol cocrystal at 2θ angles of approximately 4.3°, 18.3°, 18.7°, 19.7°, and 21.7°, and has characteristic peaks of L-carnitine at 2θ angles of approximately 9.1°, 11.9°, 16.1°, and 24.2°, indicating that the composition is composed of L-carnitine and thymol cocrystals and L-carnitine.

[0118] Example 10

[0119] This embodiment prepares a L-carnitine and thymol composition, the steps are:

[0120] 0.5 mmol of L-carnitine and 0.1 mmol of thymol were weighed, added into a 2 mL EP tube together with a steel ball with a diameter of 5 mm, and ground at a frequency of 20 Hz for 30 min to obtain a white powder of a composition of L-carnitine and thymol.

[0121] The L-carnitine and thymol composition prepared in Example 10 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 10:

[0122] Table 10 X-ray powder diffraction analysis data of the L-carnitine and thymol composition of Example 10

[0123]

[0124] It can be seen from the X-ray powder diffraction analysis data in Table 10 that the L-carnitine and thymol composition has characteristic peaks of the L-carnitine and thymol co-crystal at 2θ angles of approximately 4.4°, 15.7°, 18.3°, 18.6°, 19.8°, and 21.8°, and characteristic peaks of L-carnitine at 2θ angles of approximately 9.2°, 11.9°, 16.1°, and 24.2°, indicating that the composition is composed of L-carnitine and thymol co-crystals and L-carnitine.

[0125] Embodiment 11

[0126] In this embodiment, a co-crystal of L-carnitine and carvacrol is prepared by the following steps:

[0127] 2 mmol of L-carnitine and 2 mmol of carvacrol were weighed, added into a ball mill together with a steel ball with a diameter of 1 cm, and ground at a frequency of 20 Hz for 30 min to obtain a white powder of L-carnitine and carvacrol cocrystal.

[0128] The L-carnitine and carvacrol cocrystal prepared in Example 11 was subjected to X-ray powder diffraction analysis. Figure 4 is the X-ray powder diffraction pattern of the L-carnitine and carvacrol co-crystal in Example 11. The X-ray powder diffraction analysis data are shown in Table 11:

[0129] Table 11 X-ray powder diffraction analysis data of L-carnitine and carvacrol cocrystal of Example 11

[0130]

[0131]

[0132] The L-carnitine and carvacrol cocrystal prepared in Example 11 was subjected to differential scanning calorimetry analysis. Figure 5 is the differential scanning calorimetry analysis diagram of L-carnitine and carvacrol cocrystal in Example 11, Figure 5 It can be seen that the co-crystal of L-carnitine and carvacrol exhibits an endothermic peak at about 140°C.

[0133] The L-carnitine and carvacrol cocrystal prepared in Example 11 was analyzed by Fourier transform infrared spectroscopy. Figure 6 is the Fourier transform infrared spectrum of L-carnitine and carvacrol cocrystal in Example 11, Figure 6 It can be seen that the co-crystal of L-carnitine and carvacrol is at 3459 cm -1 、3174cm -1、3050cm -1 、3008cm -1 、2962cm -1 、2919cm -1 、2799cm -1 、2377cm -1 、2343cm -1 、2304cm -1 、1599cm -1 、1481cm -1 、1395cm -1 、1337cm -1 、1257cm -1 、1190em -1 、1150cm -1 、1108cm -1 、1051cm -1 、945cm -1 、874cm -1 、809cm -1 、772cm -1 、699cm -1 、626cm -1 、594cm -1 、560cm -1 There are characteristic peaks.

[0134] Example 12

[0135] In this embodiment, a co-crystal of L-carnitine and carvacrol is prepared by the following steps:

[0136] 0.2 mmol of L-carnitine and 0.2 mmol of carvacrol were weighed and added into a 2 mL EP tube together with a steel ball with a diameter of 5 mm, 5 μL of ethanol was added, and the mixture was ground at a frequency of 20 Hz for 30 min to obtain a white powder of L-carnitine and carvacrol cocrystal.

[0137] The L-carnitine and carvacrol co-crystal obtained in Example 12 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 12:

[0138] Table 12 X-ray powder diffraction analysis data of L-carnitine and carvacrol cocrystal of Example 12

[0139]

[0140] Example 13

[0141] In this embodiment, a co-crystal of L-carnitine and carvacrol is prepared by the following steps:

[0142] 0.2 mmol of L-carnitine and 0.2 mmol of carvacrol were weighed and added into a 2 mL EP tube together with a steel ball with a diameter of 5 mm, 5 μL of isopropyl acetate was added, and the mixture was ground at a frequency of 20 Hz for 30 min to obtain a white powder of L-carnitine and carvacrol cocrystal.

[0143] The L-carnitine and carvacrol cocrystal obtained in Example 13 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 13:

[0144] Table 13 X-ray powder diffraction analysis data of L-carnitine and carvacrol cocrystal of Example 13

[0145]

[0146] Embodiment 14

[0147] In this embodiment, a co-crystal of L-carnitine and carvacrol is prepared by the following steps:

[0148] 0.2 mmol of L-carnitine and 0.2 mmol of carvacrol were weighed and added into a 2 mL EP tube together with a steel ball with a diameter of 5 mm, 5 μL of isopropanol was added, and the mixture was ground at a frequency of 20 Hz for 30 min to obtain a white powder of L-carnitine and carvacrol cocrystal.

[0149] The L-carnitine and carvacrol co-crystal obtained in Example 14 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 14:

[0150] Table 14 X-ray powder diffraction analysis data of L-carnitine and carvacrol cocrystal of Example 14

[0151]

[0152] Embodiment 15

[0153] In this embodiment, a co-crystal of L-carnitine and carvacrol is prepared by the following steps:

[0154] 0.2 mmol of L-carnitine and 0.2 mmol of carvacrol were weighed and added to a 10 mL EP tube, 1 mL of n-hexane was added, and the mixture was stirred at 600 rpm for 4 h at room temperature. The suspension was filtered under reduced pressure, and the filter cake was dried at room temperature for 24 h to obtain a white powder of L-carnitine and carvacrol cocrystal.

[0155] The L-carnitine and carvacrol cocrystal obtained in Example 15 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 15:

[0156] Table 15 X-ray powder diffraction data of L-carnitine and carvacrol cocrystal of Example 15

[0157]

[0158] Example 16

[0159] In this embodiment, a co-crystal of L-carnitine and carvacrol is prepared by the following steps:

[0160] 0.2 mmol of L-carnitine and 0.2 mmol of carvacrol were weighed and added to a 10 mL EP tube, 1 mL of isopropanol was added, and the mixture was stirred at 600 rpm for 12 h at room temperature. The suspension was filtered under reduced pressure, and the filter cake was dried at room temperature for 24 h to obtain a white powder of L-carnitine and carvacrol cocrystal.

[0161] The L-carnitine and carvacrol cocrystal obtained in Example 16 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 16:

[0162] Table 16 X-ray powder diffraction analysis data of L-carnitine and carvacrol cocrystal of Example 16

[0163]

[0164] Embodiment 17

[0165] In this embodiment, a co-crystal of L-carnitine and carvacrol is prepared by the following steps:

[0166] Weigh 0.2 mol of L-carnitine and 0.2 mol of carvacrol into a grinder, and grind for 2 minutes to obtain a white powder of L-carnitine and carvacrol cocrystal.

[0167] The L-carnitine and carvacrol cocrystal obtained in Example 17 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 17:

[0168] Table 17 X-ray powder diffraction analysis data of L-carnitine and carvacrol cocrystal of Example 17

[0169]

[0170] Embodiment 18

[0171] This embodiment prepares a L-carnitine and carvacrol composition, the steps are:

[0172] 0.4 mmol of L-carnitine and 0.2 mmol of carvacrol were weighed, added into a 2 mL EP tube together with a steel ball with a diameter of 5 mm, and ground at a frequency of 20 Hz for 30 min to obtain a white powder of a composition of L-carnitine and carvacrol.

[0173] The L-carnitine and carvacrol composition prepared in Example 18 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 18:

[0174] Table 18 X-ray powder diffraction analysis data of the L-carnitine and carvacrol composition of Example 18

[0175]

[0176]

[0177] It can be seen from the X-ray powder diffraction analysis data in Table 18 that the L-carnitine and carvacrol composition has characteristic peaks of the above-mentioned L-carnitine and carvacrol co-crystals at 2θ angles of approximately 4.5°, 18.3°, 18.8°, 19.2°, 19.9°, and 23.2°, and characteristic peaks of L-carnitine at 2θ angles of approximately 9.2°, 11.9°, 16.2°, 24.3°, and 28.1°, indicating that the composition is composed of L-carnitine and carvacrol co-crystals and L-carnitine.

[0178] Embodiment 19

[0179] This embodiment prepares a L-carnitine and carvacrol composition, the steps are:

[0180] 0.6 mmol of L-carnitine and 0.2 mmol of carvacrol were weighed, added into a 2 mL EP tube together with a steel ball with a diameter of 5 mm, and ground at a frequency of 20 Hz for 30 min to obtain a white powder of a composition of L-carnitine and carvacrol.

[0181] The L-carnitine and carvacrol composition prepared in Example 19 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 19:

[0182] Table 19 X-ray powder diffraction analysis data of the L-carnitine and carvacrol composition of Example 19

[0183]

[0184]

[0185] It can be seen from the X-ray powder diffraction analysis data in Table 19 that the L-carnitine and carvacrol composition has characteristic peaks of the above-mentioned L-carnitine and carvacrol co-crystals at 2θ angles of approximately 4.4°, 18.3°, 18.7°, 19.2°, 19.8°, and 23.2°, and has characteristic peaks of L-carnitine at 2θ angles of approximately 9.1°, 11.9°, 16.1°, 24.2°, and 28.1°, indicating that the composition is composed of L-carnitine and carvacrol co-crystals and L-carnitine.

[0186] Embodiment 20

[0187] This embodiment prepares a L-carnitine and carvacrol composition, the steps are:

[0188] 0.5 mmol of L-carnitine and 0.1 mmol of carvacrol were weighed, added into a 2 mL EP tube together with a steel ball with a diameter of 5 mm, and ground at a frequency of 20 Hz for 30 min to obtain a white powder of a composition of L-carnitine and carvacrol.

[0189] The L-carnitine and carvacrol composition prepared in Example 20 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 20:

[0190] Table 20 X-ray powder diffraction analysis data of the L-carnitine and carvacrol composition of Example 20

[0191]

[0192] It can be seen from the X-ray powder diffraction analysis data in Table 20 that the L-carnitine and carvacrol composition has characteristic peaks of the above-mentioned L-carnitine and carvacrol co-crystals at 2θ angles of approximately 4.4°, 18.3°, 18.6°, 19.1°, 19.9°, and 23.4°, and characteristic peaks of L-carnitine at 2θ angles of approximately 9.1°, 16.1°, 24.3°, and 28.1°, indicating that the composition is composed of L-carnitine and carvacrol co-crystals and L-carnitine.

[0193] Embodiment 21

[0194] This embodiment prepares a L-carnitine and carvacrol composition, the steps are:

[0195] 0.9 mmol of L-carnitine and 0.1 mmol of carvacrol were weighed, added into a 2 mL EP tube together with a steel ball with a diameter of 5 mm, and ground at a frequency of 20 Hz for 30 min to obtain a white powder of a composition of L-carnitine and carvacrol.

[0196] The L-carnitine and carvacrol composition prepared in Example 21 was subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 21:

[0197] Table 21 X-ray powder diffraction analysis data of the L-carnitine and carvacrol composition of Example 21

[0198]

[0199] It can be seen from the X-ray powder diffraction analysis data in Table 21 that the L-carnitine and carvacrol composition has characteristic peaks of the above-mentioned L-carnitine and carvacrol co-crystals at 2θ angles of approximately 4.4°, 18.3°, 18.8°, 19.1°, and 19.8°, and characteristic peaks of L-carnitine at 2θ angles of approximately 9.1°, 11.9°, 16.1°, and 24.2°, indicating that the composition is composed of L-carnitine and carvacrol co-crystals and L-carnitine.

[0200] Embodiment 22

[0201] In this embodiment, a co-crystal of L-carnitine, thymol and carvacrol is prepared by the following steps:

[0202] Weigh 0.4mmol L-carnitine, 0.2mmol thymol, and 0.2mmol carvacrol into a 10mL EP tube, add 5μL methanol and 1mL n-heptane mixed solution, and stir at 600rpm for 6h at room temperature. Filter the suspension under reduced pressure, and dry the filter cake at room temperature for 24h to obtain a white powder of L-carnitine, thymol, and carvacrol cocrystals.

[0203] X-ray powder diffraction analysis was performed on the co-crystal of L-carnitine, thymol and carvacrol obtained in Example 22. Figure 7 This is the X-ray powder diffraction pattern of the co-crystal of L-carnitine, thymol and carvacrol in Example 22. The X-ray powder diffraction analysis data are shown in Table 22:

[0204] Table 22 X-ray powder diffraction analysis data of L-carnitine, thymol and carvacrol cocrystals of Example 22

[0205]

[0206] Embodiment 23

[0207] In this embodiment, a co-crystal of L-carnitine, thymol and carvacrol is prepared by the following steps:

[0208] 3 mmol of L-carnitine, 1 mmol of thymol, and 2 mmol of carvacrol were weighed, and added into a ball mill together with a steel ball with a diameter of 1 cm, and ground at a frequency of 20 Hz for 30 min to obtain a white powder of cocrystal of L-carnitine, thymol and carvacrol.

[0209] The L-carnitine, thymol and carvacrol co-crystals prepared in Example 23 were subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 23:

[0210] Table 23 X-ray powder diffraction analysis data of L-carnitine, thymol and carvacrol cocrystals of Example 23

[0211]

[0212] Embodiment 24

[0213] In this embodiment, a co-crystal of L-carnitine, thymol and carvacrol is prepared by the following steps:

[0214] 3 mmol of L-carnitine, 2 mmol of thymol, and 1 mmol of carvacrol were weighed, and added into a ball mill together with a steel ball with a diameter of 1 cm, and ground at a frequency of 20 Hz for 30 min to obtain a white powder of L-carnitine, thymol and carvacrol cocrystals.

[0215] The L-carnitine, thymol and carvacrol co-crystals prepared in Example 24 were subjected to X-ray powder diffraction analysis. The X-ray powder diffraction analysis data are shown in Table 24:

[0216] Table 24 X-ray powder diffraction analysis data of L-carnitine, thymol and carvacrol cocrystals of Example 24

[0217]

[0218] In addition, the present invention also attempts to react the active ingredients of plant essential oils such as thymol and carvacrol with other amino acids, such as leucine, isoleucine, histidine, methionine, phenylalanine, threonine, tryptophan, valine, etc. through eutectic technology, and it is found that they are unable to form eutectics with the active ingredients of plant essential oils such as thymol and carvacrol.

[0219] Hygroscopicity evaluation

[0220] The powder samples of L-carnitine and thymol cocrystal prepared in Example 1 and L-carnitine and carvacrol cocrystal prepared in Example 11 were ground and passed through 100 mesh and 200 mesh sieves respectively, and the particle size was controlled to be 75 μm-150 μm, and L-carnitine with the same particle size was used as a comparison. The DVS Intrinsic dynamic moisture adsorption instrument of SMS Company of the United Kingdom was used, the temperature was kept constant at 25°C, and then the relative humidity was controlled to run from 40% to 90%, and the mass change of each relative humidity sample after the moisture absorption and weight gain reached equilibrium was recorded. The experimental results are shown in Table 25.

[0221] Table 25 Hygroscopicity evaluation results of cocrystal and L-carnitine

[0222]

[0223]

[0224] Table 25 shows the evaluation results of the hygroscopicity of the cocrystals and L-carnitine in Example 1 and Example 11. It can be seen from Table 25 that pure L-carnitine has strong hygroscopicity. In the process of increasing the relative humidity from 40% to 90%, the weight gain percentage of L-carnitine increased from 43.50% to 150.13%, and deliquescence occurred. When the relative humidity reached 90%, the weight gain percentages of the L-carnitine and thymol cocrystals in Example 1 and the L-carnitine and carvacrol cocrystals in Example 11 were 69.68% and 68.35%, respectively, which were much lower than the weight gain percentage of pure L-carnitine at 90% relative humidity, and were similar to the weight gain percentage of pure L-carnitine at 60% relative humidity. It can be seen that after L-carnitine and thymol or carvacrol form cocrystals, their hygroscopicity is greatly reduced.

[0225] Stability evaluation

[0226] The powder samples of L-carnitine and thymol co-crystal prepared in Example 1 and L-carnitine and carvacrol co-crystal prepared in Example 11 were ground and passed through 100 mesh and 200 mesh sieves respectively to control the particle size to be 75 μm-150 μm. The above powder samples were sealed in PV bags and placed under long-term stability conditions of 25°C / 60%RH. The crystal phases were detected by X-ray powder diffraction analysis after 1 month, 2 months, 3 months and 6 months, respectively. The experimental results are shown in Table 26. The crystal phases of L-carnitine and thymol co-crystals and L-carnitine and carvacrol co-crystals can be stable for 6 months. It can be seen that L-carnitine and thymol co-crystals and L-carnitine and carvacrol co-crystals have good stability.

[0227] Table 26 Results of long-term stability test at 25°C / 60%RH

[0228]

[0229] Volatility evaluation

[0230] The powder samples of L-carnitine and thymol co-crystals prepared in Example 1 and L-carnitine and carvacrol co-crystals prepared in Example 11 were ground and passed through 100 mesh and 200 mesh sieves respectively to control the particle size to be 75 μm-150 μm. 100.0 mg of powder samples of L-carnitine and thymol co-crystals, L-carnitine and carvacrol co-crystals, free thymol and free carvacrol were weighed respectively, placed in a 10 mL glass beaker, and placed in an open thermostat (30°C ± 0.4°C). They were weighed at 1, 3, 5, 7, 10, 20 and 30 days, and each test was repeated three times. The sample volatility evaluation curve was drawn with time as the horizontal axis and mass as the vertical axis. Figure 8It can be seen that free thymol and free carvacrol volatilize rapidly, with 2.3% and 24.9% of their masses remaining respectively within 3 days, and both completely volatilize within 10 days. In contrast, the volatilization rate of L-carnitine and thymol cocrystals and L-carnitine and carvacrol cocrystals is significantly reduced, with the remaining masses of the two being 87.9% and 86.9% on the 10th day, respectively. On the 30th day, the remaining masses of the two are 83.9% and 81.8%, respectively. This indicates that the L-carnitine and thymol cocrystals and L-carnitine and carvacrol cocrystals prepared by the present invention have lower volatility and a longer retention time of the active ingredients.

[0231] Antibacterial test

[0232] The powder samples of L-carnitine and thymol cocrystal prepared in Example 1 and L-carnitine and carvacrol cocrystal prepared in Example 11 were ground and passed through 100 mesh and 200 mesh sieves respectively to control the particle size to be 75 μm-150 μm. Thymol, carvacrol, L-carnitine and thymol cocrystal powder samples and L-carnitine and carvacrol cocrystal powder samples were prepared into 4.0, 2.0, 1.0, 0.50, 0.25, 0.125, 0.06, 0.03 mg / mL standard solutions by microdilution method, and Escherichia coli, Staphylococcus aureus, Candida albicans, Salmonella enteritidis, and Aspergillus niger were taken as antibacterial objects. The determination of the minimum inhibitory concentration was carried out according to the micro-broth method recommended by the American Clinical and Laboratory Standards Association: the above solutions of different concentrations were added to a 96-well plate, and each well finally contained 100 μL of plant essential oil active ingredient / plant essential oil active ingredient eutectic dilution and 100 μL of diluted bacterial suspension with a concentration of 5×105 cfu / mL, which was placed in a 37°C incubator for 24 hours, and each group of tests was repeated 3 times. The minimum antibacterial concentration for sterile growth was recorded as the MIC value, and its ultraviolet absorption OD value was determined by an enzyme marker. The experimental results are shown in Table 27.

[0233] Table 27 Minimum inhibitory concentration (MIC-mg / mL) of active ingredients in plant essential oils and their co-crystals

[0234]

[0235] Table 27 shows the minimum inhibitory concentrations of the active ingredients of plant essential oils and their cocrystals. It can be seen from Table 27 that compared with the free active ingredients of plant essential oils, the cocrystals have lower minimum inhibitory concentrations against Escherichia coli, Candida albicans, Salmonella enteritidis, and Aspergillus niger, while the minimum inhibitory concentrations against Staphylococcus aureus are comparable. This indicates that the cocrystals have better antibacterial effects than the free active ingredients of plant essential oils.

[0236] Antibacterial test of tomato juice

[0237] Thymol and the L-carnitine and thymol cocrystal in Example 1 were selected to compare their antibacterial effects on Escherichia coli in tomato juice. Fresh tomatoes were selected, cleaned and peeled, and tomato juice was extracted using a juicer. The extracted tomato juice was filtered and the residue was removed to obtain clarified tomato juice. The tomato juice was pasteurized (65°C, 30min) and then inoculated with Escherichia coli and stored at 4°C. The tomato juice was treated with three different methods: 1) Control group: no antibacterial substances were added; 2) Experimental group 1: free thymol was added to tomato juice (concentration of 0.125 mg / mL); 3) Experimental group 2: L-carnitine and thymol cocrystal in Example 1 was added to tomato juice (concentration of 0.25 mg / mL, of which the concentration of thymol was 0.125 mg / mL). On days 0, 1, 3, and 5, the number of Escherichia coli in tomato juice was determined by plate colony counting method.

[0238] Fig. 9 This is a comparison of the inhibitory effects of free thymol, L-carnitine and thymol co-crystal on Escherichia coli in tomato juice. Fig. 9 It can be seen that at all time points, the number of Escherichia coli is ranked as follows: control group > experimental group 1 > experimental group 2. This indicates that the antibacterial effect of L-carnitine and thymol cocrystal on Escherichia coli is significantly better than that of free thymol. This indicates that the antibacterial effect of the cocrystal prepared by the present invention is significantly better than that of the free active ingredient of plant essential oil.

[0239] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be thought of by any technician familiar with the field within the technical scope disclosed by the present invention without creative work should be covered within the protection scope of the present invention.

Claims

1. A eutectic, characterized in that: The preparation method comprises the following raw materials: L-carnitine and active ingredients of plant essential oil; the molar ratio of the L-carnitine to the active ingredients of the plant essential oil is 1:1; and the active ingredients of the plant essential oil are at least one of thymol and carvacrol.

2. The L-carnitine and plant essential oil active ingredient eutectic according to claim 1, characterized in that: The co-crystal has diffraction peaks at 2θ values ​​of 4.4±0.2°, 18.3±0.2°, 18.8±0.2°, 19.9±0.2°, and 21.9±0.2° in the X-ray powder diffraction spectrum.

3. The co-crystal according to claim 2, when the active ingredient of the plant essential oil is thymol, the co-crystal is a co-crystal of L-carnitine and thymol; the co-crystal of L-carnitine and thymol also has at least one diffraction peak at 2θ values ​​of 13.7±0.2°, 14.5±0.2°, 15.5±0.2°, 24.7±0.2°, 25.7±0.2°, and 27.0±0.2° in the X-ray powder diffraction spectrum.

4. The co-crystal according to claim 2, when the active ingredient of the plant essential oil is carvacrol, the co-crystal is a L-carnitine and carvacrol co-crystal; the L-carnitine and carvacrol co-crystal also has at least one diffraction peak at 2θ values ​​of 5.7±0.2°, 13.2±0.2°, 14.1±0.2°, 15.0±0.2°, 17.6±0.2°, 19.2±0.2°, 20.4±0.2°, 23.3±0.2°, and 28.5±0.2° in the X-ray powder diffraction spectrum.

5. The eutectic according to claim 2, wherein: When the active ingredients of the plant essential oil are thymol and carvacrol, the co-crystal is a co-crystal of L-carnitine, thymol and carvacrol; the molar ratio of thymol to carvacrol is 1:(0.5-2); the co-crystal of L-carnitine, thymol and carvacrol also has at least one diffraction peak at 2θ values ​​of 5.7±0.2°, 13.7±0.2°, 14.5±0.2°, 17.6±0.2°, 23.3±0.2°, 24.7±0.2°, and 25.7±0.2° in the X-ray powder diffraction spectrum.

6. The method for preparing a co-crystal according to any one of claims 1 to 5, characterized in that: The preparation method comprises any one of the following two methods: Method 1: mixing the L-carnitine with the active ingredient of plant essential oil under solvent conditions, and collecting the solid by solid-liquid separation to obtain the co-crystal; Method 2: Applying mechanical force to make the L-carnitine contact and react with the active ingredient of plant essential oil to obtain the co-crystal.

7. The preparation method according to claim 6, wherein: In the method 2, the device for applying mechanical force is selected from a ball mill, a pulverizer, a mixer, an extruder or a stirring device.

8. A composition comprising the cocrystal according to any one of claims 1 to 5 and free L-carnitine, wherein: The molar ratio of L-carnitine to the active ingredients of plant essential oil is (1-9):

1.

9. A product comprising the co-crystal according to any one of claims 1 to 5 or the composition according to claim 8.

10. The product according to claim 9, which is food, health care product, feed, daily chemical product or medicine.

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