Purification method of lutein ester

Abstract

The invention discloses a lutein ester purification method, and belongs to the technical field of lutein ester purification, the purification method comprises the following steps: S1, lutein ester is roughly dissolved in an organic solvent to prepare a crude product solution; s2, loading the crude product solution to a chromatographic column containing a composite adsorbent, carrying out gradient elution, and collecting an eluent; s3, concentrating the eluent to obtain concentrated slurry, adding an anti-solvent for crystallization, filtering, washing and drying; the composite adsorbent in the step S2 is composed of silica gel and macroporous adsorption resin; in the step S2, gradient elution is performed by sequentially adopting a first eluent and a second eluent, and the first eluent is petroleum ether and ethyl acetate in a volume ratio of (10-20): 1; the second eluent is petroleum ether and ethyl acetate in a volume ratio of (2-5): 1. The purity of the lutein ester is finally improved to 99% or above, and the yield is up to 85% or above.

Description

Technical Field

[0001] This invention relates to the field of lutein ester purification technology, and more particularly to a method for purifying lutein esters. Background Technology

[0002] Lutein esters are important carotenoid fatty acid esters, mainly found in marigold flowers. In the human body, they can be hydrolyzed into lutein, a major pigment in the macular region of the retina. Lutein possesses important physiological functions such as anti-oxidation, blue light filtering, vision protection, and prevention of age-related macular degeneration, and is widely used in food, health products, pharmaceuticals, and feed additives.

[0003] Currently, in industry, crude lutein esters are mainly obtained from marigold flower granules through organic solvent extraction and saponification (or non-saponification). This crude lutein ester has a complex composition, containing large amounts of oils, waxes, free fatty acids, and other carotenoids and other impurities. Its purity is typically only between 5% and 20%, which cannot directly meet the needs of high-end applications. Purification of crude lutein esters is currently crucial to improving its product value.

[0004] Chinese Patent Publication No. CN101891664A discloses a method for purifying lutein esters. First, marigold oil extract is dissolved in ethyl acetate at 25℃-80℃ and stirred for 1-6 hours. The liquid obtained from hot filtration is then added to anhydrous ethanol and stirred at 20-70℃ for 0.5-5.0 hours to form a homogeneous solution. Next, the solution is cooled at -5℃-30℃ for 5-20 hours and filtered. The filter cake is then washed with a lower alcohol and vacuum dried to remove solvent residue, yielding the desired high-purity lutein esters. The lutein ester content is 70%-80%, and the total lutein ester yield is approximately 45-69%. Chinese Patent Publication No. CN106588732A discloses a method for purifying lutein esters from marigold oil, comprising the following steps: a. Dissolving marigold oil in 1-5 times its mass of an ether solvent and stirring to form a homogeneous solution x; b. Filtering solution x at 20℃-70℃, obtaining a filtrate, then adding deionized water to the filtrate, stirring for 0.5-5 hours, and filtering again to obtain crystals y; c. Washing crystals y with deionized water until the deionized water flowing out after washing is colorless; d. Drying the crystals in a vacuum for 1-3 days after washing. The lutein ester content obtained by this invention is 75%-85%, and the yield is 72%-80%.

[0005] Currently, the yield and purity of lutein esters purified from crude lutein esters derived from marigold flowers are unsatisfactory, indicating significant room for improvement. Developing a purification method for lutein esters that can simultaneously achieve high purity and high yield has important industrial application value. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention discloses a purification method for lutein esters. This purification method achieves efficient purification of crude lutein esters through the coupling of a specific adsorbent combination, gradient elution, and crystallization process. The final product purity can reach over 99%, and the yield exceeds 85%.

[0007] To achieve the above objectives, the present invention adopts the following technical solution.

[0008] This invention provides a method for purifying lutein esters, comprising the following steps: S1, lutein esters are crudely dissolved in an organic solvent to prepare a crude solution; S2. Load the crude product solution onto a chromatography column containing a composite adsorbent, elute with gradient, and collect the eluent. S3. The eluent is concentrated to obtain a concentrated slurry, which is then crystallized by adding an antisolvent, filtered, washed, and dried.

[0009] In some embodiments, the organic solvent in step S1 is petroleum ether and / or n-hexane.

[0010] In some embodiments, the concentration of the crude product solution in step S1 is 50-150 mg / mL; preferably 115-135 mg / mL.

[0011] In some embodiments, the composite adsorbent in step S2 is composed of silica gel and macroporous adsorption resin. Preferably, the mass ratio of the silica gel to the macroporous adsorption resin is 3-1:1. Preferably, the macroporous adsorption resin is HPD-100 or AB-8 type resin.

[0012] In some embodiments, the height-to-diameter ratio of the chromatography column in step S2 is 10-15:1; preferably 11-13:1.

[0013] In some embodiments, the gradient elution in step S2 involves eluting with a first eluent and a second eluent sequentially. Preferably, the first eluent is a petroleum ether to ethyl acetate in a volume ratio of 10-20:1, more preferably 12-18:1; and the second eluent is a petroleum ether to ethyl acetate in a volume ratio of 2-5:1, more preferably 3-4:1. More preferably, the gradient elution involves eluting with the first eluent until the effluent is colorless, then eluting with the second eluent, collecting the orange-red eluent, until the effluent is colorless.

[0014] In some implementations, the concentration in step S3 is to concentrate the solution until it becomes viscous and a crystalline film forms on the surface.

[0015] In some embodiments, the volume ratio of the antisolvent to the concentrated slurry in step S3 is 3-5:1; preferably 4-5:1.

[0016] In some embodiments, the antisolvent in step S3 is a lower alcohol, preferably a C1-C4 alcohol, and more preferably methanol or ethanol.

[0017] In some embodiments, the crystallization in step S3 is performed by standing at 0-4°C for 4-8 hours; preferably, it is performed by standing at 1-3°C for 5-7 hours.

[0018] In some implementations, the washing in step S3 is a solvent wash at 0-4°C.

[0019] In some embodiments, the drying in step S3 is freeze drying, vacuum drying, or spray drying. Vacuum drying is preferred.

[0020] Compared with the prior art, the present invention has the following advantages: 1. Significantly Improved Purity and Yield: This invention cleverly combines the high separation efficiency of silica gel with the large adsorption capacity and anti-poisoning ability of macroporous adsorption resin through a composite adsorbent composed of silica gel and macroporous adsorption resin. By controlling the gradient elution parameters, efficient and clear separation of impurities and target products is achieved. Combined with an optimized crystallization process (antisolvent type, ratio, and crystallization temperature), the purity of lutein ester is ultimately increased to over 99%, with an overall yield exceeding 85%.

[0021] 2. Low cost and easy to scale up: The composite adsorbent and solvent used in this invention are all conventional chemical products, which are inexpensive and widely available. The chromatography column can be scaled up, and the overall process conditions are mild, making it very suitable for large-scale industrial production.

[0022] 3. High product quality: Because the process avoids strong acid, strong alkali or high temperature treatment, it effectively prevents the isomerization and degradation of lutein esters. The resulting product has a bright color (deep orange-red), low impurity residue and good stability.

[0023] 4. Green and environmentally friendly: The solvents used (petroleum ether, ethyl acetate, ethanol) have low toxicity and can be recycled and reused through distillation, which reduces production costs and environmental burden. Detailed Implementation

[0024] The following description of the embodiments is merely to aid in understanding the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of the claims. The following description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not limited to the embodiments shown herein, but can be applied to a wider scope consistent with the principles and novel features disclosed herein. While any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of the present invention, preferred methods and materials are listed herein.

[0025] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The crude lutein ester used in this invention is derived from marigold flowers, with an HPLC purity of 16.5%, and the silica gel is column chromatography silica gel (100-200 mesh).

[0026] Example 1 A method for purifying lutein esters, comprising the following steps: S1, crude lutein ester was dissolved in petroleum ether to prepare a crude solution of 50 mg / mL; S2. The crude solution is loaded onto a chromatography column (height-to-diameter ratio 10:1) containing a composite adsorbent (silica gel and HPD-100 macroporous adsorption resin in a mass ratio of 3:1) and then subjected to gradient elution. The first eluent (petroleum ether and ethyl acetate in a volume ratio of 10:1) is used for elution until the eluent is colorless. Then, the second eluent (petroleum ether and ethyl acetate in a volume ratio of 2:1) is used for elution. The orange-red eluent is collected until the eluent is colorless. S3. Concentrate the eluent until the solution becomes viscous and a crystal film forms on the surface. Add 3 times the volume of ethanol to the concentrated slurry and let it stand in a freezer at 0°C for 4 hours. Filter by suction, wash the crystals twice with pre-cooled (4°C) anhydrous ethanol, and dry the filter cake in a vacuum drying oven (35°C, -0.095 MPa) for 6 hours to obtain orange-red crystals.

[0027] Example 2 A method for purifying lutein esters, comprising the following steps: S1. Crude lutein ester was dissolved in n-hexane to prepare a crude solution of 150 mg / mL. S2. The crude solution is loaded onto a chromatography column (height-to-diameter ratio 15:1) containing a composite adsorbent (silica gel and HPD-100 macroporous adsorption resin in a mass ratio of 1:1) and then subjected to gradient elution. The first eluent (petroleum ether and ethyl acetate in a volume ratio of 20:1) is used for elution until the eluent is colorless. Then, the second eluent (petroleum ether and ethyl acetate in a volume ratio of 5:1) is used for elution. The orange-red eluent is collected until the eluent is colorless. S3. Concentrate the eluent until the solution becomes viscous and a crystal film forms on the surface. Add 5 times the volume of ethanol to the concentrated slurry and let it stand in a freezer at 4°C for 8 hours. Filter by suction, wash the crystals twice with pre-cooled (4°C) anhydrous ethanol, and dry the filter cake in a vacuum drying oven (35°C, -0.095 MPa) for 6 hours to obtain orange-red crystals.

[0028] Example 3 A method for purifying lutein esters, comprising the following steps: S1, crude lutein ester was dissolved in petroleum ether to prepare a crude solution of 125 mg / mL; S2. The crude solution is loaded onto a chromatography column (height-to-diameter ratio 12:1) containing a composite adsorbent (silica gel and HPD-100 macroporous adsorption resin in a mass ratio of 2:1) and then subjected to gradient elution. The first eluent (petroleum ether and ethyl acetate in a volume ratio of 15:1) is used for elution until the eluent is colorless. Then, the second eluent (petroleum ether and ethyl acetate in a volume ratio of 4:1) is used for elution. The orange-red eluent is collected until the eluent is colorless. S3. Concentrate the eluent until the solution becomes viscous and a crystal film forms on the surface. Add 4 times the volume of ethanol to the concentrated slurry and let it stand in a freezer at 2°C for 6 hours. Filter by suction, wash the crystals twice with pre-cooled (4°C) anhydrous ethanol, and dry the filter cake in a vacuum drying oven (35°C, -0.095 MPa) for 6 hours to obtain orange-red crystals.

[0029] Comparative Example 1 The difference between this comparative example and Example 3 is that the composite adsorbent in step S2 is silica gel, and the elution method is different.

[0030] Specifically, a method for purifying lutein esters includes the following steps: S1, crude lutein ester was dissolved in petroleum ether to prepare a crude solution of 125 mg / mL; S2. After loading the crude solution onto a chromatography column (height-to-diameter ratio 12:1) containing a composite adsorbent (silica gel), gradient elution is performed using eluent (petroleum ether and ethyl acetate in a volume ratio of 4:1). The orange-red eluent is collected until the effluent is colorless. S3. Concentrate the eluent until the solution becomes viscous and a crystal film forms on the surface. Add 4 times the volume of ethanol to the concentrated slurry and let it stand in a freezer at 2°C for 6 hours. Filter by suction, wash the crystals twice with pre-cooled (4°C) anhydrous ethanol, and dry the filter cake in a vacuum drying oven (35°C, -0.095 MPa) for 6 hours to obtain orange-red crystals.

[0031] Comparative Example 2 The difference between this comparative example and Example 3 is that the composite adsorbent in step S2 is different.

[0032] Specifically, a method for purifying lutein esters includes the following steps: S1, crude lutein ester was dissolved in petroleum ether to prepare a crude solution of 125 mg / mL; S2. The crude solution is loaded onto a chromatography column (height-to-diameter ratio 12:1) containing a composite adsorbent (HPD-100 macroporous adsorption resin) and then subjected to gradient elution. The first eluent (petroleum ether and ethyl acetate in a volume ratio of 15:1) is used for elution until the eluent is colorless. Then the second eluent (petroleum ether and ethyl acetate in a volume ratio of 4:1) is used for elution. The eluent is collected until the eluent is colorless. S3. Concentrate the eluent until the solution becomes viscous and a crystal film forms on the surface. Add 4 times the volume of ethanol to the concentrated slurry and let it stand in a freezer at 2°C for 6 hours. Filter by suction, wash the crystals twice with pre-cooled (4°C) anhydrous ethanol, and dry the filter cake in a vacuum drying oven (35°C, -0.095 MPa) for 6 hours to obtain orange-red crystals.

[0033] Comparative Example 3 The difference between this comparative example and Example 3 is that the mass ratio of silica gel and HPD-100 macroporous adsorption resin is different, as are the first eluent and the second eluent.

[0034] A method for purifying lutein esters, comprising the following steps: S1, crude lutein ester was dissolved in petroleum ether to prepare a crude solution of 125 mg / mL; S2. The crude solution is loaded onto a chromatography column (height-to-diameter ratio 12:1) containing a composite adsorbent (silica gel and HPD-100 macroporous adsorption resin in a mass ratio of 5:1) and then subjected to gradient elution. The first eluent (petroleum ether and ethyl acetate in a volume ratio of 18:1) is used for elution until the eluent is colorless. Then, the second eluent (petroleum ether and ethyl acetate in a volume ratio of 6:1) is used for elution. The orange-red eluent is collected until the eluent is colorless. S3. Concentrate the eluent until the solution becomes viscous and a crystal film forms on the surface. Add 4 times the volume of ethanol to the concentrated slurry and let it stand in a freezer at 2°C for 6 hours. Filter by suction, wash the crystals twice with pre-cooled (4°C) anhydrous ethanol, and dry the filter cake in a vacuum drying oven (35°C, -0.095 MPa) for 6 hours to obtain orange-red crystals.

[0035] Comparative Example 4 The difference between this comparative example and Example 3 is that the macroporous adsorption resin is different and the crystallization method is different.

[0036] A method for purifying lutein esters, comprising the following steps: S1, crude lutein ester was dissolved in petroleum ether to prepare a crude solution of 125 mg / mL; S2. The crude solution is loaded onto a chromatography column (height-to-diameter ratio 12:1) containing a composite adsorbent (silica gel and D-101 macroporous adsorption resin in a mass ratio of 2:1) and then subjected to gradient elution. The first eluent (petroleum ether and ethyl acetate in a volume ratio of 15:1) is used for elution until the eluent is colorless. Then the second eluent (petroleum ether and ethyl acetate in a volume ratio of 4:1) is used for elution. The orange-red eluent is collected until the eluent is colorless. S3. Concentrate the eluent until the solution becomes viscous and a crystal film forms on the surface. Add 4 times the volume of ethanol to the concentrated slurry and let it stand in a freezer at 6°C for 12 hours. Filter by suction, wash the crystals twice with pre-cooled (4°C) anhydrous ethanol, and dry the filter cake in a vacuum drying oven (35°C, -0.095 MPa) for 6 hours to obtain orange-red crystals.

[0037] The purity and yield results of the purification method are shown in Table 1.

[0038] Table 1

[0039] The results showed that the purification methods of Examples 1-3 of this invention yielded lutein esters with a purity of over 99% and a yield of over 85%, achieving high purity and high yield.

[0040] Comparing Comparative Example 4, it can be seen that using conventional adsorbents and crystallization methods, the purity of lutein esters after purification reaches over 95%, but the yield is less than 70%, failing to achieve both high purity and high yield. According to Comparative Examples 1-3, the yield of lutein esters after purification using conventional adsorbents and elution methods reaches over 70%, but the purity is low and cannot exceed 95%. Comparing Example 3 and Comparative Examples 1-4, it can be seen that the present invention, by combining composite adsorbents, elution methods, and crystallization steps, achieves unexpected technical effects in improving the purity and yield of lutein esters.

[0041] The foregoing description of the present invention is in conjunction with specific embodiments, but these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions to the details and form of the technical solutions of the present invention can be made without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

Claims

1. A method for purifying lutein esters, characterized in that, Includes the following steps: S1, lutein esters are crudely dissolved in an organic solvent to prepare a crude solution; S2. Load the crude product solution onto a chromatography column containing a composite adsorbent, elute with gradient, and collect the eluent. S3. The eluent is concentrated to obtain a concentrated slurry. An antisolvent is added and the mixture is allowed to stand at 0-4℃ for 4-8 hours to crystallize. The slurry is then filtered, washed, and dried. The composite adsorbent described in step S2 is composed of silica gel and HPD-100 macroporous adsorption resin in a mass ratio of 3-1:

1. The gradient elution in step S2 involves eluting with a first eluent and a second eluent in sequence. The first eluent is petroleum ether and ethyl acetate in a volume ratio of 10-20:1; the second eluent is petroleum ether and ethyl acetate in a volume ratio of 2-5:

1.

2. The purification method according to claim 1, characterized in that, The organic solvent mentioned in step S1 is petroleum ether and / or n-hexane.

3. The purification method according to claim 1, characterized in that, The concentration of the crude product solution in step S1 is 50-150 mg / mL.

4. The purification method according to claim 3, characterized in that, The concentration of the crude product solution in step S1 is 115-135 mg / mL.

5. The purification method according to claim 1, characterized in that, The height-to-diameter ratio of the chromatography column in step S2 is 10-15:

1.

6. The purification method according to claim 1, characterized in that, The gradient elution described in step S2 involves eluting with a first eluent until the effluent is colorless, then eluting with a second eluent, collecting the orange-red eluent, until the effluent is colorless.

7. The purification method according to claim 5, characterized in that, The first eluent is petroleum ether and ethyl acetate in a volume ratio of 12-18:1; the second eluent is petroleum ether and ethyl acetate in a volume ratio of 3-4:

1.

8. The purification method according to claim 1, characterized in that, The concentration mentioned in step S3 is to concentrate the solution until it becomes viscous and a crystal film forms on the surface of the liquid.

9. The purification method according to claim 1, characterized in that, The volume ratio of the antisolvent to the concentrated slurry in step S3 is 3-5:

1.

10. The purification method according to claim 9, characterized in that, The antisolvent mentioned in step S3 is a C1-C4 alcohol.

11. The purification method according to claim 10, characterized in that, The antisolvent mentioned in step S3 is methanol or ethanol.

12. The purification method according to claim 1, characterized in that, The crystallization described in step S3 involves standing at 1-3°C for 5-7 hours.

13. The purification method according to claim 10, characterized in that, The washing described in step S3 is washing with an anti-solvent at 0-4°C.

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