Preparation method of 13-cis astaxanthin product

Abstract

The invention discloses a preparation method of a 13-cis astaxanthin product, which comprises the following steps: S1, carrying out thermal isomerization reaction on all-trans astaxanthin to obtain an astaxanthin isomer mixture; and S2, mixing the astaxanthin isomer mixture obtained in the step S1 with an extraction agent, extracting, filtering to obtain filtrate, and removing the extraction agent to obtain the 13-cis-astaxanthin product, the reaction temperature of the thermal isomerization reaction in the step S1 is 120-200 DEG C, and the reaction time is 40-80 minutes; the extracting agent in the step S2 is an organic solvent or a mixed solvent of the organic solvent and water, and the volume ratio of the organic solvent to the water is larger than or equal to 2.3; the organic solvent is at least one of methanol, ethanol, propanol and acetonitrile. According to the method, the temperature and the time of the astaxanthin thermal isomerization reaction are controlled, the specific extraction agent is used for extracting the reaction product, the product rich in 13-cis-astaxanthin is efficiently prepared, and the method is simple, convenient, suitable for large-scale production and capable of being widely applied to the fields of food and medicine raw materials.

Description

Technical Field

[0001] This invention relates to the field of food or pharmaceutical raw material preparation technology, and more specifically, to a method for preparing a 13-cis-astaxanthin product. Background Technology

[0002] Astaxanthin (3,3'-dihydroxy-4,4'-diketo-β,β'-carotene) is a ketocarotenoid with extremely strong antioxidant activity and wide applications in food, health products, cosmetics, and pharmaceuticals. The conjugated double bond system in the astaxanthin molecule results in various geometric isomers, primarily determined by the cis-trans configuration of the double bonds. Common astaxanthin isomers include the all-trans isomer. E -AST), 9-cis(9 Z -AST), 13-cis(13) Z -AST) and 15-cis(15 Z Astaxanthin from natural sources (such as Haematococcus pluvialis or krill) is usually predominantly in the thermodynamically stable all-trans configuration, which can account for more than 90% of the total astaxanthin.

[0003] Recent scientific research has shown that astaxanthin with different geometric configurations exhibits significant differences in physicochemical properties and bioavailability. For example, cis-astaxanthin ( Z Compared to all-trans astaxanthin, 13-AST exhibits higher antioxidant activity, bioavailability, and tissue targeting. Among them, 13-cis-astaxanthin (13... Z -AST has been shown to have significant advantages over all-trans and other cis isomers in terms of free radical scavenging, cellular-level antioxidant activity, inhibition of inflammatory factors, in vitro digestion and absorption, improved bioavailability, and tissue distribution enrichment. However, astaxanthin... E / Z Isomerization reactions are typically reversible and dynamic, and in this reaction, 13- Z AST exhibits lower selectivity compared to other cis isomers, making it difficult to increase its content in the product. This hinders the development of high 13- Z The preparation of astaxanthin products with AST content has presented technical challenges.

[0004] Existing technologies typically first utilize thermal or photo-induced isomerization to prepare products containing... Z -AST astaxanthin mixture, then separated from it by chromatographic or column chromatography and other methods 13- Z AST. For example, Zhou Lesong et al. (2025) of South China Agricultural University obtained a mixture of astaxanthin with a cis isomer mass ratio of 31% by photoinduced isomerization, and then obtained a high content of 13- AST by column chromatography. ZAST. However, although this method yielded 13- Z While AST content is high, the separation process is cumbersome, time-consuming, and costly, making it difficult to apply to large-scale production. Summary of the Invention

[0005] To address the issue that existing astaxanthin products cannot simultaneously achieve high 13-cis-astaxanthin content and scalable production, this invention provides a method for preparing 13-cis-astaxanthin products, which can achieve 13-cis-astaxanthin content through simple and rapid steps. Z The efficient separation by AST not only increased the content of 13-cis-astaxanthin in astaxanthin products, but also significantly improved the content of high-13- Z The preparation efficiency of astaxanthin products with high AST content can be applied to high 13- Z Large-scale production of astaxanthin products with AST content.

[0006] Another object of the present invention is to provide a 13-cis-astaxanthin product prepared by the above-described preparation method.

[0007] The above-mentioned objective of this invention is achieved through the following technical solution: This invention also protects a method for preparing a 13-cis-astaxanthin product, comprising the following steps: S1. Astaxanthin undergoes a thermal isomerization reaction to obtain a mixture of astaxanthin isomers; S2. Mix the astaxanthin isomer mixture described in step S1 with the extractant, extract, filter and collect the filtrate, remove the extractant, and obtain the 13-cis-astaxanthin product. The thermal isomerization reaction in step S1 is carried out at a temperature of 120~200℃ for 40~80 min. The extractant in step S2 is an organic solvent, or a mixture of an organic solvent and water, wherein the volume ratio of the organic solvent to water is ≥2.3; the organic solvent is at least one of methanol, ethanol, propanol, and acetonitrile.

[0008] It should be noted that: The inventors of this invention discovered that, on the one hand, by controlling the reaction temperature and reaction time of the astaxanthin thermal isomerization reaction within a specific range, it is possible to generate 13- Z A higher proportion of AST results in a higher concentration of 13-cis-astaxanthin in the final product. Z The content of AST; on the other hand, due to 13- Z AST exhibits significantly higher solubility in specific organic solvents compared to other configurations of astaxanthin. Using these specific organic solvents as extractants to extract the astaxanthin isomer mixture obtained in step S1 can further enrich 13- ZAST, increasing the content of 13-cis-astaxanthin in 13- Z AST content.

[0009] The inventors of this invention have also discovered that the ratio of organic solvent to water is crucial when using a mixture of organic solvent and water as an extractant. As the organic solvent content in the extractant decreases, the 13- Z The content of AST first increases and then decreases, so the content of organic solvent in the extractant cannot be too low.

[0010] Preferably, the purity of the all-trans astaxanthin is ≥90%.

[0011] Preferably, the thermal isomerization reaction in step S1 is carried out in the presence of an organic solvent.

[0012] More preferably, the initial concentration of all-trans astaxanthin in the organic solvent is 1 to 2 mg / mL.

[0013] More preferably, the organic solvent is at least one of dichloromethane, acetone, and ethyl acetate.

[0014] Preferably, the reaction temperature of the thermal isomerization reaction is 140~200℃.

[0015] More preferably, the reaction temperature of the thermal isomerization reaction is 140~160°C.

[0016] More preferably, the reaction temperature of the thermal isomerization reaction is 160°C.

[0017] Preferably, the reaction time of the thermal isomerization reaction is 40-60 min.

[0018] More preferably, the reaction time of the thermal isomerization reaction is 50-60 min.

[0019] More preferably, the reaction time of the thermal isomerization reaction is 50 min.

[0020] More preferably, after the thermal isomerization reaction described in step S1, the step further includes the removal of the organic solvent.

[0021] More preferably, the method for removing the organic solvent is vacuum distillation.

[0022] More preferably, the temperature of the vacuum distillation is 35~45℃.

[0023] Preferably, the thermal isomerization reaction in step S1 is carried out in an inert gas atmosphere.

[0024] More preferably, the inert gas is at least one of nitrogen and argon.

[0025] Preferably, the extractant in step S2 is a mixture of organic solvent and water.

[0026] Preferably, the volume ratio of the organic solvent to water is ≥3.

[0027] More preferably, the volume ratio of the organic solvent to water is 3 to 19.

[0028] Preferably, the organic solvent used as the extractant in step S2 is at least one of ethanol and propanol; more preferably, it is ethanol.

[0029] More preferably, the propanol is isopropanol.

[0030] When a specific type of organic solvent is used as the extractant in step S2, the resulting 13-cis-astaxanthin product has a higher 13-ZAST content, and the extractant has lower toxicity and is more environmentally friendly.

[0031] Preferably, the extraction process in step S2 is as follows: sonication for 4-8 minutes, followed by standing for 50-100 minutes.

[0032] More preferably, the temperature for the settling period is 0~10°C.

[0033] More preferably, the settling is carried out under light-protected conditions.

[0034] Preferably, the filter membrane used in step S2 is an organic filter membrane.

[0035] Preferably, the pore size of the filter membrane used in step S2 is no greater than 0.3 μm.

[0036] More preferably, the filter membrane used in step S2 has a pore size of 0.22 μm.

[0037] Preferably, the method for removing the extractant in step S2 is vacuum concentration.

[0038] Preferably, after removing the extractant in step S2, a drying step is also included.

[0039] More preferably, the temperature for vacuum concentration is 35~40°C.

[0040] More preferably, the drying method is to first perform nitrogen blowing drying and then freeze drying.

[0041] This invention also protects a 13-cis-astaxanthin product prepared by the above-described method.

[0042] Compared with the prior art, the beneficial effects of the present invention are: This invention achieves efficient preparation of products rich in 13-cis-astaxanthin by controlling the temperature and time of the thermal isomerization reaction of astaxanthin and using a specific extractant to extract the reaction products. It is suitable for large-scale production and can be widely used in the food and pharmaceutical raw material fields. Attached Figure Description

[0043] Figures 1-15 The HPLC chromatograms are of the 13-cis-astaxanthin products prepared in Examples 1-15.

[0044] Figures 16-18 The HPLC chromatograms are of the 13-cis-astaxanthin products prepared in comparative examples 1-3. Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0046] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0047] Example 1 This embodiment provides a method for preparing a 13-cis-astaxanthin product, including the following steps: (1) Isomerization reaction: Weigh 100 mg of all-trans astaxanthin (Zhaoqing Juyuan, AS2024005, purity 98.7%), place it in the inner liner of a 100 mL hydrothermal reactor, add 100 mL of acetone, and shake gently to dissolve it, preparing a solution with a concentration of 1 mg / mL. Purge the inner liner with nitrogen gas for 30 seconds to replace the oxygen, and quickly install the inner liner into the reactor and seal it tightly. Place the reactor in an oven preheated to 160℃ and react for 40 minutes; (2) Separation and purification: After the reaction was completed, the reaction vessel was cooled to room temperature and slowly opened. The reaction solution was transferred to a round-bottom flask and the acetone solvent was removed by vacuum distillation at 40 °C. 10 mL of extractant (85% ethanol aqueous solution, hereinafter referred to as 85% ethanol; the same applies to other examples or comparative examples) was added to the obtained solid. The mixture was sonicated for 5 minutes and then allowed to stand in the dark at 4 °C for 1 hour. The mixture was filtered using a 0.22 μm organic filter membrane, and the filtrate was collected. The filtrate was concentrated to dryness under reduced pressure at 40 °C. The resulting product was dried under nitrogen and then lyophilized to obtain the 13-cis-astaxanthin product.

[0048] Examples 2-4 Examples 2-4 provide a series of methods for preparing 13-cis-astaxanthin products. The difference from Example 1 is that the reaction time of the isomerization reaction in step (1) is different, as shown in Table 1.

[0049] Examples 5-8 Examples 5-8 provide a series of methods for preparing 13-cis-astaxanthin products. The difference from Example 2 is that the reaction temperature of the isomerization reaction in step (1) is different, as shown in Table 1.

[0050] Examples 9-15 Examples 9-15 provide a series of methods for preparing 13-cis-astaxanthin products. The difference from Example 2 is that the type of extractant used in step (2) is different, as shown in Table 1.

[0051] Comparative Examples 1-2 Comparative Examples 1 and 2 provide a series of methods for preparing 13-cis-astaxanthin products. The difference from Example 2 is that the reaction time of the isomerization reaction in step (1) is different, as shown in Table 1.

[0052] Comparative Example 3 Comparative Example 3 provides a method for preparing a 13-cis-astaxanthin product, which differs from Example 2 in that the reaction temperature of the isomerization reaction in step (1) is different, as shown in Table 1.

[0053] Table 1. Reaction time, reaction temperature, and type of extractant for each example and comparative example.

[0054] Sample characterization and performance testing High-performance liquid chromatography (HPLC) was used to detect 13- in the astaxanthin products of each example and comparative example. Z AST, Total Z The percentage of AST among all astaxanthin isomers is determined by the following steps: A small amount of sample was dissolved in methanol, filtered through a 0.22 μm organic filter membrane, and the 13-cis-astaxanthin content was analyzed by HPLC at a detection wavelength of 470 nm. Chromatographic conditions: C18 column (250 mm × 4.6 mm, 5 μm), column temperature 30℃, flow rate 1 mL / min, injection volume 10 μL, mobile phase methanol-water (92.5: 7.5, v / v), isocratic elution, qualitative analysis based on retention time, UV absorption spectrum, and Q value, and the 13-cis-astaxanthin content was calculated using the area normalization method. Z AST or total Z -Percentage of AST relative to total astaxanthin isomers.

[0055] Figures 1-18 The images show HPLC chromatograms of the 13-cis-astaxanthin products from each example and comparative example. The 13-cis ... ZAST, Total Z The proportion of -AST to all astaxanthin isomers is shown in Table 2.

[0056] Table 2. Astaxanthin products from each example and comparative example, containing 13- Z AST ratio and total Z -AST ratio

[0057] As can be seen from Table 2, the astaxanthin products of Examples 1-15 have a 13- Z The AST content was all above 47%, indicating that the preparation method provided by this invention successfully obtained 13- Z Astaxanthin products with high AST content.

[0058] The isomerization reaction times in Comparative Examples 1 and 2 were too short, and the isomerization reaction temperature in Comparative Example 3 was too high, resulting in the presence of 13- in the astaxanthin products obtained from the above comparative examples. Z The AST content is low.

[0059] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a 13-cis-astaxanthin product, characterized in that, It includes the following steps: S1. All-trans astaxanthin undergoes a thermal isomerization reaction to obtain a mixture of astaxanthin isomers; S2. Mix the astaxanthin isomer mixture described in step S1 with the extractant, extract, filter and collect the filtrate, remove the extractant, and obtain the 13-cis-astaxanthin product. The thermal isomerization reaction in step S1 is carried out at a temperature of 120~200℃ for 40~80 min. The extractant in step S2 is an organic solvent, or a mixture of an organic solvent and water, wherein the volume ratio of the organic solvent to water is ≥2.3; the organic solvent is at least one of methanol, ethanol, propanol, and acetonitrile.

2. The preparation method according to claim 1, characterized in that, The purity of the all-trans astaxanthin is ≥90%.

3. The preparation method according to claim 1, characterized in that, The thermal isomerization reaction described in step S1 is carried out in the presence of an organic solvent.

4. The preparation method according to claim 3, characterized in that, The initial concentration of all-trans astaxanthin in the organic solvent was 1-2 mg / mL.

5. The preparation method according to claim 3, characterized in that, The organic solvent is at least one of dichloromethane, acetone, and ethyl acetate.

6. The preparation method according to claim 1, characterized in that, The thermal isomerization reaction is carried out at a temperature of 140-200℃ for 40-60 minutes.

7. The preparation method according to claim 1, characterized in that, In the extractant described in step S2, the volume ratio of the organic solvent to water is ≥3.

8. The preparation method according to claim 1, characterized in that, The extraction process described in step S2 is as follows: sonicate for 4-8 minutes, then let stand for 50-100 minutes.

9. The preparation method according to claim 1, characterized in that, The pore size of the filter membrane used in step S2 is ≤0.3μm.

10. A 13-cis-astaxanthin product, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 9.

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