A dunaliella extract, a method for preparing the same, and use thereof in cosmetics

Abstract

This invention belongs to the field of cosmetic preparation technology, and discloses a Dunaliella salina extract, its preparation method, and its application in cosmetics. Dunaliella salina is prepared into a high-salt suspension. Deionized water is added dropwise to the high-salt suspension under stirring conditions, causing the NaCl mass-volume fraction to steadily decrease from 10%~20% to 3%~8%. Simultaneously, a surfactant, a co-surfactant, and an oil phase are added to obtain the extraction system. Stirring continues to form a semi-transparent emulsion. The resulting emulsion is separated and purified to obtain the high-salt Dunaliella salina extract. This invention utilizes only the osmotic pressure impact generated by gradient desalination to achieve in-situ cell wall disruption of Dunaliella salina, without any mechanical external force or enzymatic assistance. Furthermore, a microemulsion dispersion system is simultaneously constructed in-situ during the desalination process, achieving a continuous in-situ integrated process of desalination, emulsification, cell wall disruption, and extraction, shortening the process and improving efficiency.

Description

Technical Field

[0001] This invention belongs to the field of cosmetic preparation technology, specifically relating to a Dunaliella salina extract, its preparation method, and its application in cosmetics. Background Technology

[0002] Dunaliella salina, a halophilic microalga, is widely found in high-salt environments. Under extreme stress conditions, it can accumulate large amounts of carotenoids, glycerol, and various antioxidants, demonstrating significant environmental adaptability and bioactivity. Recent studies have shown that the β-carotene, astaxanthin, polyphenols, and other natural antioxidants abundant in Dunaliella salina extract exhibit good photostability and biocompatibility in the field of skin protection. β-carotene, in particular, can not only absorb some ultraviolet (UV) wavelengths but also effectively scavenge UV-induced reactive oxygen species (ROS), mitigating skin damage caused by photooxidation. Therefore, Dunaliella salina extract, as a natural, low-irritant, and multifunctional potential sunscreen auxiliary ingredient, shows broad application prospects in skin care and the development of natural sunscreen products.

[0003] Chinese Patent No. CN 109503448B discloses an industrial method for extracting and preparing high-content β-carotene from Dunaliella salina, comprising the following steps: 1) adding a non-polar solvent to Dunaliella salina powder for extraction to obtain an extract; 2) concentrating the extract and allowing it to crystallize to obtain a crystal layer and a solvent layer; 3) washing the crystal layer with water and drying it to obtain trans-β-carotene crystals; 4) concentrating the solvent layer to remove the solvent and obtaining Dunaliella salina oil, and removing impurities from the Dunaliella salina oil with supercritical fluid to obtain cis-β-carotene thick paste.

[0004] Chinese patent application CN117643738A discloses a process for preparing a high-proportion cis-carotene extract. The patent application uses Dunaliella salina powder as raw material, and the preparation process specifically includes steps such as extraction, extraction and column purification. The process is simple and conducive to industrialization, and the purity of the high-proportion cis-carotene extract obtained is greater than 50%.

[0005] However, existing Dunaliella salina extraction processes generally have the following drawbacks: (1) It requires pretreatment such as drying and pulverizing, which can easily cause the oxidative degradation of heat-sensitive active ingredients; (2) Extraction, cell wall breaking, and desalination are multi-step separation processes, which are lengthy, energy-intensive, and prone to contamination due to multiple material transfers; (3) The cell wall breaking and extraction are carried out in separate steps, which is a long process with multiple material transfers, easy to cause pollution and low efficiency; (4) The extraction system has poor compatibility with sunscreen cosmetic formulas, making subsequent compounding difficult. Summary of the Invention

[0006] In order to overcome the shortcomings and deficiencies of the existing technology, the primary objective of this invention is to provide a method for preparing Dunaliella salina extract; the method uses high-salt Dunaliella salina suspension as raw material, and simultaneously forms an emulsion in situ during continuous desalination, thereby achieving integrated cell wall breaking and extraction.

[0007] Another object of the present invention is to provide a Dunaliella salina extract prepared by the above preparation method.

[0008] Another object of the present invention is to provide the application of the above-mentioned Dunaliella salina extract.

[0009] The objective of this invention is achieved through the following technical solution: A method for preparing Dunaliella salina extract includes the following steps: (1) Raw material preparation: Add deionized water and NaCl to Dunaliella salina to prepare a high-salt Dunaliella salina suspension with a mass volume concentration of 100 g / L, wherein the mass volume fraction of NaCl in the high-salt Dunaliella salina suspension is 10%~20% (W / V). (2) Construction of in-situ continuous desalination and emulsification dispersion system: Under stirring conditions of 50 r / min, deionized water was added dropwise to the high-salt algae suspension obtained in step (1) at a rate of 0.5% per minute to reduce the mass volume fraction of NaCl from 10% to 20% to 3% to 8%; at the same time, surfactant, co-surfactant and oil phase were added sequentially, and each component was added dropwise within 5 min. The resulting reaction system was transferred to a high-pressure homogenizer and circulated 3 to 5 times under a pressure of 1200 to 1500 bar to form a semi-transparent emulsion; the amount of surfactant, co-surfactant and oil phase added accounted for 1% to 3%, 5% to 25% and 3% to 8% of the mass percentage of the reaction system, respectively. (3) Separation and purification: Centrifuge the emulsion obtained in step (2) at 8000~10000 r / min for 5~10 min and collect the supernatant; filter the supernatant through 5 μm, 1.2 μm and 0.45 μm microporous membranes in sequence and collect the filtrate to obtain the Dunaliella salina extract.

[0010] The surfactant in step (2) is one or more of Tween 20, Tween 60, Tween 80, PEG-20 hydrogenated castor oil, PEG-40 hydrogenated castor oil, and PEG-60 hydrogenated castor oil; the co-surfactant is one or more of ethanol, 1,2-propanol, 1,3-propanediol, 1,3-butanediol, and 1,2-hexanediol; and the oil phase is one or more of medium-chain triglycerides, isopropyl myristate, sunflower oil, corn oil, and jojoba oil.

[0011] An extract of Dunaliella salina prepared by the above-described preparation method.

[0012] The above-mentioned Dunaliella salina extract is used in the preparation of cosmetics with sun protection and antioxidant effects.

[0013] The principle of this invention: This invention involves highly dehydrating and shrinking Dunaliella salina under high-salt conditions (NaCl mass-volume fraction of 10%~20% (w / v)). Then, a slow gradient desalination is used to rapidly reduce the external osmotic pressure, allowing a large amount of water to enter the cells, causing the cell membrane to swell and rupture. At the same time, an emulsion is formed in situ, which encapsulates the carotenoids, fat-soluble antioxidants, and glycerol released from Dunaliella salina, thereby extracting them in situ. This achieves desalination, cell wall disruption, emulsification, and extraction in one step, without material transfer, and greatly simplifies the process.

[0014] The present invention has the following advantages and beneficial effects compared with the prior art: (1) The preparation process of the present invention does not require pretreatment, but directly uses high-salt Dunaliella salina suspension as raw material, saving the need for drying and pulverizing, reducing energy consumption and cost; the extraction process adopts a low-temperature non-destructive method, with low temperature and normal pressure throughout the process, and gentle treatment to avoid thermal degradation, thus significantly improving the retention rate of active ingredients; therefore, the method of the present invention overcomes the problem of activity loss caused by the traditional Dunaliella salina extraction process of drying, pulverizing and high-temperature treatment.

[0015] (2) The method of the present invention utilizes only the osmotic pressure impact generated by gradient desalination to achieve in-situ cell wall disruption of Dunaliella salina, without any mechanical external force or enzymatic hydrolysis assistance; and simultaneously constructs an emulsion system in situ during the desalination process, realizing the in-situ integrated continuous completion of the four steps of desalination, emulsification, cell wall disruption and extraction, shortening the process and improving efficiency.

[0016] (3) The preparation method of the present invention is green and safe, and the resulting extract has multiple functions such as sun protection, anti-oxidation and barrier repair, and is especially suitable for sun protection care. Attached Figure Description

[0017] Figure 1 This is an optical microscope (10×40x) image of the Dunaliella salina suspension after membrane rupture treatment in Example 1.

[0018] Figure 2 This is an optical microscope (10×40x) image of the Dunaliella salina suspension after membrane rupture treatment in Example 2.

[0019] Figure 3 This is an optical microscope (10×40x) image of the Dunaliella salina suspension after membrane rupture treatment in Example 3.

[0020] Figure 4 This is an optical microscope (10×40x) image of the Dunaliella salina suspension after membrane rupture treatment in Example 4.

[0021] Figure 5 This is an optical microscope (10×40x) image of the Dunaliella salina suspension after membrane rupture treatment in Example 5.

[0022] Figure 6 This is an optical microscope (10×40x) image of the Dunaliella salina suspension after membrane rupture treatment in Comparative Example 1.

[0023] Figure 7 This is an optical microscope (10×40x) image of the Dunaliella salina suspension after membrane rupture treatment in Comparative Example 2.

[0024] Figure 8 This is an optical microscope (10×40x) image of the Dunaliella salina suspension after membrane rupture treatment in Comparative Example 3.

[0025] Figure 9 This is an optical microscope (10×40x) image of the Dunaliella salina suspension after membrane rupture treatment in Comparative Example 4.

[0026] Figure 10 This is an optical microscope (10×40x) image of the Dunaliella salina suspension after membrane rupture treatment in Comparative Example 5.

[0027] Figure 11 This is an optical microscope (10×40x) image of the Dunaliella salina suspension after membrane rupture treatment in Comparative Example 6. Detailed Implementation

[0028] The following specific embodiments further illustrate the content of the present invention, but should not be construed as limiting the present invention.

[0029] Example 1

[0030] An extract of Dunaliella salina was prepared according to the following method: (1) Raw material preparation: Add deionized water and NaCl to Dunaliella salina to prepare a high-salt Dunaliella salina suspension with a mass volume concentration of 100 g / L. The mass volume fraction of NaCl in the high-salt Dunaliella salina suspension is 15% (W / V, that is, 100 mL of high-salt Dunaliella salina suspension contains 15 g of NaCl). (2) Construction of in-situ continuous desalination and emulsification dispersion system: Under stirring conditions of 50 r / min, deionized water was added dropwise to the high-salt algae suspension obtained in step (1) at a rate of 0.5% per minute to reduce the mass volume fraction of NaCl from 15% (W / V) to 5% (W / V, i.e., 5g NaCl in 100mL of high-salt algae suspension); at the same time, surfactant Tween 80, co-surfactant butylene glycol and medium-chain triglycerides in the oil phase were added sequentially, and each component was added dropwise within 5 min. The resulting reaction system was transferred to a high-pressure homogenizer and circulated 3 times under a pressure of 1500 bar to form a semi-transparent emulsion; the amount of surfactant Tween 80, co-surfactant butylene glycol and medium-chain triglycerides in the oil phase added accounted for 2%, 12% and 5% of the mass percentage of the reaction system, respectively. (3) Separation and purification: Centrifuge the emulsion obtained in step (2) at 10000 r / min for 5 min and collect the supernatant; filter the supernatant through 5 μm, 1.2 μm and 0.45 μm microporous membranes in sequence and collect the filtrate to obtain the Dunaliella salina extract.

[0031] Example 2

[0032] The other steps are the same as in Example 1, except that the mass volume fraction of NaCl in step (2) is gradually reduced from 15% to 8% (W / V, i.e., 8g NaCl is contained in 100mL of high-salt algae suspension).

[0033] Example 3

[0034] The other steps are the same as in Example 1, except that the mass volume fraction of NaCl in the high-salt algae suspension in step (1) is 13% (W / V, that is, 100mL of high-salt algae suspension contains 13g of NaCl), and the mass volume fraction of NaCl in step (2) is gradually reduced from 13% to 3% (W / V, that is, 100mL of high-salt algae suspension contains 3g of NaCl).

[0035] Example 4

[0036] The other steps are the same as in Example 1, except that the reaction system components in step (2) are different, that is, the specific substances of the added surfactant, co-surfactant and oil phase are different, namely, the surfactant PEG-40 hydrogenated castor oil, the co-surfactant 1,2-hexanediol and the oil phase jojoba oil.

[0037] Example 5

[0038] The other steps are the same as in Example 1, except that the reaction system composition ratio in step (2) is different, that is, the amount of surfactant Tween 80, co-surfactant butanediol and oil phase medium-chain triglycerides added are different, accounting for 1.5%, 18% and 6.5% of the mass percentage of the reaction system, respectively.

[0039] Comparative Example 1

[0040] This comparative example uses the traditional drying and pulverizing method to extract Dunaliella salina extract, specifically following the steps below: The algae of Dunaliella salina were dried, pulverized, and passed through an 80-mesh sieve to obtain Dunaliella salina powder. A 70% ethanol solution was added at a material-to-liquid ratio of 1g:20mL, and the mixture was refluxed twice for 1 hour each time. The extracts were combined, filtered, and the filtrate was collected to obtain Dunaliella salina extract.

[0041] Comparative Example 2

[0042] The other steps are the same as in Example 1, except that in step (2), deionized water is added quickly and all at once to the high-salt algae suspension, so that the mass volume fraction of NaCl in it drops directly from 15% to 5%.

[0043] Comparative Example 3

[0044] The other steps are the same as in Example 1, except that no desalination treatment is performed in step (2). That is, step (2) of this comparative example is as follows: (2) Under stirring conditions of 50 r / min, the surfactant Tween 80, the co-surfactant butanediol and the oil phase medium-chain triglyceride were added to the high-salt algae suspension obtained in step (1) in sequence. Each component was added dropwise within 5 min. The resulting reaction system was stirred for another 60 min. The resulting product was then separated and purified in the subsequent step (3). The amount of surfactant Tween 80, co-surfactant butanediol and the oil phase medium-chain triglyceride added accounted for 2%, 12% and 5% of the mass percentage of the reaction system, respectively.

[0045] Comparative Example 4

[0046] The other steps are the same as in Example 1, except that in step (2), the surfactant Tween 80 is not added, but only the co-surfactant butylene glycol and the medium-chain triglyceride in the oil phase are added.

[0047] Comparative Example 5

[0048] The other steps are the same as in Example 1, except that in step (2), no co-surfactant butanediol is added, and only the surfactant Tween 80 and medium-chain triglycerides in the oil phase are added.

[0049] Comparative Example 6

[0050] The other steps are the same as in Example 1, except that in step (2), medium-chain triglycerides in the oil phase are not added, and only the surfactant Tween 80 and the co-surfactant butylene glycol are added.

[0051] Test Example 1: Verification of β-carotene extraction efficiency

[0052] The β-carotene content of the Dunaliella salina extracts prepared in Examples 1-5 and Comparative Examples 1-6 was determined according to GB 1886.317-2021. The results are shown in Table 1.

[0053] Table 1 Comparison of β-carotene content

[0054] As can be seen from Table 1, the β-carotene content in the Dunaliella salina extracts prepared in Examples 1-5 of the present invention is 3.46-3.92 mg / mL, which is significantly higher than the β-carotene content in the Dunaliella salina extracts prepared in Comparative Examples 1-6.

[0055] The embodiments of the present invention employ an in-situ gradient desalination coupled emulsification dispersion extraction process, which can achieve efficient membrane rupture of Dunaliella salina under mild conditions, allowing intracellular β-carotene to be fully released and stably encapsulated by the emulsion system, effectively avoiding degradation of heat-sensitive components. Therefore, the resulting extract has a high content and high retention rate of active ingredients.

[0056] Comparative Example 1 used traditional drying, pulverizing, and high-temperature extraction methods, resulting in severe thermal degradation of β-carotene. Comparative Example 2 used a one-time rapid desalination method, leading to insufficient cell wall disruption of Dunaliella salina. Comparative Example 3 did not undergo desalination treatment, resulting in a low cell wall disruption rate of Dunaliella salina. Comparative Examples 4-6 lacked surfactants, co-surfactants, or oil phases, respectively, which prevented the formation of a stable emulsion system, reduced extraction and stabilization effects, and ultimately led to a significant decrease in β-carotene content.

[0057] In summary, this invention utilizes the osmotic pressure impact generated by gradient desalination to achieve in-situ cell wall disruption of Dunaliella salina, and simultaneously constructs an in-situ emulsification system during the desalination process. This method achieves a continuous in-situ integrated process of desalination, emulsification, cell wall disruption, and extraction, which can significantly improve the extraction efficiency and retention rate of β-carotene from Dunaliella salina. The resulting extract has a high content of active ingredients and is suitable as a functional raw material for sunscreen, antioxidant, and skin repair cosmetics.

[0058] Test Example 2: Determination of Film Breakage Rate

[0059] The cell perforation rate of Dunaliella salina was determined by trypan blue staining and microscopic counting.

[0060] Take 1 mL of the Dunaliella salina suspension after membrane rupture treatment in each example and comparative example (sampled when NaCl drops to the set mass volume fraction after deionized water is added in step (2) of Examples 1-5 and Comparative Examples 2, 4-6; sampled when Dunaliella salina powder is obtained in Comparative Example 1 and dissolved in deionized water to obtain Dunaliella salina suspension with a mass volume concentration of 100 g / L; sampled when high-salt Dunaliella salina suspension is obtained in step (1) of Comparative Example 3), add an equal volume of trypan blue staining solution with a mass volume fraction of 0.4% (W / V), mix well, stain at room temperature in the dark for 3 min, drop onto a hemocytometer, and calculate the percentage of damaged cells, i.e., membrane rupture rate, by the total number of cells in the field of view and the number of cells after blue staining.

[0061] Membrane perforation rate (%) = (Number of blue-stained cells / Total number of cells) × 100% Total cell count: The total number of Dunaliella salina cells counted under a microscope; Blue staining cell number: The number of cells stained with trypan blue.

[0062] Table 2 shows the cell perforation rate of Dunaliella salina in the extracts prepared in Examples 1-5 and Comparative Examples 1-6.

[0063] Table 2 Comparison of membrane breakage rate

[0064] Take 1 mL of the *Dunaliella salina* suspension after membrane rupture treatment from each example and comparative example (as above), dilute it 10-fold, and observe it using an optical microscope (10×40x). Take microscopic images of the cells treated in each example and the comparative example, as shown below. Figures 1-11 As shown.

[0065] The results showed that the film breakage rate of Examples 1-5 and Comparative Examples 4-6 of the present invention reached 86.3%-89.8%, indicating sufficient film breakage; due to process defects, the film breakage rate of Comparative Examples 1-3 was only 37.8%-44.3%, which was significantly lower than that of the Examples, proving that the gradient desalination in-situ emulsification process of the present invention has significant advantages.

[0066] Microscopic observation results show that the in-situ gradient desalination process employed in this invention can fully and uniformly rupture the Dunaliella salina cell membrane through gentle osmotic pressure impact, resulting in efficient release of intracellular active substances and a significant membrane rupture effect. In the Example Group and Comparative Examples 4-6, most Dunaliella salina cells were completely ruptured after in-situ gradient desalination treatment, with only a few intact cells remaining. Comparative Examples 1-3 cells largely maintained their intact cell structure, failing to achieve efficient membrane rupture and active substance release. Figures 1-11 The trend characteristics of the microscopic morphology are basically consistent with the film breakage rate data in Table 2, which fully demonstrates the superiority of the film breakage process of the present invention.

[0067] Test Example 3: Antioxidant Capacity Determination

[0068] The antioxidant capacity was tested using the DPPH free radical scavenging method. The Dunaliella salina extracts prepared in Examples 1-5 and Comparative Examples 1-6 were used to prepare sample test solutions with a mass concentration of 0.1 mg / mL using anhydrous ethanol as the solvent. Vitamin C solution (0.04 mg / mL) was used as a control sample. Measurements were taken on the day of preparation (day 0) and after 15 days of storage at room temperature in the dark (day 15). Anhydrous ethanol was used as a blank group, and the absorbance was measured at a wavelength of 517 nm. The scavenging rate was calculated using the following formula: DPPH free radical scavenging rate (%) = (A0 - A1) / A0 × 100% In the formula: A0 is the absorbance of the blank group; A1 is the absorbance of the sample group.

[0069] Table 3 Comparison of antioxidant capacity

[0070] The antioxidant test results are shown in Table 3. The Dunaliella salina extracts prepared in Examples 1-5 of this invention exhibited a DPPH free radical scavenging rate of 87.2%-92.4% on day 0, and maintained at 82.9%-88.3% after 15 days at room temperature, with an activity retention rate ≥95.1%, indicating strong antioxidant activity and high stability. This is because the in-situ emulsification system can form a stable encapsulation of antioxidant components such as β-carotene and polyphenols, preventing oxidative degradation; and the low-temperature, normal-pressure process throughout maximizes the preservation of natural activity. In contrast, the Dunaliella salina extracts prepared in Comparative Examples 1-6, due to the use of traditional high-temperature extraction, rapid desalination, no desalination, or the absence of microemulsion components, could not form a stable encapsulation system, resulting in significantly lower antioxidant activity. Furthermore, the activity decreased sharply after 15 days, with a retention rate of only 40.3%-87.8%. The control group vitamin C solution (0.04 mg / mL) showed excellent initial antioxidant activity, with a DPPH free radical scavenging rate of 90.5±1.0%. However, its anti-aging and antioxidant stability was poor. After being placed at room temperature for 15 days, the scavenging rate dropped to 71.2±1.5%, and the activity retention rate was only 78.7%, which was much lower than that of the samples in the embodiments of this invention. This further confirms that the in-situ desalination coupled emulsification dispersion extraction technology can significantly improve the antioxidant efficacy and long-term stability of Dunaliella salina active ingredients.

[0071] Test Example 4: Determination of UV Radiation Resistance

[0072] The Dunaliella salina extracts obtained in Examples 1-5 and Comparative Examples 1-6 were used to prepare sample test solutions with a mass concentration of 0.1 mg / mL using 50% ethanol solution as the solvent. Rutin solution (0.02 mg / mL) was used as the control sample solution. Using 50% ethanol solution as a blank control, the average absorbance of each group of sample solutions in the UVB (280-320 nm) and UVA (320-400 nm) bands was measured using UV-Vis spectrophotometry to evaluate the UV absorption capacity.

[0073] Table 4 Comparison of UV radiation resistance

[0074] The UV absorption test results are shown in Table 4: Examples 1-5 of the present invention have absorbance of 0.77-0.86 in the UVB region and 0.64-0.72 in the UVA region, showing strong UV absorption across the entire UV spectrum and good natural sun protection effect. This is because fat-soluble sun protection ingredients such as β-carotene are fully extracted and uniformly dispersed in the emulsion system, which improves UV absorption efficiency and photostability.

[0075] The control group rutin solution (0.02 mg / mL), as a classic natural UV protection substance, had average UVB and UVA absorbances of 0.75±0.04 and 0.62±0.03, respectively, demonstrating good UV absorption capacity. However, the comparison shows that the UVA and UVB absorbances of each embodiment of the present invention are generally better than those of the rutin control sample, proving that the anti-UV radiation effect of the Dunaliella salina extract prepared by the present invention is better than that of conventional natural flavonoid sunscreens.

[0076] The Dunaliella salina extracts prepared in Comparative Examples 1-6 had UV absorbance of only 0.23-0.59 due to insufficient cell wall disruption, degradation of active ingredients, and lack of emulsification system components, resulting in significantly lower sun protection capabilities compared to the Dunaliella salina extracts obtained in the embodiments of this invention.

[0077] In summary, this invention utilizes an integrated, mild extraction process that combines in-situ gradient desalination with emulsification and dispersion to significantly improve the extraction efficiency, stability, and sun protection efficacy of Dunaliella salina active ingredients. The resulting extract is suitable as a highly effective functional ingredient for sun protection and antioxidant cosmetics.

[0078] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing Dunaliella salina extract, characterized in that... The following steps are included: (1) Raw material preparation: Add deionized water and NaCl to Dunaliella salina to prepare a high-salt Dunaliella salina suspension with a mass-volume concentration of 100 g / L, wherein the mass-volume fraction of NaCl in the high-salt Dunaliella salina suspension is 10%~20%; (2) Construction of in-situ continuous desalination and emulsification dispersion system: Under stirring conditions of 50 r / min, deionized water was added dropwise to the high-salt algae suspension obtained in step (1) at a rate of 30 drops per minute, so that the mass volume fraction of NaCl in it was steadily reduced from 10%~20% to 3%~8%; at the same time, surfactant, co-surfactant and oil phase were added in sequence, and each component was added dropwise within 5 min. The resulting reaction system was transferred to a high-pressure homogenizer and circulated 3~5 times under a pressure of 1200~1500 bar to form a semi-transparent emulsion; the amount of surfactant, co-surfactant and oil phase added accounted for 1%~3%, 5%~25% and 3%~8% of the mass percentage of the reaction system, respectively. (3) Separation and purification: Centrifuge the emulsion obtained in step (2) at 8000~10000 r / min for 5~10 min and collect the supernatant; filter the supernatant through 5 μm, 1.2 μm and 0.45 μm microporous membranes in sequence and collect the filtrate to obtain the Dunaliella salina extract.

2. The method for preparing Dunaliella salina extract according to claim 1, characterized in that: The surfactant in step (2) is one or more of Tween 20, Tween 60, Tween 80, PEG-20 hydrogenated castor oil, PEG-40 hydrogenated castor oil, and PEG-60 hydrogenated castor oil; the co-surfactant is one or more of ethanol, 1,2-propanol, 1,3-propanediol, 1,3-butanediol, and 1,2-hexanediol; and the oil phase is one or more of medium-chain triglycerides, isopropyl myristate, sunflower oil, corn oil, and jojoba oil.

3. A Dunaliella salina extract prepared by the preparation method according to claim 1 or 2.

4. The application of the Dunaliella salina extract according to claim 3 in the preparation of cosmetics with sun protection and antioxidant effects.

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