High-antioxidant extracellular polymeric substance derived from porphyridium viride and preparation method of extracellular polymeric substance

Abstract

The invention discloses a high-antioxidant extracellular polymeric substance derived from porphyridium virens, the extracellular polymeric substance is derived from the porphyridium virens, and the preservation number of the porphyridium virens is CCTCC (China Center for Type Culture Collection) NO: M 20241906. The invention further discloses a preparation method of the high-antioxidant extracellular polymeric substance derived from the porphyridium virens. The invention also discloses the extracellular polymeric substance and application thereof. The novel Porphyridium viride sp.Fan-3 is obtained, and the extracellular polymeric substance produced by the Porphyridium viride sp.Fan-3 is specific in composition, has a remarkable anti-oxidation effect, can be used as an oxidizing agent in food, cosmetics and medicines, and has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of production and preparation of extracellular polymers of microalgae, and in particular relates to a highly antioxidant extracellular polymer derived from green Porphyridium and a preparation method thereof. Background Art

[0002] Microalgae, a class of single-celled photosynthetic organisms, grow rapidly, are widely distributed, and are highly adaptable, surviving in a variety of extreme environments, including cold, heat, dryness, and acidity. Compared to larger algae like kelp, laver, and gracilaria, microalgae offer unique advantages, including high photosynthetic efficiency, ease of cultivation, abundant biomass, and potential for genetic engineering. Microalgae's high biomass yields are underpinned by their efficient carbon dioxide fixation. Microalgae biomass is rich and diverse, comprising carbohydrates, proteins, peptides, and lipids, which form the metabolic network that sustains normal physiological and biochemical functions.

[0003] Extracellular polymeric substances (EPMS) are a class of macromolecular polymers that are processed and secreted outside algal cells via the endoplasmic reticulum. Research has focused on the genus Porphyridium (Porphyridium sp.) of the red algae phylum, with some studies also examining green algae and cyanobacteria. The polysaccharide chains of Porphyridium sp. EPMS are composed of glucose, xylose, galactose, and other monosaccharides, attached to 66 kDa glycoproteins, sulfate substituents, and uronic acid. Furthermore, extracellular proteins and lipids form a three-dimensional hydrated gel-like network surrounding the cell membrane. EPMS have been found in Porphyridium sordidum, Porphyridium purpureum, Porphyridium cruentum, and Porphyridium aerugineum, with yields increasing with culture time, reaching 4-5 g / L.

[0004] From a compositional perspective, EPMS is a complex composed of macromolecular polysaccharide chains, proteoglycans, proteins, enzymes, nucleic acids, lipids, and more. These diverse substances contribute to the complex EPMS structure, with polysaccharides, a current research hotspot, accounting for over 40% of the total. These polysaccharides possess anti-inflammatory, anti-tumor, anti-radiation, and antioxidant properties, and can be used as cosmetic ingredients in skin care, offering anti-wrinkle, moisturizing, and hydration benefits. Proteins, such as glycoproteins, also contribute to the formation of the EPMS matrix network, maintaining its stability. The presence of extracellular enzymes can contribute to EPMS remodeling and degrading older EPMS components, providing energy and carbon sources for cells while also opening up new EPMS synthesis.

[0005] Microalgae EPMS can be used in the development of cosmetic raw materials, which can brighten the skin and moisturize and lock in moisture. The interaction between EPMS and skin cells can promote the biosynthesis of natural moisturizing factors by upregulating the expression of filaggrin, thereby enhancing the moisturizing ability of the stratum corneum. Filaggrin can also synergize with involucrin and loricrin to form a cell envelope, further enhancing the function and moisturizing ability of the epidermal barrier. EPMS can also protect algal cells from UV-B radiation and can be developed into cosmetic raw materials with photoprotection, antioxidant and regenerative properties. In addition, EPMS also has the function of regulating the viscosity of cosmetics and regulating skin feel. The Israeli company Frutarom has achieved commercial cultivation of Porphyridium cruentum EPMS in plastic hanging bags for the development of cosmetic raw materials, such as the product Alguard TM PF. Swiss RAHN AG has developed P.cruentum extract into a cosmetic formula for smoothing wrinkles. Similar products include Givaudan's Hydrintense TM .

[0006] In recent years, extensive research has focused on Porphyridium cruentum EPMS, focusing on its excellent free radical scavenging capabilities, ability to inhibit tumor cell proliferation, regulation of inflammatory cytokine expression, and its excellent moisture retention and adhesion properties for adsorbing harmful molecules. However, numerous challenges exist, including slow EPMS accumulation, complex post-processing, and high energy consumption. Furthermore, the prepared EPMS exhibits low solubility after resuspension and high losses during the alcohol precipitation process, significantly limiting the development and application of end-use products. Summary of the Invention

[0007] The inventors of this application isolated and induced a green Porphyridium sp. Fan-3 from seawater. Research revealed that the composition of its extracellular polymeric substances (ECPs) differed significantly from that of similar Porphyridium species, primarily consisting of polysaccharides and uronic acid, with mannose comprising a significant proportion of the polysaccharide fraction. Further research revealed that these ECPs possess significant antioxidant activity and could be used as oxidants in food, cosmetics, and pharmaceuticals.

[0008] Therefore, the first aspect of the present invention provides a highly antioxidant extracellular polymer derived from green Porphyridium, wherein the extracellular polymer is derived from green Porphyridium sp. Fan-3, and the preservation number of green Porphyridium sp. Fan-3 is CCTCC NO: M 20241906.

[0009] According to the present invention, the main components of the extracellular polymers are polysaccharides and uronic acid.

[0010] Furthermore, the extracellular polymers are composed of polysaccharide chains of sugars such as mannose, glucose, galactose, and xylose.

[0011] The second aspect of the present invention provides a method for preparing the highly antioxidant extracellular polymeric substance, which is obtained by culturing green Porphyridium sp. Fan-3, the preservation number of which is CCTCC NO: M 20241906.

[0012] According to a preferred embodiment of the present invention, the composition of the KOCK medium used for culturing the green Porphyridium sp. Fan-3 is as follows:

[0013] KNO3 0.75g / L, KH2PO4 0.025g / L, MgSO4·7H2O 0.2g / L, C6H5FeO7 0.0025g / L, ReefCrystals sea salt 7.5g / L, pH=7.35.

[0014] Preferably, the light intensity for culturing the green Porphyridium sp. Fan-3 is 90 to 110 μmol / m 2 / s, the temperature is 25±1°C. More preferably, the light intensity of the culture is 100 μmol / m 2 / s.

[0015] The third aspect of the present invention provides the use of the highly antioxidant extracellular polymer as an antioxidant.

[0016] According to the present invention, the extracellular polymers can be used as oxidants in food, cosmetics and medicine.

[0017] A fourth aspect of the present invention provides a green Porphyridium sp. Fan-3, whose accession number is CCTCC NO: M 20241906.

[0018] The present invention obtains a new green purple crucian carp Porphyridium sp. Fan-3, which produces extracellular polymers with a composition significantly different from that produced by similar purple crucian carp, has a significant antioxidant effect, can be used as an oxidant in food, cosmetics and medicine, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a diagram showing the results of separation and purification of Porphyridium sp. Fan-3 on KOCK solid culture medium.

[0020] Figure 2 This is an optical microscope image of Porphyridium sp. Fan-3.

[0021] Figure 3 This is a transmission electron micrograph of a cell section of Porphyridium sp. Fan-3.

[0022] Figure 4 Shown are the growth conditions of Porphyridium sp. Fan-3 and other Porphyridium species in KOCK.

[0023] Figure 5 The cell density of Porphyridium sp. Fan-3 and other Porphyridium species at the end of culture is shown.

[0024] Figure 6 The dry weight of algal mud of Porphyridium sp. Fan-3 and other Porphyridium species at the end of cultivation is shown.

[0025] Figure 7 The results show the changes in the accumulation of EPMS secretion by Porphyridium sp. Fan-3 and other Porphyridium species in KOCK.

[0026] Figure 8 Shows a real picture of EPMS powder of Porphyridium sp. Fan-3.

[0027] Figure 9 Shown is a scanning electron micrograph of EPMS powder of Porphyridium sp. Fan-3.

[0028] Figure 10 The composition of EPMS secreted by each algal species is shown.

[0029] Figure 11 This shows the ability of vitamin C to scavenge OH free radicals.

[0030] Figure 12 The results showed that EPMS secreted by Porphyridium sp. Fan-3 and other Porphyridium species have the ability to scavenge ·OH free radicals.

[0031] Preservation Matters

[0032] The green purple algae Porphyridium sp. Fan-3 obtained in the present invention was submitted to the China Center for Type Culture Collection at Wuhan University, Wuhan, China for preservation on September 4, 2024, with the preservation number: CCTCC NO: M 20241906. DETAILED DESCRIPTION

[0033] The technical solutions of the present invention will be described in detail below with reference to specific embodiments. Obviously, the embodiments only represent some applications of the present invention, not all implementation methods.

[0034] Description of the detection method:

[0035] 1. Determination of total sugar concentration:

[0036] The total sugar content of the prepared EPMS powder was determined using the phenol-sulfuric acid method with glucose as the standard, and the purity was calculated:

[0037] Purity = (total sugar mass / EPMS mass) × 100%.

[0038] 2. EPMS composition:

[0039] The EPMS components were analyzed by HPLC. The EPMS powder was hydrolyzed with trifluoroacetic acid and then derivatized with 1-phenyl-3-methyl-5-pyrazolone to make it carry a group that can absorb ultraviolet light. 18 The chromatographic columns were separated, the retention times were compared with those of the standards, and the quantification was performed using the internal standard method.

[0040] 3. OH free radical scavenging experiment:

[0041] Based on the Fenton reaction, H2O2 and Fe 2+ The reaction generates ·OH, which is developed using Griess reagent. The color depth is proportional to the ·OH concentration. Vitamin C is used as a positive control. For specific methods, refer to the hydroxyl radical assay kit from the Nanjing Jiancheng Bioengineering Institute.

[0042] Example 1: Isolation, purification and morphological observation of Porphyridium sp. Fan-3

[0043] The green purple algae Porphyridium sp. Fan-3 of the present invention was isolated from a water sample in the southeast coast and obtained through laboratory mutagenesis. After multiple passages and stabilization, a sterile single algae colony was isolated and obtained. Figure 1 A photograph of a single algal colony is shown. By amplifying the rbcL gene sequence and performing a Blast (Nucleotide to Nucleotide) comparison search on NCBI, it was found that the species with the highest homology are Porphyridium purpureum, Porphyridium sordidum, and Porphyridium aerugineum. These algae species all belong to the genus Porphyridium in the Rhodophyta. Therefore, the algae species in this invention are named Porphyridium sp.

[0044] The isolated single algae colony was diluted and placed under an optical microscope to observe its cell morphology and size. Figure 2 As shown. Figure 2 Results show that Porphyridium sp. Fan-3 is bright green, round, with irregular edges and a bumpy surface. Its diameter is 5-7 μm, similar in size to P. purpureum and P. aerugineum species. Its cells are tightly connected and clustered together. This is likely due to the mutual attraction between cells. It lacks flagella or other motile structures and may grow attached to rock surfaces or floating in water.

[0045] In addition, the algae mud was collected and fixed with glutaraldehyde overnight, treated with osmium acid, dehydrated with ethanol, embedded and sliced, and stained to observe the internal morphology of the cells by TEM. Figure 3 shown.

[0046] Depend on Figure 3 The results show that there is a layer of flocculent material around the cell wall of Porphyridium sp. Fan-3, which is the EPMS described in the present invention. It can gradually accumulate in the culture medium as the culture time increases; inside the cell, the cytoplasm seems to be divided into two, which may be in the division stage.

[0047] Example 2: Cultivation of Porphyridium sp. Fan-3

[0048] The KOCK medium of this example has been modified and contains the following components: 0.75 g / L KNO3, 0.025 g / L KH2PO4, 0.2 g / L MgSO4·7H2O, 0.0025 g / L C6H5FeO7, and 7.5 g / L Reef Crystals sea salt, dissolved in deionized water, adjusted to pH 7.35, filtered through a 0.22 μm filter membrane, and sterilized at 121°C for 20 min before use.

[0049] Seed solution culture: Porphyridium sp. Fan-3 was inoculated into a modified KOCK medium and cultured under autotrophic conditions to the logarithmic growth phase (about 6 days) to obtain Fan-3 seed solution.

[0050] Shaker experiment culture: centrifuge the seed solution at 5000rpm for 5min, harvest the algae mud, wash the algae mud with fresh KOCK medium to remove the old medium, and then inoculate it into fresh KOCK medium. In order to make the algae cells reach the logarithmic growth phase faster, the initial OD 750 =0.50±0.01. After 20 days of constant temperature culture on a shaker, the culture supernatant was harvested and used to prepare EPMS. During this period, the algal cell growth was monitored.

[0051] The light intensity of the culture is 90-110 μmol / m 2 / s, preferably 100 μmol / m 2 / s.

[0052] The culture temperature is 25±1°C.

[0053] Example 3. Growth of Porphyridium sp. Fan-3 and EPMS Accumulation

[0054] Centrifuge the seed solution in the logarithmic growth phase, remove the old culture medium, and inoculate it into a shake flask for culture experiment. 2 / s light and a constant temperature of 25℃, and three red purple algae Porphyridiumaerugineum, Porphyridium purpureum, and Porphyridium cruentum were used as controls.

[0055] Figure 4 、 Figure 5 、 Figure 6 Shows the growth of Porphyridium sp. Fan-3 in KOCK. Figure 4 The results showed that Fan-3 grew similarly to P.aerugineum, P.purpureum, and P.cruentum in the modified KOCK medium. After 20 days of culture, the initial OD 750 =0.49, rising to OD 750 =2.92. Figure 5 and Figure 6 The results showed that the dry weight could reach 3.0 g / L after the culture, and the cell number was 2.74×10 7 cells / mL, indicating that KOCK medium provides rich nutrients for the growth of Fan-3.

[0056] Figure 7 The results reflect the changes in the accumulation of EPMS secreted into the culture medium by each species of Porphyridium during the growth stage. It can be seen that EPMS accumulation is less in the early stage of culture. This is because the algal cells direct most of their energy to growth and division during this period. As the density of the algal cells increases, the accumulation of EPMS increases significantly after entering the stable period. The sources include: cell wall dissolution and cell autolysis leading to the release of cytoplasmic contents such as starch granules.

[0057] Example 4: EPMS powder morphology of Porphyridium sp. Fan-3

[0058] EPMS preparation method: After the culture, the algal liquid was centrifuged at 12,000 rpm for 10 minutes, and the supernatant was harvested. The supernatant was dialyzed for 36 hours at 4°C using a 500 Da dialysis bag to remove salts. The conductivity after dialysis decreased from 10.82 mS / cm before dialysis to 0.11 mS / cm, demonstrating a good dialysis effect. Without ethanol precipitation or other organic phase intervention, the dialyzed liquid was directly pre-cooled at -80°C and freeze-dried in a vacuum for 48 hours to obtain EPMS powder, which was used in subsequent experiments.

[0059] The traditional method for preparing EPMS is to use organic phases such as ethanol to reduce the solubility of EPMS in water and then obtain a precipitate. However, in this experiment, ethanol was unable to effectively precipitate EPMS, which may be due to the different types and characteristics of EPMS.

[0060] Figure 8 This is a real picture of the EPMS powder of Porphyridium sp. Fan-3. It can be seen that the EPMS powder is light yellow, soft, matte, odorless, easy to clump, and can disperse when pressure is applied. In the experiment, it was found that it has high solubility, which is conducive to subsequent research.

[0061] Scanning electron microscopy was used to reveal the microstructure of EPMS. Figure 9 As shown in the figure, the surface of the EPMS powder of Porphyridium sp. Fan-3 is rough and uneven, showing an amorphous structure. There is a small amount of flocculent material, which may be caused by the natural aggregation of EPMS during the drying process. The irregular flocculent and agglomerated materials are interwoven to form a loose porous network structure, showing a high specific surface area, which is conducive to the formation of a natural barrier and biologically active applications.

[0062] Example 5: EPMS composition of Porphyridium sp. Fan-3

[0063] To further analyze the composition of the EPMS, the present embodiment used the phenol-sulfuric acid method and the m-hydroxybiphenyl method to analyze the composition of the EPMS in Porphyridium sp. Fan-3 and three red-type purple algae, Porphyridium aerugineum, Porphyridium purpureum, and Porphyridium cruentum. The HPLC-PMP pre-column derivatization method was used to detect the monosaccharide composition with various monosaccharide standards as controls. The results are shown in FIG. Figure 10 and as shown in Table 1.

[0064] Table 1: Monosaccharide composition and proportion of total sugars in EPMS secreted by various algae species (wt%)

[0065] Monosaccharide composition glucose(%) Galactose (%) Xylose (%) Mannose (%) Porphyridium sp.Fan-3 20.59±1.19 7.22±0.65 9.62±1.24 20.78±1.36 Porphyridium aerugineum 15.04±1.60 19.42±0.96 22.34±0.97 / Porphyridium purpureum 16.25±0.43 33.76±0.48 29.99±1.42 / Porphyridium cruentum 9.43±0.72 32.44±2.19 21.83±2.33 /

[0066] Figure 10 The composition of EPMS of Porphyridium sp. Fan-3, Porphyridium aerugineum, Porphyridium purpureum, and Porphyridium cruentum is shown, among which polysaccharides are the main components. Polysaccharides account for 29.79% of the EMPS of Porphyridium sp. Fan-3, followed by 19.67% of uronic acid. In addition, the present invention also detected 11.41% of ash and trace amounts (0.34%) of nucleic acids. Similar to other algae species, polysaccharides are the main components of EPMS in the EMPS of Porphyridium sp. Fan-3, but in particular, uronic acid accounts for a larger proportion. As a polyhydroxy acid containing a carboxyl group, uronic acid can chelate with metal ions, such as Fe 2+ 、Cu 2+ , inhibiting the Fenton reaction, reducing the production of free radicals, and reducing oxidative damage to cells. Uric acid can also serve as a substituent or branching group in polysaccharide chains or glycoproteins, participating in their structural composition and enhancing the overall antioxidant properties of polysaccharides.

[0067] Table 1 shows the proportion of monosaccharides to total sugars in the EPMS powder of Porphyridium sp. Fan-3. The polysaccharide chains are composed of sugars such as mannose, glucose, galactose, and xylose. Unlike red-line Porphyridium sp. Fan-3, mannose accounts for a larger proportion of total sugars in the EPMS.

[0068] Because EPMS has a complex composition, including lipids, inorganic salts, etc.; the polysaccharide chains are intertwined, and their molecular weight affects the acid hydrolysis effect. Existing analytical detection methods are difficult to quickly and accurately reveal all its components, but the main components such as carbohydrates and uronic acid are accurately determined in the present invention.

[0069] Example 6: Antioxidant Capacity of Porphyridium sp. Fan-3 EPMS Powder

[0070] OH free radicals are a highly active species of reactive oxygen species in biological systems. Due to their strong chemical activity, they can react with various biological macromolecules, causing oxidative damage to important molecules within cells, such as DNA, proteins, and lipids. Scavenging free radicals can prevent peroxidation of cell membrane lipids and maintain normal cell function and morphology.

[0071] In this example, the scavenging ability of EPMS of Porphyridium sp. Fan-3 on ·OH free radicals was investigated, while Porphyridium aerugineum, Porphyridium purpureum, Porphyridium cruentum and vitamin C were used as controls.

[0072] Figure 11-12 The results of ·OH radical scavenging by vitamin C and EPMS of four microalgae species (Porphyridium sp. Fan-3, Porphyridium aerugineum, Porphyridium purpureum, and Porphyridium cruentum) are shown. Table 2 shows the results of ·OH radical scavenging by EPMS of Porphyridium sp. Fan-3 and eight common microbial species.

[0073] Table 2: Antioxidant activity of EPMS from common microbial species

[0074] Species name Latin name OH radical scavenging ability (IC50 / EC50) References Porphyridium Porphyridium sp.Fan-3 0.1644 mg / mL The present invention Porphyridium P.purpureum FACHB 806 0.5±0.0mg / mL 1 Porphyridium P.cruentum CCALA 415 0.59±0.03mg / mL 2 Botrytis cinerea Botryococcus braunii SCS-1905 1.67±0.06mg / mL 3 Chlorella Chlorella pyrenoidosa FACHB-9 0.75 mg / mL 4 Scenedesmus Scenedesmus sp. 0.38 mg / mL 4 Leuconostoc Leuconostoc mesenteroides S81 1.7 mg / mL 5 Streptococcus thermophilus Streptococcus thermophilus CS6 2.0 mg / mL 6 Fomitopsis pinicola Fomitopsis pinicola >2.0 mg / mL 7

[0075] Depend on Figure 11-12 As shown in Table 2, the half-maximal effect concentration (EC 50 ) is 0.1017 mg / mL, the EC of EPMS of Porphyridium sp.Fan-3 50 is 0.1644 mg / mL, and the EC 50 The values ​​were similar; moreover, with the increase of the EPMS concentration of Porphyridium sp. Fan-3, the scavenging efficiency increased rapidly, and at 1 mg / mL, the maximum scavenging efficiency was 79.01%; however, after further increasing the sample concentration, the antioxidant effect gradually tended to saturation, which may be because the active ingredients in EPMS have reached their maximum efficacy.

[0076] Compared with the P.aerugineum, P.purpureum, and P.cruentum algae species involved in the present invention, Porphyridium sp.Fan-3 EPMS has the best antioxidant effect. At a concentration of 2 mg / mL, the scavenging effect is 3.66 times, 1.89 times, and 2.12 times that of the above algae species, respectively. Compared with the reported literature in Table 2, the scavenging ability of EPMS of other microalgae on OH free radicals, such as C.pyrenoidosa FACHB-9IC 50 =0.75 mg / mL, B. braunii SCS-1905IC 50=1.67mg / mL, Scenedesmus sp.IC 50 =0.38mg / mL, Porphyridium purpureum IC 50 =0.5 mg / mL, the EPMS of Porphyridium sp. Fan-3 has a significant advantage.

[0077] EPMS, secreted by Porphyridium sp. Fan-3, exhibits significant antioxidant properties and holds broad application prospects as a promising new antioxidant. Furthermore, as a natural product, EPMS possesses higher biocompatibility than synthetic antioxidants, offering unique advantages in applications such as food, cosmetics, and pharmaceuticals.

[0078] References:

[0079] 1. Li, Q. et al. Effect of salinity on the biochemical characteristics and antioxidant activity of exopolysaccharide of Porphyridium purpureum FACHB806. Front. Mar. Sci. 9, (2023).

[0080] 2. Wang, W.-N. et al. Comparison on characterization and antioxidant activity of exopolysaccharides from two Porphyridium strains. J. Appl. Phycol. 33, 2983–2994 (2021).

[0081] 3. Wang, W.-N. et al. Exopolysaccharides from the Energy Microalga StrainBotryococcus braunii: Purification, Characterization, and AntioxidantActivity. Foods 11,110 (2022).

[0082] 4.Zhang,J.,Liu,L.,Ren,Y.&Chen,F.Characterization ofexopolysaccharides produced by microalgae with antitumor activity on humancolon cancer cells.International Journal of Biological Macromolecules 128,761–767(2019).

[0083] 5.Taylan,O.,Yilmaz,M.T.&Dertli,E.Partial characterization of a levantype exopolysaccharide(EPS)produced by Leuconostoc mesenteroides showingimmunostimulatory and antioxidant activities.International Journal ofBiological Macromolecules 136,436–444(2019).

[0084] 6.Zhou,Y.,Cui,Y.,Suo,C.,Wang,Q.&Qu,X.Structure,physicochemicalcharacterization,and antioxidant activity of the highly arabinose-branchedexopolysaccharide EPS-M2 from Streptococcus thermophilus CS6.InternationalJournal of Biological Macromolecules 192,716–727(2021).

[0085] 7.Hao,L.,Sheng,Z.,Lu,J.,Tao,R.&Jia,S.Characterization and antioxidantactivities of extracellular and intracellular polysaccharides from Fomitopsispinicola.Carbohydrate Polymers141,54–59(2016).

Claims

1. A highly antioxidant extracellular polymer derived from green Porphyridium, characterized in that: The extracellular polymer is derived from green Porphyridium sp. Fan-3, and the preservation number of the green Porphyridium sp. Fan-3 is CCTCC NO: M 20241906.

2. The highly antioxidant extracellular polymer according to claim 1, characterized in that The main components of the extracellular polymers are polysaccharides and uronic acid.

3. The highly antioxidant extracellular polymer according to claim 1 or 2, characterized in that: The extracellular polymer is composed of polysaccharide chains of sugars such as mannose, glucose, galactose, and xylose.

4. The method for preparing highly antioxidant extracellular polymers according to claim 1, characterized in that: The green Porphyridium sp. Fan-3 is obtained by culturing the green Porphyridium sp. Fan-3, and the accession number of the green Porphyridium sp. Fan-3 is CCTCC NO: M 20241906.

5. The preparation method according to claim 4, characterized in that: The composition of the KOCK medium used for culturing the green purple algae Porphyridium sp. Fan-3 is as follows: KNO3 0.75g / L, KH2PO4 0.025g / L, MgSO4·7H2O 0.2g / L, C6H5FeO7 0.0025g / L, ReefCrystals sea salt 7.5g / L, pH=7.

35.

6. The preparation method according to claim 5, characterized in that: The light intensity of the green purple algae Porphyridium sp. Fan-3 culture is 90-110 μmol / m 2 / s, temperature is 25±1℃.

7. The preparation method according to claim 6, characterized in that: The light intensity of the culture was 100 μmol / m 2 / s.

8. The use of the highly antioxidant extracellular polymer according to claim 1, characterized in that: Acts as an antioxidant.

9. The use according to claim 8, characterized in that: Used as an oxidant in food, cosmetics and medicine.

10. A green Porphyridium sp. Fan-3, characterized in that: Its accession number is CCTCCNO:M20241906.

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