A marine red algae polysaccharide extract and its use

Abstract

The application discloses a marine red alga polysaccharide extract and application thereof, and belongs to the technical field of marine organisms and medicines. Gigartina radula The polysaccharide extract is extracted from marine red algae, and the main component is natural galactosamine sulfate, contains galactose and glucose, has a sulfate content of 20-40%, a 3,6-endo ether galactose content of 20-50%, and a viscosity of 80-400 mPa s. The polysaccharide extract contains kappa-carrageenan structural units, iota-carrageenan structural units, mu-carrageenan structural units, nu-carrageenan structural units and lambda-carrageenan structural units, and the proportion of the lambda-carrageenan structural units is 10-50%. The marine red alga polysaccharide extract can be applied to the preparation of medicines or functional skin care products for preventing and / or treating inflammatory and immune-related skin diseases such as atopic dermatitis AD.

Description

Technical Field

[0001] This invention relates to the field of marine biomedicine technology, specifically to a marine red algae polysaccharide extract and its applications. Background Technology

[0002] Atopic dermatitis (AD) is a common chronic, relapsing, inflammatory skin disease characterized by intense itching, dry skin, eczematous lesions, and impaired skin barrier function. In the pathogenesis of AD, various immune cells participate in the initiation, maintenance, and chronicity of skin inflammation through a complex network of interactions. The activation of inflammatory cells and the generation of inflammatory molecules are closely related to the occurrence of AD. Oxidative stress is a core component of the pathogenesis of atopic dermatitis, forming a vicious cycle with skin barrier dysfunction and immune inflammatory responses. Abnormally elevated levels of reactive oxygen species (ROS) can directly damage keratinocytes, disrupt epidermal integrity, and induce autophagy and apoptosis by activating MAPK and inhibiting mTOR pathways, leading to epidermal homeostasis imbalance. Simultaneously, the characteristic Th2 inflammatory environment of AD (such as elevated levels of IL-4 and IL-13) promotes ROS generation; and ROS itself can upregulate the expression of pro-inflammatory cytokines and promote lipid peroxidation, thereby continuously driving disease progression.

[0003] Currently, the clinical treatment of Alzheimer's disease (AD) mainly adopts a stepwise management strategy, including basic skin care, topical medications, and systemic therapy. Topical medications are the first-line treatment for AD, primarily including corticosteroids (TCS) and calcineurin inhibitors (TCIs). Although TCSs have significant anti-inflammatory effects, long-term or large-area use may cause local adverse reactions such as skin atrophy, telangiectasia, and pigmentation changes, and there is a risk of systemic absorption side effects. While TCIs do not have hormone-related side effects, there may be potential long-term safety concerns, and their efficacy is limited in some moderate to severe patients. Therefore, developing a novel therapeutic agent that is effective, safe, suitable for long-term use, and naturally derived to meet unmet clinical needs is of significant practical importance. Summary of the Invention

[0004] The purpose of this invention is to provide a marine red algae polysaccharide extract and its applications to overcome the shortcomings of the prior art.

[0005] This extract is derived from carrageenan-based red algae. Gigartina radula This is a novel polysaccharide with unique activity; the present invention also provides its preparation method, thereby laying a technical foundation and providing experimental evidence for the specific application of this extract.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A polysaccharide extract from marine red algae, derived from marine red algae. Gigartina radula .

[0007] Furthermore, the main component of the marine red algae polysaccharide extract is natural galactomannan, comprising galactose (90-100%) and glucose (0-10%); the sulfate content is 20-40%, the 3,6-lactone galactose content is 20-50%, and the viscosity is 80-400 mPa·s.

[0008] Furthermore, the marine red algae polysaccharide extract mainly consists of highly sulfated carrageenan-type galactan, comprising κ-carrageenan structural units, ι-carrageenan structural units, μ-carrageenan structural units, ν-carrageenan structural units, and λ-carrageenan structural units. The λ-carrageenan structural units account for 10-50% of the total.

[0009] The marine red algae polysaccharide extract was obtained by extraction with purified water and precipitation with ethanol.

[0010] The application of the marine red algae polysaccharide extract is characterized by its use in the preparation of products for the prevention, relief and / or treatment of atopic dermatitis or immune-related skin diseases.

[0011] The application of the marine red algae polysaccharide extract is characterized by its application in anti-inflammatory and antioxidant products.

[0012] The application of the marine red algae polysaccharide extract is characterized by its use in the preparation of cosmetics or skin care products.

[0013] The application of the marine red algae polysaccharide extract is in the context of pharmaceutical compositions comprising the marine red algae polysaccharide extract and pharmaceutically acceptable carriers or excipients. The pharmaceutical compositions may be formulated into dosage forms suitable for topical administration, including but not limited to ointments, creams, gels, lotions, sprays, or patches.

[0014] The application of the marine red algae polysaccharide extract is characterized by its use in cosmetic or skincare compositions comprising the marine red algae polysaccharide extract and a cosmetically or skincare-acceptable carrier or excipient. The composition may be formulated as a serum, lotion, cream, mask, or body care product, etc.

[0015] The application is based on the following proven bioactivities of the marine red algae polysaccharide extract: 1. Anti-inflammatory effect: In vitro, it can significantly inhibit the production of nitric oxide (NO) and inflammatory factors (such as TNF-α and IL-6) by lipopolysaccharide (LPS)-induced macrophages (Raw 264.7).

[0016] 2. Antioxidant effect: It can significantly inhibit the release of ROS from macrophages in vitro.

[0017] 3. Improvement of AD animal model symptoms: In a 2,4-dinitrochlorobenzene (DNCB)-induced mouse AD model, topical application significantly reduced dermatitis severity scores, decreased skin and ear thickness, and reduced epidermal proliferation and inflammatory cell infiltration.

[0018] This invention relates to a marine red algae polysaccharide extract, whose main component's precise chemical structure has not been reported in the prior art, representing a novel sulfated galactan discovered and characterized for the first time. Known natural carrageenan is mainly composed of κ-type, ι-type, and their biosynthetic precursors (μ-type, ν-type), and these configurations dominate in natural red algae. Due to the dynamic and incomplete transformation characteristics of polysaccharide biosynthesis, it is usually difficult to obtain carrageenan with a single configuration from natural products; extracts are mostly hybrid molecules with multiple configuration units such as κ-, ι-, and λ-. Among them, λ-carrageenan is relatively rare in nature and often coexists with κ-carrageenan in the same algal body, making it difficult to extract high-purity λ-type components from red algae. The generational alternation of red algae has a decisive influence on the type of polysaccharide synthesized: for a few red algae that produce λ-carrageenan, the gametophyte stage mainly synthesizes κ- and ι-carrageenan and their precursors, while the tetrasporophyte stage mainly synthesizes λ-carrageenan. In existing studies, no λ-carrageenan signal was detected in any of the six commercial λ-carrageenan samples. They were actually hybrid carrageenan with κ-, ι- and (partial) ν- units, which further confirms the scarcity of high-purity λ-carrageenan from natural sources.

[0019] The marine red algae polysaccharide extract exhibits structural characteristics significantly different from known κ-type, ι-type, or λ-type carrageenan, representing a κ / ι / μ / ν / λ hybrid carrageenan with a high proportion of λ-carrageenan structural units. This high λ-configuration percentage results in a higher degree of sulfation (~34%), a key structural basis for its significant bioactivity. The presence of 3,6-lactone galactose in the main component of this marine red algae polysaccharide extract is related to the specific conformation and bioactivity of red algal galactan. In summary, the main components of this marine red algae polysaccharide extract possess a unique hybrid structure, particularly its high λ-configuration percentage and the resulting high sulfation characteristics, demonstrating significant advantages in anti-inflammatory and immunomodulatory effects, providing a solid structural basis for its application as a novel therapeutic agent or functional ingredient.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects: 1. The red algae polysaccharide extract provided by this invention has a sulfate content of 20-40%, and its main component is a highly sulfated galactan with a λ-type carrageenan structural unit accounting for 10-50%.

[0021] 2. The red algae polysaccharide extract provided by this invention has anti-inflammatory and antioxidant activities, which can improve the skin appearance and pathological features of AD and reduce serum IgE.

[0022] 3. The red algae polysaccharide extract from marine red algae provided by this invention exhibits outstanding safety potential. In vitro cytotoxicity experiments demonstrate its good safety at effective concentrations. In animal experiments, compared with potent glucocorticoids, the red algae polysaccharide extract from marine red algae provided by this invention produced significant therapeutic effects without observing typical hormone-like systemic side effects leading to atrophy of immune organs (spleen, lymph nodes), indicating superior long-term safety.

[0023] 4. The red algae polysaccharide extract provided by this invention can be developed into a topical drug for treating AD, or used as an active ingredient to develop cosmetics or skin care products with anti-inflammatory, repairing, and soothing functions, meeting the needs of daily skin care and adjunctive treatment.

[0024] 5. The red algae polysaccharide extract provided by this invention is derived from marine red algae, and the preparation process is mature, environmentally friendly, and has industrialization potential. Attached Figure Description

[0025] Figure 1 The image shows an HPLC chromatogram of the monosaccharide composition of the red algae polysaccharide extract (GRB-H) in an embodiment of the present invention.

[0026] Figure 2 The NMR spectrum of the red algae polysaccharide extract (GRB-H) in this embodiment of the invention is shown, where a: NMR- 1 H: Full spectrum, b: NMR- 1 H: Local magnified spectrum; c: NMR- 13 C full spectrum, d: NMR- 13 C Local magnification spectrum.

[0027] Figure 3 This is a schematic diagram illustrating the effect of the red algae polysaccharide extract (GRB-H) on the cytotoxicity of Raw 264.7 cells in an embodiment of the present invention.

[0028] Figure 4 This is a schematic diagram illustrating the effects of marine red algae polysaccharide extract (GRB-H) on NO and inflammatory factor release in Raw 264.7 cells in an embodiment of the present invention; where a: NO release; b: TNF-α release; c: IL-6 release; ****p <0.0001, *** p <0.001, ** p <0.01, * p <0.05 compared to the control group; #### p <0.0001, ### p <0.001 Comparison between Blank and Control groups.

[0029] Figure 5 This is a schematic diagram illustrating the effect of red algae polysaccharide extract (GRB-H) on ROS (reactive oxygen species) generation in Raw 264.7 cells in an embodiment of the present invention (****). p <0.0001, *** p <0.001 compared with the control group; #### p <0.0001 (Comparison between Blank and Control groups).

[0030] Figure 6 This invention illustrates the effect of red algae polysaccharide extract (GRB-H) on DNCB-induced atopic dermatitis symptoms in mice. Wherein, a: modeling and drug administration flowchart; b: mouse ear and back photographs; c: dermatitis severity score; d: back skin thickness; e: right ear thickness; f: serum total IgE level; g: spleen index; h: inguinal lymph node weight. p <0.0001, *** p <0.001, ** p <0.01, * p <0.05 compared to the control group; #### p <0.0001, ### p <0.001 Comparison between Blank and Control groups.

[0031] Figure 7 This invention illustrates the effect of marine red algae polysaccharide extract (GRB-H) on the histopathology of DNCB-induced atopic dermatitis in mice; wherein, a: hematoxylin-eosin (HE) stained sections; b: epidermal thickness; c: toluidine blue (TB) stained sections; d: mast cell count. p <0.0001, *** p <0.001, ** p <0.01, * p <0.05 compared to the control group;#### p <0.0001, ### p <0.001 Comparison between Blank and Control groups. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the following detailed description, in conjunction with specific embodiments and accompanying drawings, further illustrates the invention. Obviously, the described embodiments are only a portion, not all, of the embodiments disclosed in this invention. All other embodiments obtained by those skilled in the art based on the embodiments disclosed in this invention without inventive effort are within the scope of protection of this invention.

[0033] The present invention is described in detail below with reference to the embodiments, but the present invention is not limited to these embodiments. Unless otherwise specified, the raw materials and catalysts used in the embodiments of the present invention were purchased commercially. Unless otherwise specified, all concentration percentages in the present invention are mass percentages.

[0034] Instruments: DL-5 low-speed, high-capacity centrifuge (Shanghai Anting Scientific Instrument Factory); Centrifuge 5430R multi-functional centrifuge (Eppendorf, USA); BS2000S electronic analytical balance (Beijing Sartorius Balance Co., Ltd.); Bio-Tek Elx808 multi-functional microplate reader (BioTek, USA); Agilent 1260 high-performance liquid chromatograph; Agilent NovoCyte 3000 flow cytometer; laminar flow hood (Shanghai Lishen Scientific Instrument Co., Ltd.); CO2 cell incubator (Thermo Fisher Scientific, USA); inverted microscope (OLYBUS, Japan); QuantStudio3 RT-qPCR instrument (Thermo Fisher Scientific).

[0035] Example 1: Marine Red Algae Gigartina radula Preparation and structural characterization of polysaccharide extracts Preparation of polysaccharide extracts: Gigartina radula After washing, drying, and pulverizing, the algal powder was added to pure water at a ratio of 1:30 (m / v) and extracted at 80℃ for 2 h. The mixture was then centrifuged, and the supernatant was collected. The residue was then mixed with pure water at a ratio of 1:30 (m / v), and the above operation was repeated. The two extracts were combined and concentrated to 1 / 3 of the original volume. Four times the volume of 95% ethanol was added, and the mixture was allowed to precipitate overnight. The precipitate was collected by centrifugation, redissolved, ultrafiltered (>30 kDa), concentrated, and freeze-dried to obtain marine red algae. Gigartina radulaFor the sake of convenience in the examples, the polysaccharide extract is named GRB-H.

[0036] Monosaccharide composition determination: The monosaccharide composition in polysaccharide samples was determined by PMP pre-column derivatization high performance liquid chromatography.

[0037] Sulfate content determination: The sulfate content in GRB-H was determined by the gelatin-barium chloride method.

[0038] 3,6-Galactose content determination: The DA ring content in GRB-H was determined by the resorcinol method.

[0039] Viscosity determination: The viscosity of the samples before and after pretreatment was determined using a rotational viscometer. Appropriate amounts of the sample were weighed and mixed with water to prepare a 1.5% (w / w) solution. The solution was stirred at 60°C until completely dissolved. At the same temperature, a suitable rotor and rotation speed were selected for viscosity determination. The same sample was measured three times consecutively, and the average value was taken.

[0040] Nuclear magnetic resonance (NMR) spectroscopy analysis: 70 mg of GRB-H was dissolved in water to prepare a sample solution of 10 mg / mL. H₂SO₄ was added to a final concentration of 0.1 mol / L, and the solution was degraded at 60℃ for 0.5 h. Subsequently, neutralization, ultrafiltration (>30 kDa), and lyophilization were performed. Using DSS as an internal standard, NMR (600 MHz) was conducted at 25℃ to obtain high-resolution NMR spectra. 1 H NMR and 13 C NMR spectrum.

[0041] The yield of GRB-H was 37.98%, with a sulfate content of 34.35%, a 3,6-lactogalactose content of 24.41%, and a viscosity of 182.9 mPa·s. The monosaccharide composition results are as follows: Figure 1 As shown, GRB-H is composed of two monosaccharides: Glc (9.64%) and Gal (90.36%). The NMR spectrum of GRB-H is shown below. Figure 2As shown, the peaks in the 3-6 ppm range are sugar ring peaks. A characteristic ι-DA2S peak is present at 5.28 ppm, a κ-DA peak at 5.09 ppm, a ν-D2S / 6S peak at 5.52 ppm, a μ-D6S peak at 5.23 ppm, and a λ-D2S / 6S peak at 5.58 ppm, indicating that GRB-H is composed of carrageenan with five structures: κ, ι, μ, ν, and λ. The integrated area of ​​the internal standard peak DSS is recorded as 1. Normalized analysis was performed on the integrated areas of the three carrageenan structures, and their respective proportions were recorded as relative contents. In GRB-H, the κ-carrageenan structure accounts for 36.81%, the ι-carrageenan structure for 12.53%, the μ-carrageenan structure for 7.18%, the ν-carrageenan structure for 13.05%, and the λ-carrageenan structure for 30.42%.

[0042] Example 2 Cytotoxicity Evaluation Raw 264.7 cells in good growth condition were used at a rate of 5 × 10⁻⁶. 3 Cells were seeded at a density of 200 μL of complete culture medium per well in 96-well plates and incubated in a 5% CO2 incubator for at least 12 h. After complete cell adhesion, the supernatant was discarded, and pre-prepared GRB-H sample in complete culture medium was added. Sample concentrations were set at 0.05 mg / mL, 0.1 mg / mL, 0.2 mg / mL, and 0.4 mg / mL, with an equal volume of blank culture medium as a control. After 24 h of treatment, 20 μL of CCK8 assay reagent was added to each well, and the plates were incubated in a 5% CO2 incubator for 2 h in the dark. The absorbance at 450 nm was then measured.

[0043] The results are as follows Figure 3 As shown, when the concentration is less than or equal to 0.4 mg / mL, GRB-H has no significant toxic effect on Raw 264.7 cells.

[0044] Example 3 Evaluation of Cellular Anti-inflammatory Activity Raw 264.7 cells in good growth condition were used at a rate of 5 × 10⁻⁶. 4Cells were seeded at a density of 200 μL of complete culture medium per well in 96-well plates and incubated in a 5% CO2 incubator for at least 12 h. After complete cell adhesion, the supernatant was discarded, and GRB-H sample prepared in advance using complete culture medium containing 1 μg / mL LPS was added. Sample concentrations were set at 0.05 mg / mL, 0.1 mg / mL, 0.2 mg / mL, and 0.4 mg / mL, respectively. An equal volume of blank culture medium and complete culture medium containing only 1 μg / mL LPS were set as controls. After 24 h of treatment, the NO concentration in the supernatant was measured using a Nitric oxide assay kit. Cell supernatant was collected, and the concentrations of TNF-α and IL-6 inflammatory factors released by the cells were detected using an ELISA kit.

[0045] The results are as follows Figure 4 As shown, 0.05-0.4 mg / mL GRB-H can significantly inhibit the production of NO and the release of inflammatory factors, exhibiting anti-inflammatory activity.

[0046] Example 4 Evaluation of cellular antioxidant activity Raw 264.7 cells in good growth condition were used at a rate of 2.5 × 10⁻⁶. 5 Cells were seeded per well in 6-well plates and incubated with 10 μg / mL LPS for 12 h after adherence to simulate the inflammatory microenvironment of Alzheimer's disease (AD) skin. RAW 264.7 cells were then co-cultured for 12 h in complete medium containing hydrogen peroxide (50 μM) and GRB-H (0.4 mg / mL). The in vitro reactive oxygen species scavenging capacity of GRB-H was assessed using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) staining.

[0047] The results are as follows Figure 5 As shown, GRB-H at concentrations of 0.05–0.4 mg / mL can significantly inhibit ROS production, with 0.05 and 0.1 mg / mL GRB-H showing more pronounced inhibitory effects on ROS generation.

[0048] Example 5: Effect of GRB-H on symptoms of DNCB-induced atopic dermatitis in mice Thirty-six BALB / c female mice (20±2 g, 5 weeks old) were purchased from Jiangsu Jicui Pharmaceutical Biotechnology Co., Ltd. and kept in an environment with a temperature of 18–24°C and a relative humidity of 50%–70%. All animal experiments were reviewed and approved by the Ethics Committee of Ocean University of China (Animal Breeding License: SCXK-2023-0009, No. OUC-SMP-2025-08-04). These mice were systematically randomized into six different groups: normal control group (Blank), atopic dermatitis model group (Control), clobetasol propionate group (0.05% CCPO), low-dose GRB-H group (0.5% GRB-H), medium-dose GRB-H group (1% GRB-H), and high-dose GRB-H group (1.5% GRB-H).

[0049] To establish a mouse model of atopic dermatitis, the hair on the back of the mice was shaved, covering an area of ​​approximately 4 square centimeters. DNCB solution (acetone: olive oil = 3:1) was applied topically to the right ear and back. The Blank group was treated with the same amount of physiological saline. From day 8 to day 19, the treatment group received 200 μL of GRB-H applied to the abdomen and ears, while the Blank and Control groups received the same amount of physiological saline, and the 0.05% CCPO group received 0.05% CCPO.

[0050] Atopic dermatitis severity was assessed on days 2, 3, 6, 8, 9, 11, 14, 17, and 20. On day 20, all mice were anesthetized with isoflurane and euthanized. Ear tissue, dorsal skin lesions, spleen, inguinal lymph nodes, and serum samples were collected. The thickness of the right ear and dorsal skin lesions was measured using calipers. Spleen and lymph node weights were recorded, and the spleen index was defined as the ratio of spleen weight (mg) to body weight (g). Serum total IgE levels were determined using the Mouse IgE ELISA Kit.

[0051] After assessing the phenotypic parameters of the mice, histological analysis was then performed on the dorsal skin lesions. The lesion tissue was first fixed in 4% formalin solution and then embedded in paraffin blocks. The tissue was cut into 6 mm sections and stained with gentian violet-isosin (H&E) and thallium blue (TB) for histological evaluation. Images were quantitatively analyzed using ImageJ software.

[0052] The results are as follows Figure 6 , Figure 7 As shown in the figure. Compared with the control group, DNCB stimulation caused a significant increase in the thickness of the right ear in mice, and typical AD symptoms such as skin crusting, erythema, and edema appeared, with a significant increase in skin thickness. However, after local treatment with different concentrations of GRB-H or the positive control drug clobetasol propionate (CCPO), the above-mentioned skin lesions were significantly improved. Figure 6b, c). Compared with the model group, the serum IgE level in the GRB-H treatment group was significantly lower in a concentration-dependent manner; the serum IgE level in the positive control drug CCPO group was not significantly different from that in the model group. Figure 6 f). The lymph node weight and spleen index of the model group mice were significantly increased, suggesting compensatory proliferation of immune organs caused by systemic inflammation, a typical manifestation of Th2 immune dominance activation, immune cell proliferation, and systemic spread of inflammation. Compared with the control group, the spleen index of the model group was slightly increased (without statistical significance), while the spleen index of the 1.5% GRB-H group showed a decreasing trend (f). Figure 6 g). The lymph nodes in the model group were significantly enlarged, while the lymph node weight was significantly reduced in the 1% and 1.5% GRB-H treatment groups (g). Figure 6 (h). It is noteworthy that the spleen and lymph nodes in the CCPO group showed significant atrophy, which may be related to its systemic side effects as a super-potent glucocorticoid, such as inducing lymphocyte apoptosis and inhibiting lymphocyte function.

[0053] Histopathological analysis showed that the skin of DNCB-induced AD mice exhibited typical lesions such as hyperkeratosis, epidermal thickening, and inflammatory cell infiltration. Figure 7 a). Hematoxylin-eosin (HE) staining showed that both CCPO and GRB-H treatments significantly improved epidermal thickening ( Figure 7 a, b). Toluidine blue (TB) staining showed that topical application of GRB-H significantly reduced mast cell infiltration in the skin. Figure 7 c, d).

[0054] Under the conditions of this experiment, the sample "marine red algae" Gigartina radula The polysaccharide extract (GRB-H) was tested at the following concentrations: cell viability assay, anti-inflammatory activity evaluation, antioxidant activity evaluation, and effect on DNCB-induced atopic dermatitis symptoms in mice. The results showed that the extract had anti-inflammatory, antioxidant, and therapeutic effects on atopic dermatitis.

[0055] The above description is merely an embodiment of the present invention, and the scope of protection of the present invention is not limited to these specific embodiments, but is determined by the claims of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principle of the present invention should be included within the scope of protection of the present invention.

Claims

1. A marine red algae polysaccharide extract, characterized in that, This marine red algae polysaccharide extract is a heterozygous carrageenan-type galactan containing κ-carrageenan structural units, ι-carrageenan structural units, μ-carrageenan structural units, ν-carrageenan structural units, and λ-carrageenan structural units.

2. The marine red algae polysaccharide extract as described in claim 1, characterized in that, The heterocarrageenan-based galactomannan contains galactose and glucose, with a sulfate content of 20-40% and a 3,6-lactone galactose content of 20-50%.

3. The marine red algae polysaccharide extract as described in claim 1, characterized in that, The proportion of λ-carrageenan structural units is 10-50%.

4. The marine red algae polysaccharide extract as described in claim 1, characterized in that, This marine red algae polysaccharide extract is derived from marine red algae. Gigartina radula .

5. The marine red algae polysaccharide extract as described in claim 1, characterized in that, The marine red algae polysaccharide extract was prepared by extraction with purified water and precipitation with ethanol.

6. The marine red algae polysaccharide extract as described in claim 1, characterized in that, The viscosity of this marine red algae polysaccharide extract in a 1.5% aqueous solution at 60°C is 80-400 mPa·s.

7. The use of the marine red algae polysaccharide extract according to claim 1 in the preparation of products for the prevention, relief and / or treatment of atopic dermatitis or immune-related skin diseases.

8. The use of the marine red algae polysaccharide extract according to claim 1 in the preparation of anti-inflammatory and antioxidant products.

9. The use of the marine red algae polysaccharide extract according to claim 1 in the preparation of cosmetics or skin care products.

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