A review on fucoidan antitumor strategies: From a biological active agent to a structural component of fucoidan-based systems

Seaweed-derived fucoidans and rhamnan sulfates serve as potent anti-SARS-CoV-2 agents with potential for prophylaxis

Seaweeds represent a rich source of sulfated polysaccharides with similarity to heparan sulfate, a facilitator of myriad virus host cell attachment. For this reason, attention has been drawn to their antiviral activity, including the potential for anti-SARS-CoV-2 activity. We have identified and structurally characterized several fucoidan extracts, including those from different species of brown macroalga, and a rhamnan sulfate from a green macroalga species. A high molecular weight fucoidan extracted from Saccharina japonica (FSjRPI-27), and a rhamnan sulfate extracted from Monostroma nitidum (RSMn), showed potent competitive inhibition of spike glycoprotein receptor binding to a heparin-coated SPR chip. This inhibition was also observed in cell-based assays using hACE2 HEK-293 T cells infected by pseudotyped SARS-CoV-2 virus with IC50 values <1 μg/mL. Effectiveness was demonstrated in vivo using hACE2-transgenic mice. Intranasal administration of FSjRPI-27 showed protection when dosed 6 h prior to and at infection, and then every 2 days post-infection, with 100 % survival and no toxicity at 104 plaque-forming units per mouse vs. buffer control. At 5-fold higher virus dose, FSjRPI-27 reduced mortality and yielded reduced viral titers in bronchioalveolar fluid and lung homogenates vs. buffer control. These findings suggest the potential application of seaweed-based sulfated polysaccharides as promising anti-SARS-CoV-2 prophylactics.

Lipid metabolism regulation by dietary polysaccharides with different structural properties

Lipid metabolism plays an important role in energy homeostasis maintenance in response to stress. Nowadays, hyperlipidemia-related chronic diseases such as obesity, diabetes, atherosclerosis, and fatty liver pose significant health challenges. Dietary polysaccharides (DPs) have gained attention for their effective lipid-lowering properties. This review examines the multifaceted mechanisms that DPs employ to lower lipid levels in subjects with hyperlipidemia. DPs could directly inhibit lipid intake and absorption, promote lipid excretion, and regulate key enzymes involved in lipid metabolism pathways, including triglyceride and cholesterol anabolism and catabolism, fatty acid oxidation, and bile acid synthesis. Additionally, DPs indirectly improve lipid homeostasis by modulating gut microbiota composition and alleviating oxidative stress. Moreover, the lipid-lowering mechanisms of particular structural DPs (including β-glucan, pectin, glucomannan, inulin, arabinoxylan, and fucoidan) are summarized. The relationship between the structure and lipid-lowering activity of DPs is also discussed based on current researches. Finally, potential breakthroughs and future directions in the development of DPs in lipid-lowering activity are discussed. The paper could provide a reference for further exploring the mechanism of DPs for lipid regulations and utilizing DPs as lipid-lowering dietary ingredients.

Marine polysaccharides: Biological activities and applications in drug delivery systems

The ocean is the common home of a large number of marine organisms, including plants, animals, and microorganisms. Researchers can extract thousands of important bioactive components from the oceans and use them extensively to treat and prevent diseases. In contrast, marine polysaccharide macromolecules such as alginate, carrageenan, Laminarin, fucoidan, chitosan, and hyaluronic acid have excellent physicochemical properties, good biocompatibility, and high bioactivity, which ensures their wide applications and strong therapeutic potentials in drug delivery. Drug delivery systems (DDS) based on marine polysaccharides and modified marine polysaccharide molecules have emerged as an innovative technology for controlling drug distribution on temporal, spatial, and dosage scales. They can detect and respond to external stimuli such as pH, temperature, and electric fields. These properties have led to their wide application in the design of novel drug delivery systems such as hydrogels, polymeric micelles, liposomes, microneedles, microspheres, etc. In addition, marine polysaccharide-based DDS not only have smart response properties but also can combine with the unique biological properties of the marine polysaccharide base to exert synergistic therapeutic effects. The biological activities of marine polysaccharides and the design of marine polysaccharide-based DDS are reviewed. Marine polysaccharide-based responsive DDS are expected to provide new strategies and solutions for disease treatment.

Construction of quercetin-fucoidan nanoparticles and their application in cancer chemo-immunotherapy treatment

Fucoidan (FU), a natural marine polysaccharide, is an immunomodulator with great potential in tumor immunotherapy. In this work, a FU encapsulated nanoparticle named QU@FU-TS was developed, which contained the anticancer phytochemical quercetin (QU) and had the potential for cancer chemo-immunotherapy. QU@FU-TS were constructed through molecular self-assembly using green material tea saponin (TS) as the linking molecule. The molecular dynamics (MD) simulation showed that QU was bound to the hydrophobic tail of TS. At the same time, FU spontaneously assembled with the hydrophilic head of TS to form the outer layer of the QU@FU-TS. The molecular interactions between QU and TS were mainly π-stacking and hydrogen bonds. The bonding of FU and TS was maintained through the formation of multiple hydrogen bonds between the sulfate ester group and the hydroxy group. The inhibitory effects of QU@FU-TS on A549 cell proliferation were more potent than that by free QU. The antitumor activity of QU@FU-TS was mediated through various mechanisms, including the induction of oxidative stress, blocking cell cycle progression, and promoting cell apoptosis. Moreover, QU@FU-TS has been demonstrated to impede the proliferation and migration of cancer cells in vivo. The expression levels of macrophage surface markers increased under the treatment of QU@FU-TS, suggesting the potential of QU@FU-TS to serve as an immunotherapeutic agent by promoting macrophage activation.

An application of carbohydrate polymers-based surface-modified gold nanoparticles for improved target delivery to liver cancer therapy - A systemic review

Gold nanoparticles have been broadly investigated as cancer diagnostic and therapeutic agents. Gold nanoparticles are a favorable drug delivery vehicle with their unique subcellular size and good biocompatibility. Chitosan, agarose, fucoidan, porphyran, carrageenan, ulvan and alginate are all examples of biologically active macromolecules. Since they are biocompatible, biodegradable, and irritant-free, they find extensive application in biomedical and macromolecules. The versatility of these compounds is enhanced because they are amenable to modification by functional groups like sulfation, acetylation, and carboxylation. In an eco-friendly preparation process, the biocompatibility and targeting of GNPs can be improved by functionalizing them with polysaccharides. This article provides an update on using carbohydrate-based GNPs in liver cancer treatment, imaging, and drug administration. Selective surface modification of several carbohydrate types and further biological uses of GNPs are focused on.

Antitumor effects of polysaccharides from medicinal lower plants: A review

Cancer is one of the leading causes of death worldwide, yet the drugs currently approved for cancer treatment are associated with significant side effects, making it urgent to develop alternative drugs with low side effects. Polysaccharides are natural polymers with ketone or aldehyde groups, which are widely found in plants and have various biological activities such as immunomodulation, antitumor and hypolipidemic. The lower plants have attracted much attention for their outstanding anticancer effects, and many studies have shown that medicinal lower plant polysaccharides (MLPPs) have antitumor activity against various cancers and are promising alternatives with potential development in the food and pharmaceutical fields. Therefore, this review describes the structure and mechanism of action of MLPPs with antitumor activity. In addition, the application of MLPPs in cancer treatment is discussed, and the future development of MLPPs is explored.

Fucoidan Ameliorates Ferroptosis in Ischemia-reperfusion-induced Liver Injury through Nrf2/HO-1/GPX4 Activation

Background and Aims

Liver ischemia-reperfusion (IR) injury is a common pathological process in liver surgery. Ferroptosis, which is closely related to lipid peroxidation, has recently been confirmed to be involved in the pathogenesis of IR injury. However, the development of drugs that regulate ferroptosis has been slow, and a complete understanding of the mechanisms underlying ferroptosis has not yet been achieved. Fucoidan (Fu) is a sulfated polysaccharide that has attracted research interest due to its advantages of easy access and wide biological activity.

Methods

In this study, we established models of IR injury using erastin as an activator of ferroptosis, with the ferroptosis inhibitor ferrostatin-1 (Fer-1) as the control. We clarified the molecular mechanism of fucoidan in IR-induced ferroptosis by determining lipid peroxidation levels, mitochondrial morphology, and key pathways in theta were involved.

Results

Ferroptosis was closely related to IR-induced hepatocyte injury. The use of fucoidan or Fer-1 inhibited ferroptosis by eliminating reactive oxygen species and inhibiting lipid peroxidation and iron accumulation, while those effects were reversed after treatment with erastin. Iron accumulation, mitochondrial membrane rupture, and active oxygen generation related to ferroptosis also inhibited the entry of nuclear factor erythroid 2-related factor 2 (Nrf2) into the nucleus and reduced downstream heme oxygenase-1 (HO-1) and glutathione peroxidase 4 (GPX4) protein levels. However, fucoidan pretreatment produced adaptive changes that reduced irreversible cell damage induced by IR or erastin.

Conclusions

Fucoidan inhibited ferroptosis in liver IR injury via the Nrf2/HO-1/GPX4 axis.

Nature's soothing solution: Harnessing the potential of food-derived polysaccharides to control inflammation

Reducing inflammation by diet is a major goal for prevention or lowering symptoms of a variety of diseases, such as auto-immune reactions and cancers. Natural polysaccharides are increasingly gaining attention due to their potential immunomodulating capacity. Structures of those molecules are highly important for their effects on the innate immune system, cytokine production and secretion, and enzymes in immune cells. Such polysaccharides include β-glucans, pectins, fucoidans, and fructans. To better understand the potential of these immunomodulatory molecules, it is crucial to enhance dedicated research in the area. A bibliometric analysis was performed to set a starting observation point. Major pillars of inflammation, such as pattern recognition receptors (PRRs), enzymatic production of inflammatory molecules, and involvement in specific pathways such as Nuclear-factor kappa-B (NF-kB), involved in cell transcription, survival, and cytokine production, and mitogen-activated protein kinase (MAPK), a regulator of genetic expression, mitosis, and cell differentiation. Therefore, the outcomes from polysaccharide applications in those scenarios are discussed.

Current application and modification strategy of marine polysaccharides in tissue regeneration: A review

Marine polysaccharides (MPs) are exceptional bioactive materials that possess unique biochemical mechanisms and pharmacological stability, making them ideal for various tissue engineering applications. Certain MPs, including agarose, alginate, carrageenan, chitosan, and glucan have been successfully employed as biological scaffolds in animal studies. As carriers of signaling molecules, scaffolds can enhance the adhesion, growth, and differentiation of somatic cells, thereby significantly improving the tissue regeneration process. However, the biological benefits of pure MPs composite scaffold are limited. Therefore, physical, chemical, enzyme modification and other methods are employed to expand its efficacy. Chemically, the structural properties of MPs scaffolds can be altered through modifications to functional groups or molecular weight reduction, thereby enhancing their biological activities. Physically, MPs hydrogels and sponges emulate the natural extracellular matrix, creating a more conducive environment for tissue repair. The porosity and high permeability of MPs membranes and nanomaterials expedite wound healing. This review explores the distinctive properties and applications of select MPs in tissue regeneration, highlighting their structural versatility and biological applicability. Additionally, we provide a brief overview of common modification strategies employed for MP scaffolds. In conclusion, MPs have significant potential and are expected to be a novel regenerative material for tissue engineering.

Polysaccharide‑platinum complexes for cancer theranostics

Platinum anticancer drugs have been explored and developed in recent years to reduce systematic toxicities and resist drug resistance. Polysaccharides derived from nature have abundant structures as well as pharmacological activities. The review provides insights on the design, synthesis, characterization and associating therapeutic application of platinum complexes with polysaccharides that are classified by electronic charge. The complexes give birth to multifunctional properties with enhanced drug accumulation, improved tumor selectivity and achieved synergistic antitumor effect in cancer therapy. Several techniques developing polysaccharides-based carriers newly are also discussed. Moreover, the lasted immunoregulatory activities of innate immune reactions triggered by polysaccharides are summarized. Finally, we discuss the current shortcomings and outline potential strategies for improving platinum-based personalized cancer treatment. Using platinum-polysaccharides complexes for improving the immunotherapy efficiency represents a promising framework in future.

Anti-Hyperlipidemic Effect of Fucoidan Fractions Prepared from Iceland Brown Algae Ascophyllum nodosum in an Hyperlipidemic Mice Model

Ascophyllum nodosum, a brown algae abundantly found along the North Atlantic coast, is recognized for its high polysaccharide content. In this study, we investigated the anti-hyperlipidemic effect of fucoidans derived from A. nodosum, aiming to provide information for their potential application in anti-hyperlipidemic therapies and to explore comprehensive utilization of this Iceland brown seaweed. The crude fucoidan prepared from A. nodosum was separated using a diethylethanolamine column, resulting in two fucoidan fractions, AFC-1 and AFC-2. Both fractions were predominantly composed of fucose and xylose. AFC-1 exhibited a higher sulfate content of 27.8% compared to AFC-2 with 17.0%. AFC-2 was primarily sulfated at the hydroxy group of C2, whereas AFC-1 was sulfated at both the hydroxy groups of C2 and C4. To evaluate the anti-hyperlipidemic effect, a hyperlipidemia mouse model was established by feeding mice a high-fat diet. The effects of AFC-1, AFC-2, and the crude extract were investigated, with the drug atorvastatin used as a positive comparison. Among the different fucoidan fractions and doses, the high dose of AFC-2 administration demonstrated the most significant anti-hyperlipidemic effect across various aspects, including physiological parameters, blood glucose levels, lipid profile, histological analysis, and the activities of oxidative stress-related enzymes and lipoprotein-metabolism-related enzymes (p < 0.05 for the final body weight and p < 0.01 for the rest indicators, compared with the model group), and its effect is comparable to the atorvastatin administration. Furthermore, fucoidan administration resulted in a lower degree of loss in gut flora diversity compared to atorvastatin administration. These findings highlight the significant biomedical potential of fucoidans derived from A. nodosum as a promising therapeutic solution for hypolipidemia.

Fucoidan-Coated Silica Nanoparticles Promote the Differentiation of Human Mesenchymal Stem Cells into the Osteogenic Lineage

Silica nanoparticles (SiNPs) are widely used in biomedical applications, such as cancer therapy/diagnosis or tissue engineering and regenerative medicine. Herein, we synthesized SiNPs and modified them with sulfonic acid groups (by organosilylation followed by oxidation) or a sulfated polysaccharide (i.e., fucoidan, a seaweed biopolymer, by using electrostatic surface immobilization) due to the known capacity of the sulfonic/sulfate moieties to stabilize proteins and promote stem cell differentiation toward the osteogenic lineage. The developed pristine and functionalized nanoparticles were characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), showing the monodisperse size distribution (between 360 and 450 nm) and the success of the coating/functionalization with fucoidan or sulfonic groups. The developed SiNPs (at a concentration of 50 μg/mL) were assessed through their contact with SaOs2 cells evidencing their cytocompatibility. Furthermore, the osteogenic differentiation of bmMSCs was evaluated by the quantification of ALP activity, as well as the expression profile of osteogenic-related genes, such as Runx2, ALP, and OP. We found that the coating of the SiNPs with fucoidan induced the osteogenic differentiation of bmMSCs, being an effective mediator of bone regeneration.

Polysaccharides from marine biological resources and their anticancer activity on breast cancer

In recent decades, natural products from marine organisms have been widely studied for the treatment of various breast cancers. Among them, polysaccharides have been favored by researchers because of their good effects and safety. In this review, polysaccharides from marine algae including macroalgae and microalgae, chitosan, microorganisms such as marine bacteria and fungi, and starfish are addressed. Their anticancer activities on different breast cancers and action mechanisms are discussed in detail. In general, polysaccharides from marine organisms are potential sources of low side-effect and high efficiency anticancer drugs for development. However, further research on animals and clinical research are needed.

Fucoidan from Fucus vesiculosus Inhibits Inflammatory Response, Both In Vitro and In Vivo

Fucoidan has been reported to present diverse bioactivities, but each extract has specific features from which a particular biological activity, such as immunomodulation, must be confirmed. In this study a commercially available pharmaceutical-grade fucoidan extracted from Fucus vesiculosus, FE, was characterized and its anti-inflammatory potential was investigated. Fucose was the main monosaccharide (90 mol%) present in the studied FE, followed by uronic acids, galactose, and xylose that were present at similar values (3.8-2.4 mol%). FE showed a molecular weight of 70 kDa and a sulfate content of around 10%. The expression of cytokines by mouse bone-marrow-derived macrophages (BMDMs) revealed that the addition of FE upregulated the expression of CD206 and IL-10 by about 28 and 22 fold, respectively, in respect to control. This was corroborated in a stimulated pro-inflammatory situation, with the higher expression (60 fold) of iNOS being almost completely reversed by the addition of FE. FE was also capable of reverse LPS-caused inflammation in an in vivo mouse model, including by reducing macrophage activation by LPS from 41% of positive CD11C to 9% upon fucoidan injection. Taken together, the potential of FE as an anti-inflammatory agent was validated, both in vitro and in vivo.

Fucoidan mitigates gastric ulcer injury through managing inflammation, oxidative stress, and NLRP3-mediated pyroptosis

This study aimed to elucidate the gastro-protective effect of fucoidan against ethanol-induced gastric ulcer mediated via NLRP3-induced pyroptosis as an underlying mechanism, not yet assessed in prior research. Forty-eight male Albino mice were divided into six groups: Group I (normal control), group II (Ulcer/ethanol control), group III (Omeprazole + ethanol), group IV (fucoidan 25 mg + ethanol), group V (fucoidan 50 mg + ethanol) and group VI (fucoidan only). Fucoidan was administered orally for seven consecutive days followed by ulcer induction by a single oral dose of ethanol. Using colorimetric analysis, ELISA, qRT-PCR, histological assessment, and immunohistochemical studies, the results revealed that ethanol-induced ulcer exhibited an ulcer score of 42.5 ± 5.1 and a significant increase (p < 0.05) in malondialdehyde (MDA), nuclear factor kappa B (NF-κB), and interleukin 6 (IL-6) with a significant decrease in the gastro-protective mediators, prostaglandin E2 (PGE2), superoxide dismutase (SOD) and glutathione (GSH), accompanied with an increase in NLRP3, interleukin 1β (IL-1β), interleukin 18 (IL-18), caspase 1, caspase 11, gasdermin D, and toll-like receptor 4 (TLR4), compared with the normal control. Pre-treatment with fucoidan showed a comparable result with omeprazole. Additionally, pre-treatments elevated the levels of the gastro-protective mediators and lessened oxidative stress, relative to the positive control findings. Conclusively, fucoidan has a promising gastro-protective role by inhibiting inflammation and pyroptosis.

Comparison of anti-tumor activities and underlying mechanisms of glucuronomannan oligosaccharides and its sulfated derivatives on the hepatocarcinoma Huh7.5 cells

Hepatocellular carcinoma (HCC) is an aggressive tumor triggered by various factors such as virus infection and alcohol abuse. Glucuronomannan polysaccharide (Gx) is a subtype of fucoidans that possesses many bioactivities, but its anti-tumor activities in HCC have not been reported. In this paper, the anti-tumor effects of glucuronomannan oligosaccharides (Gx) and its sulfated derivatives (GxSy) on hepatocarcinoma Huh7.5 cells were investigated. The anti-proliferation, anti-metastasis activities, and underlying mechanism of Gx and GxSy on Huh7.5 cells were analyzed and compared by MTT, wound healing, transwell, and western blotting assays, respectively. Results showed that the best anti-proliferation effects were G4S1 and G4S2 among 13 drugs, which were 38.67% and 30.14%, respectively. The cell migration rates were significantly inhibited by G2S1, G4S2, G6S2, and unsulfated Gn. In addition, cell invasion effects treated with G4S1, G4S2, and G6S1 decreased to 48.62%, 36.26%, and 42.86%, respectively. Furthermore, sulfated G4 regulated the expression of (p-) FAK and MAPK pathway, and sulfated G6 down-regulated the MAPK signaling pathway while activating the PI3K/AKT pathway. On the contrary, sulfated G2 and unsulfated Gx had no inhibited effects on the FAK-mTOR pathway. These results indicated that sulfated Gx derivatives have better anti-tumor activities than unsulfated Gx in cell proliferation and metastasis process in vitro, and those properties depend on the sulfation group levels. Moreover, degrees of polymerization of Gx also played a vital role in mechanisms and bioactivities. This finding shows the structure-activity relationship for developing and applying the marine oligosaccharide candidates.

Cancer-targeted fucoidan‑iron oxide nanoparticles for synergistic chemotherapy/chemodynamic theranostics through amplification of P-selectin and oxidative stress

A combination of chemotherapy and chemodynamic therapy (CDT) is being developed to improve the theranostic efficacy and biological safety of current therapies. However, most CDT agents are restricted due to complex issues such as multiple components, low colloidal stability, carrier-associated toxicity, insufficient reactive oxygen species generation, and poor targeting efficacy. To overcome these problems, a novel nanoplatform composed of fucoidan (Fu) and iron oxide (IO) nanoparticles (NPs) was developed to achieve chemotherapy combined with CDT synergistic treatment with a facile self-assembling manner, and the NPs were made up of Fu and IO, in which the Fu was not only used as a potential chemotherapeutic but was also designed to stabilize the IO and target P-selectin-overexpressing lung cancer cells, thereby producing oxidative stress and thus synergizing the CDT efficacy. The Fu-IO NPs exhibited a suitable diameter below 300 nm, which favored their cellular uptake by cancer cells. Microscopic and MRI data confirmed the lung cancer cellular uptake of the NPs due to active Fu targeting. Moreover, Fu-IO NPs induced efficient apoptosis of lung cancer cells, and thus offer significant anti-cancer functions by potential chemotherapeutic-CDT.

A review focusing on the benefits of plant-derived polysaccharides for osteoarthritis

Osteoarthritis (OA) is a chronic joint disease characterized by progressive cartilage degeneration, which imposes a heavy physical and financial burden on the middle-aged and elderly population. As the pathogenesis of OA has not been fully elucidated, it is of great importance to develop targeted therapeutic or preventive medications. Traditional therapeutic drugs, such as non-steroidal anti-inflammatory drugs, steroids and opioids, have significant side effects, making the exploration for safe and effective alternative therapeutic drugs urgent. In recent years, many studies have reported the role of plant-derived polysaccharides in anti-inflammation, anti-oxidation, regulation of chondrocyte metabolism and proliferation, and cartilage protection, and have demonstrated their great potential in the treatment of OA. Therefore, by focusing on studies related to the intervention of plant-derived polysaccharides in OA, including in vivo and in vitro experiments, this review aimed to classify and summarize the existing research findings according to different mechanisms of action. In addition, reports on plant-derived polysaccharides as nanoparticles were also explored. Then, candidate monomers and theoretical bases were provided for the further development and application of novel drugs in the treatment of OA.

Bioactive Compounds from Brown Algae Alleviate Nonalcoholic Fatty Liver Disease: An Extensive Review

Nonalcoholic fatty liver disease (NAFLD) is one of the most prevalent chronic liver diseases. The increasing NAFLD incidences are associated with unhealthy lifestyles. Currently, there are no effective therapeutic options for NAFLD. Thus, there is a need to develop safe, efficient, and economic treatment options for NAFLD. Brown algae, which are edible, contain abundant bioactive compounds, including polysaccharides and phlorotannins. They have been shown to ameliorate insulin resistance, as well as hepatic steatosis, and all of these biological functions can potentially alleviate NAFLD. Accumulating reports have shown that increasing dietary consumption of brown algae reduces the risk for NAFLD development. In this review, we summarized the animal experiments and clinical proof of brown algae and their bioactive compounds for NAFLD treatment within the past decade. Our findings show possible avenues for further research into the pathophysiology of NAFLD and brown algae therapy.

Dietary fiber as a wide pillar of colorectal cancer prevention and adjuvant therapy

Colorectal cancer is the third most incident and second most lethal type of cancer worldwide. Lifestyle and dietary patterns are the key factors for higher disease development risk. The dietary fiber intake from fruits and vegetables, mainly formed by food hydrocolloids, can help to lower the incidence of this type of neoplasia. Different food polysaccharides have applications in anti-tumoral therapy, such as coadjuvant to mainstream drugs, carriage-like properties, or direct influence on tumoral cells. Some classes include inulin, β-glucans, pectins, fucoidans, alginates, mucilages, and gums. Therefore, it is fundamental to discuss colorectal cancer mechanisms and the roles played by different polysaccharides in intestinal health. Genetic, environmental, and immunological modulation of mutated pathways regarding colorectal cancer has been explored before. Microbial diversity, byproduct formation (primarily short-chain fatty acids), inflammatory profile control, and tumoral mutated pathways regulation are thoroughly explored mechanisms by which dietary fiber sources influence a healthy gut ambiance.

Marine macroalgae polysaccharides-based nanomaterials: an overview with respect to nanoscience applications

Background

Exploration of marine macroalgae poly-saccharide-based nanomaterials is emerging in the nanotechnology field, such as wound dressing, water treatment, environmental engineering, biosensor, and food technology.

Main body

In this article, the current innovation and encroachments of marine macroalgae polysaccharide-based nanoparticles (NPs), and their promising opportunities, for future prospect in different industries are briefly reviewed. The extraction and advancement of various natural sources from marine polysaccharides, including carrageenan, agarose, fucoidan, and ulvan, are highlighted in order to provide a wide range of impacts on the nanofood technology. Further, seaweed or marine macroalgae is an unexploited natural source of polysaccharides, which involves numerous different phytonutrients in the outermost layer of the cell and is rich in sulphated polysaccharides (SP), SP-based nanomaterial which has an enhanced potential value in the nanotechnology field.

Conclusion

At the end of this article, the promising prospect of SP-based NPs and their applications in the food sector is briefly addressed.

Fucoidan, as an immunostimulator promotes M1 macrophage differentiation and enhances the chemotherapeutic sensitivity of capecitabine in colon cancer

Chemotherapy resistance is one of the most critical challenges in colorectal cancer (CRC) treatment. The occurrence and development of chemotherapy resistance closely related to the tumor immune microenvironment (TIME). As the most important immunosuppressive immune cells infiltrating into the TIME, macrophages are essential for chemotherapy resistance in CRC treatment. In this study, we found that a kind of fucoidan (FPS1M) induced macrophages differentiation to the M1 phenotype, and this transformation promoted cancer cells apoptosis both in vitro and in vivo. TNFα is a key mediator of FPS1M-induced tumorcidal activity of macrophages. Mechanistically, as a stimulator of TLR4, FPS1M enhanced macrophages glycolysis and regulated macrophages differentiation to the M1 phenotype by the activation of TLR4 mediated PI3K/AKT/mTOR signaling axis. In addition, FPS1M improved the immunosuppressed tumor microenvironment by increasing the infiltration of M1 macrophages in tumor tissue, which was conducive to improving the sensitivity of tumor to chemotherapy. Collectively, our findings demonstrated that FPS1M has the great potential to be used in tumor immunotherapy. The results also suggested that the combination of FPS1M with capecitabine is an alternative therapy method for colon cancer.

Occurrence of different fucoidanase genes in Flavobacterium sp. SW and enzyme characterization

Fucoidans are hetero-sulfated polysaccharides that are widely distributed in brown algae and have been extensively studied for their various biological activities. The structure-function relationship of fucoidans remains unclear but can be studied using fucoidan-degrading enzymes (fucoidanases). Here, we isolated and identified Flavobacterium sp. SW as a microbial strain that can grow on fucoidan from Cladosiphon okamuranus as the sole carbon source. Genomic analysis of this strain revealed the presence of two genes, swfct and swfcn2, that are homologous to fct114 from Luteolibacter algae H18 and fcnA from Psychromonas sp. SW5A, respectively. The gene products were produced in Escherichia coli and showed significantly different specificities for fucoidan. Swfct catalyzed the degradation of deacetylated fucoidan from C. okamuranus, and Swfcn2 degraded fucoidans from Saccharina sculpera and Macrocystis pyrifera. The general properties of Swfct were examined by measuring the amounts of reducing ends produced by the enzymatic reaction, and the enzyme properties of Swfcn2 were evaluated by carbohydrate-polyacrylamide gel electrophoresis. Our findings indicate that one microbial strain can harbor genes encoding two different types of fucoidanases.

Comparison of in vitro and in vivo antioxidant activities of commercial fucoidans from Macrocystis pyrifera, Undaria pinnatifida, and Fucus vesiculosus

Antioxidants fucoidans from three seaweeds, Undaria pinnatifida (FUP), Macrocystis pyrifera (FMP) and Fucus vesiculosus (FFV) are sold commercially. However, it is unclear which fucoidan is the most potent antioxidant. Therefore, our objective was to compare the antioxidant activities of these fucoidans. For this purpose, six in vitro antioxidant tests were used, total antioxidant capacity, hydroxyl radical scavenging assay, ferrous and cupric chelating assay, reducing power and H2O2 scavenging assay. The data showed that the fucoidans had a low capacity to donate electrons, and a low capacity to chelate metals. The best activity obtained was in the scavenging of hydroxyl radical. When macrophages were exposed to H2O2 and fucoidans, MTT and live/dead assays showed that all fucoidans protected cells from oxidative damage. The survival rate of zebrafish embryos was significantly higher when exposed to H2O2 and fucoidans than H2O2 alone. In summary, the fucoidans evaluated were ranked according to their antioxidant activity as follows: FMP > FFV > FUP, and the results suggest that these fucoidans, mainly FMP, can be used in the formulation of medicines/foods.

Fucoidan inhibits EGFR redistribution and potentiates sorafenib to overcome sorafenib-resistant hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths worldwide. Although sorafenib is a standard first-line molecule-targeted drug against advanced HCC, the drug resistance development and adverse side effects usually limit its efficacy. This study investigated the effect of fucoidan on the sorafenib sensitivity of sorafenib-resistant human HCC cell line HepG2-SR established by long-time exposure of HepG2 to sorafenib. We demonstrated fucoidan combined with sorafenib synergistically promoted apoptosis and cell cycle arrest whereas inhibited cell migration in HepG2-SR cells. This combination treatment effectively suppressed the cellular epithelial growth factor receptor (EGFR) nuclear distribution and downstream gene transcription. Interestingly, fucoidan bound the cell surface EGFR, dampening EGFR translocation to lipid raft and further nuclear distribution, restoring the sorafenib sensitivity in HepG2-SR cells. Blocking fucoidan-EGFR interaction using EGFR antibody restrained the enhanced anti-tumor effects upon the combined administration. Besides, EGFR knockdown abolished the combination treatment-improved anti-tumor efficacy. This combination also suppressed in vivo xenograft tumor growth in nude mice. Our present study uncovered that fucoidan overcame sorafenib resistance in HCC via its interaction with cell membrane EGFR and further suppression of EGFR redistribution and downstream signaling in sorafenib-resistant cells. Overall, current results suggest that simultaneous treatment of fucoidan and sorafenib might serve as a potential therapeutic strategy against sorafenib-resistant HCC.

A new polysaccharide from Caulerpa chemnitzia induces molecular shifts of immunomodulation on macrophages RAW264.7

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CCP showed significant immunomodulatory effects.

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CCP raising the level of NO, TNF-α, and IL-6 of macrophages RAW264.7.

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Investigation on the metabolites and genes changes in CCP-induced RAW264.7.

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Potential immunostimulatory mechanism of CCP on RAW264.7 was elucidated.

Investigation on Caulerpa chemnitzia polysaccharides led to the finding of a new polysaccharide (CCP). The basic components of CCP were the total sugar (59.18% ± 0.57%), the uronic acids (36.75% ± 0.28%) and the sulfate (42.50% ± 0.42%), in total content. The physicochemical analysis revealed that CCP was a heteropolysaccharide with a molecular weight of 321.6 KDa, and composed of arabinose, fucose, glucose, mannose, galactose, xylose, fructose, ribose, glucuronic acid and galacturonic acid. The immunomodulatory assay showed that CCP played an important role in activating cell viability, the nitric oxide product and cytokines (IL-6 and TNF-α) secretion. Furthermore, the transcript-metabolic analysis displayed a total of 7692 differentially expressed genes (DEGs) and 95 differentially accumulated metabolites (DAMs), and revealed that CCP may play an immunomodulatory effect by activating NF-κB signaling pathway and arachidonic acid metabolism pathway. These findings will provide a basic understanding to further investigation of Caulerpa polysaccharides.

Impacts of Oxidative Stress and PI3K/AKT/mTOR on Metabolism and the Future Direction of Investigating Fucoidan-Modulated Metabolism

The critical factors for regulating cancer metabolism are oxidative stress and phosphoinositide-3-kinase/AKT serine-threonine kinase/mechanistic target of the rapamycin kinase (PI3K/AKT/mTOR). However, the metabolic impacts of oxidative stress and PI3K/AKT/mTOR on individual mechanisms such as glycolysis (Warburg effect), pentose phosphate pathway (PPP), fatty acid synthesis, tricarboxylic acid cycle (TCA) cycle, glutaminolysis, and oxidative phosphorylation (OXPHOS) are complicated. Therefore, this review summarizes the individual and interacting functions of oxidative stress and PI3K/AKT/mTOR on metabolism. Moreover, natural products providing oxidative stress and PI3K/AKT/mTOR modulating effects have anticancer potential. Using the example of brown algae-derived fucoidan, the roles of oxidative stress and PI3K/AKT/mTOR were summarized, although their potential functions within diverse metabolisms were rarely investigated. We propose a potential application that fucoidan may regulate oxidative stress and PI3K/AKT/mTOR signaling to modulate their associated metabolic regulations. This review sheds light on understanding the impacts of oxidative stress and PI3K/AKT/mTOR on metabolism and the future direction of metabolism-based cancer therapy of fucoidan.

Determination of the structure and in vitro anticancer activity of fucan from Saccharina dentigera and its derivatives

The fucoidan SdeF was isolated from brown alga Saccharina dentigera. The structure of the obtained polysaccharide was studied by chemical methods, NMR spectroscopy of the fully and partially desulfated derivatives, and mass spectrometry of the fucoidan fragments, labeled with 18O. The SdeF was shown to be sulfated (40%) 1,3-linked α-L-fucan, with branches at C2. The sulfate groups were found at positions C2 and C4. Derivatives SdeFDS and SdeFPL were obtained by solvolytic desulfation and autohydrolysis of SdeF, respectively. According to 13C NMR data, SdeFDS is 1,3-linked α-L-fucan, while SdeFPL is 4-sulfated 1,3-linked α-L-fucan. Native fucoidan SdeF was shown to be a non-toxic anticancer substance in the model of human malignant melanoma RPMI-7951, colorectal adenocarcinoma HCT-116, and small intestine adenocarcinoma HuTu 80 cells. The partial desulfation of SdeF at C2 and/or the reduction of its Mw, from 229 to 28 kDa, decreased the anticancer activity; complete removal of the sulfated groups and/or Mw reduction to 4.7 kDa further reduced the effect of this polysaccharide.

Antiviral Polymers: A Review

Polymers, due to their high molecular weight, tunable architecture, functionality, and buffering effect for endosomal escape, possess unique properties as a carrier or prophylactic agent in preventing pandemic outbreak of new viruses. Polymers are used as a carrier to reduce the minimum required dose, bioavailability, and therapeutic effectiveness of antiviral agents. Polymers are also used as multifunctional nanomaterials to, directly or indirectly, inhibit viral infections. Multifunctional polymers can interact directly with envelope glycoproteins on the viral surface to block fusion and entry of the virus in the host cell. Polymers can indirectly mobilize the immune system by activating macrophages and natural killer cells against the invading virus. This review covers natural and synthetic polymers that possess antiviral activity, their mechanism of action, and the effect of material properties like chemical composition, molecular weight, functional groups, and charge density on antiviral activity. Natural polymers like carrageenan, chitosan, fucoidan, and phosphorothioate oligonucleotides, and synthetic polymers like dendrimers and sialylated polymers are reviewed. This review discusses the steps in the viral replication cycle from binding to cell surface receptors to viral-cell fusion, replication, assembly, and release of the virus from the host cell that antiviral polymers interfere with to block viral infections.

In Vitro and In Vivo Dendritic Cell Immune Stimulation Effect of Low Molecular Weight Fucoidan from New Zealand Undaria pinnatifida

Low molecular weight fucoidan (LMWF) has been reported to have immunomodulation effects through the increase of the activation and function of macrophages. In this study, the regulating effect of LMWF from Undaria pinnatifida grown in New Zealand on dendritic cells (DCs) was investigated. We discovered that LMWF could stimulate DCs' maturation and migration, as well as CD4+ and CD8+ T cells' proliferation in vitro. We proved that this immune promoting activity is activated through TLR4 and its downstream MAPK and NF-κB signaling pathways. Further in vivo (mouse model) investigation showed that LMWF has a strong immunological boosting effect, such as facilitating the proliferation of immune cells and increasing the index of immune organs. These findings suggest that LMWF has a positive immunomodulatory effect and is a promising candidate to supplement cancer immunotherapy.

Addressing the Needs of the Rapidly Aging Society through the Development of Multifunctional Bioactive Coatings for Orthopedic Applications

The unprecedented aging of the world's population will boost the need for orthopedic implants and expose their current limitations to a greater extent due to the medical complexity of elderly patients and longer indwelling times of the implanted materials. Biocompatible metals with multifunctional bioactive coatings promise to provide the means for the controlled and tailorable release of different medications for patient-specific treatment while prolonging the material's lifespan and thus improving the surgical outcome. The objective of this work is to provide a review of several groups of biocompatible materials that might be utilized as constituents for the development of multifunctional bioactive coatings on metal materials with a focus on antimicrobial, pain-relieving, and anticoagulant properties. Moreover, the review presents a summary of medications used in clinical settings, the disadvantages of the commercially available products, and insight into the latest development strategies. For a more successful translation of such research into clinical practice, extensive knowledge of the chemical interactions between the components and a detailed understanding of the properties and mechanisms of biological matter are required. Moreover, the cost-efficiency of the surface treatment should be considered in the development process.

A Transcriptome Sequencing Study on Genome-Wide Gene Expression Differences of Lung Cancer Cells Modulated by Fucoidan

Fucoidan has received increasing attention in anti-(lung) tumors. However, the effect of fucoidan on the gene changes of lung cancer cells (LCCs) has not been examined systematically. Herein, we investigate the effect of fucoidan on the phenotypes of LCCs and their gene expression by transcriptome sequencing analysis. The phenotypes of LCCs are significantly inhibited by fucoidan. Importantly, compared to LCCs, 1 mg/ml fucoidan has no effect on the phenotypes of normal cells. Further, 6,930 differentially expressed genes (DEGs) in the transcriptome of LCCs (3,501 up-regulated and 3,429 down-regulated genes) are detected via RNA-sequencing between the fucoidan and control groups. Gene Ontology analysis confirms that DEGs are reflected in DNA replication, cell-substrate junction, regulation of cell cycle phase transition, apoptosis, focal adhesion, cadherin binding, and cell adhesion molecule binding. Thus, our findings on the transcriptomic level highlight the therapeutic potential of fucoidan for lung cancer treatment.

Polysaccharides as Potential Anti-tumor Biomacromolecules —A Review

Cancer, as one of the most life-threatening diseases, has attracted the attention of researchers to develop drugs with minimal side effects. The bioactive macromolecules, such as the polysaccharides, are considered the potential candidates against cancer due to their anti-tumor activities and non-toxic characteristics. The present review provides an overview on polysaccharides' extraction, isolation, purification, mechanisms for their anti-tumor activities, structure-activity relationships, absorption and metabolism of polysaccharides, and the applications of polysaccharides in anti-tumor therapy. Numerous research showed extraction methods of polysaccharides had a significant influence on their activities. Additionally, the anti-tumor activities of the polysaccharides are closely related to their structure, while molecular modification and high bioavailability may enhance the anti-tumor activity. Moreover, most of the polysaccharides exerted an anti-tumor activity mainly through the cell cycle arrest, anti-angiogenesis, apoptosis, and immunomodulation mechanisms. Also, recommendations were made to utilize the polysaccharides against cancer.

Antiviral Activities of Algal-Based Sulfated Polysaccharides

An antiviral agent is urgently needed based on the high probability of the emergence and re-emergence of future viral disease, highlighted by the recent global COVID-19 pandemic. The emergence may be seen in the discovery of the Alpha, Beta, Gamma, Delta, and recently discovered Omicron variants of SARS-CoV-2. The need for strategies besides testing and isolation, social distancing, and vaccine development is clear. One of the strategies includes searching for an antiviral agent that provides effective results without toxicity, which is well-presented by significant results for carrageenan nasal spray in providing efficacy against human coronavirus-infected patients. As the primary producer of sulfated polysaccharides, marine plants, including macro- and microalgae, offer versatility in culture, production, and post-isolation development in obtaining the needed antiviral agent. Therefore, this review will describe an attempt to highlight the search for practical and safe antiviral agents from algal-based sulfated polysaccharides and to unveil their features for future development.

Novel ROS-responsive marine biomaterial fucoidan nanocarriers with AIE effect and chemodynamic therapy

Chemodynamic therapy (CDT) has been widely used in the treatment of many kinds of tumors, which can effectively induce tumor cell apoptosis by using produced reactive oxygen species (ROS). In this paper, ROS-sensitive multifunctional marine biomaterial natural polysaccharide nanoparticles were designed. Aggregation-induced emission (AIE) molecules tetraphenylethylene (TPE) labeled and caffeic acid (CA) modified fucoidan (FUC) amphiphilic carrier material (CA-FUC-TK-TPE, CFTT) was fabricated, in which the thioketal bond(TK) was used as the linkage arm between TPE and fucoidan chain, giving the CFTT material ROS sensitivity. In addition, amphiphilic carrier material (FUC-TK-VE, FTVE) composed of thioketal-linked vitamin E and fucoidan was synthesized. The mixed carrier material CFTT and FTVE self-assembled in water to form nanoparticles (CFTT - FTVE@PTX-Fe³⁺) loaded with PTX and Fe³⁺. The CDT effect was combined with the chemotherapeutic drug PTX to achieve tumor inhibition. In vitro cell studies have proved that CT/PTX nanoparticles have excellent cell permeability and tumor cytotoxicity. In vivo antitumor experiments confirmed effective antitumor activity and reduced side effects.

Fucoidan and Alginate from the Brown Algae Colpomenia sinuosa and Their Combination with Vitamin C Trigger Apoptosis in Colon Cancer

Brown seaweeds are producers of bioactive molecules which are known to inhibit oncogenic growth. Here, we investigated the antioxidant, cytotoxic, and apoptotic effects of two polysaccharides from the brown algae Colpomenia sinuosa, namely fucoidan and alginate, in a panel of cancer cell lines and evaluated their effects when combined with vitamin C. Fucoidan and alginate were isolated from brown algae and characterized by HPLC, FTIR, and NMR spectroscopy. The results indicated that highly sulfated fucoidans had higher antioxidant and cytotoxic effects than alginate. Human colon cancer cells were the most sensitive to the algal treatments, with fucoidan having an IC50 value (618.9 µg/mL-1) lower than that of alginate (690 µg/mL-1). The production of reactive oxygen species was increased upon treatment of HCT-116 cells with fucoidan and alginate, which suggest that these compounds may trigger cell death via oxidative damage. The combination of fucoidan with vitamin C showed enhanced effects compared to treatment with fucoidan alone, as evidenced by the significant inhibitory effects on HCT-116 colon cancer cell viability. The combination of the algal polysaccharides with vitamin C caused enhanced degeneration in the nuclei of cells, as evidenced by DAPI staining and increased the subG1 population, suggesting the induction of cell death. Together, these results suggest that fucoidan and alginate from the brown algae C. sinuosa are promising anticancer compounds, particularly when used in combination with vitamin C.

Physicochemical properties of fucoidan and its applications as building blocks of nutraceutical delivery systems

Many bioactive ingredients with health effects such as antioxidant, anti-inflammatory and neuroprotective possess low bioavailability due to poor solubility and sensitivity. Fucoidan is an ideal material for encapsulating bioactive ingredients because of its unique physicochemical and biological properties, which can improve the function and application of bioactive ingredients. Nevertheless, there is still a lack of review about the physicochemical properties as well as functionalities of fucoidan and the application of fucoidan-based delivery systems in functional food. Hence, in this review, recent advances on the structure, chemical modification, physicochemical properties and biological activity of fucoidan are summarized. This review systematacially describes the recent update on the fucoidan as a wall material for delivering nutraceuticals with a broad discussion on various types of delivery systems ranging from nanoparticles, nanoparticle/bead complexes, emulsions, edible films, nanocapsules and hydrogels. Futhermore, the technical scientific issues of the application of fucoidan in the field of food are emphasized. On the basis of more comprehensive and deeper understandings, the review ends with a concluding remark on future directions of fucoidan-based delivery systems for purposes. Novel fucoidan-based delivery systems such as aerogels, Pickering emulsions, emulsion-filled-hydrogels, liposomes-in-fucoidan, co-delivery systems of bioactive igredients can be designed.

Fucoidan Independently Enhances Activity in Human Immune Cells and Has a Cytostatic Effect on Prostate Cancer Cells in the Presence of Nivolumab

Fucoidan compounds may increase immune activity and are known to have cancer inhibitory effects in vitro and in vivo. In this study, we aimed to investigate the effect of fucoidan compounds on ex vivo human peripheral blood mononuclear cells (PBMCs), and to determine their cancer cell killing activity both solely, and in combination with an immune-checkpoint inhibitor drug, Nivolumab. Proliferation of PBMCs and interferon gamma (IFNγ) release were assessed in the presence of fucoidan compounds extracted from Fucus vesiculosus, Undaria pinnatifida and Macrocystis pyrifera. Total cell numbers and cell killing activity were assessed using a hormone resistant prostate cancer cell line, PC3. All fucoidan compounds activated PBMCs, and increased the effects of Nivolumab. All fucoidan compounds had significant direct cytostatic effects on PC3 cells, reducing cancer cell numbers, and PBMCs exhibited cell killing activity as measured by apoptosis. However, there was no fucoidan mediated increase in the cell killing activity. In conclusion, fucoidan compounds promoted proliferation and activity of PBMCs and added to the effects of Nivolumab. Fucoidan compounds all had a direct cytostatic effect on PC3 cells, as shown through their proliferation reduction, while their killing was not increased.

Structural diversity of fucoidans and their radioprotective effect

Fucoidans are biologically active sulfated polysaccharides of brown algae. They have a great structural diversity and a wide spectrum of biological activity. This review is intended to outline what is currently known about the structures of fucoidans and their radioprotective effect. We classified fucoidans according to their composition and structure, examined the structure of fucoidans of individual representatives of algae, summarized the available data on changes in the yields and compositions of fucoidans during algae development, and focused on information about underexplored radioprotective effect of these polysaccharides. Based on the presented in the review data, it is possible to select algae, which are the sources of fucoidans of desired structures and to determine the best time to harvest them. The use of high purified polysaccharides with established structures increase the value of studies of their biological effects and the determination of the dependence "structure - biological effect".

Fucoidan-Based Nanoparticles with Inherently Therapeutic Efficacy for Cancer Treatment

The anticancer properties of fucoidan have been widely studied in cancer research. However, the lack of safety information on the parenteral administration of fucoidan and its rapid clearance from the system have limited its application. Herein, we assessed the therapeutic efficacy and safety of fucoidan and developed fucoidan nanoparticles (FuNPs) to enhance their therapeutic effect in the mouse model of breast cancer. FuNPs were synthesized through the emulsion method, and the stable colloid has an average size of 216.3 nm. FuNPs were efficiently internalized into breast cancer cells in vitro, demonstrating an enhanced antitumor activity in comparison with free form fucoidan. After the treatment of FuNPs, the tumor progression was significantly inhibited in viv. The tumor volume was reduced by 2.49-fold compared with the control group. Moreover, the inhibition of the invasion of tumor cells into the lungs revealed the antimetastatic properties of the FuNPs. FuNPs, as naturally marine polysaccharide-based nanoparticles, have shown their broader therapeutic window and enhanced antimetastatic ability, opening an avenue to the development of the inherently therapeutic nanomedicines.

Fucoidan for cardiovascular application and the factors mediating its activities

Fucoidan is a sulfated polysaccharide with various bioactivities. The application of fucoidan in cancer treatment, wound healing, and food industry has been extensively studied. However, the therapeutic value of fucoidan in cardiovascular diseases has been less explored. Increasing number of investigations in the past years have demonstrated the effects of fucoidan on cardiovascular system. In this review, we will focus on the bioactivities related to cardiovascular applications, for example, the modulation functions of fucoidan on coagulation system, inflammation, and vascular cells. Factors mediating those activities will be discussed in detail. Current therapeutic strategies and future opportunities and challenges will be provided to inspire and guide further research.

Fucoidan as an Autophagy Regulator: Mechanisms and Therapeutic Potentials for Cancer and Other Diseases

Fucoidan, a natural polysaccharide with a variety of classical bioactivities mainly sourced from brown algae, has been extensively studied owing to its favorable pharmacological effects, including anti-inflammatory, anti-tumor, anticoagulant and liver protection. Recently it has been found to play a regulatory role in the processes of autophagy. Autophagy is an important cellular process that effectively protects cells and organisms from stimulating factors such as nutrient deficiency, low cellular ATP levels, metabolic stress, growth factor deprivation and hypoxic conditions. In recent years, many studies have shown that fucoidan can treat human diseases by regulating autophagy process though cell signaling pathways. In this review, we summarize the latest progress in the discovery of natural autophagy regulator of fucoidan for the therapeutic application in cardiac diseases, cancers and liver diseases, aiming to provide the new pharmacological application that fucoidan may treat human diseases by regulating autophagy. Furthermore, we look forward to seeing more diseases that would be treated by autophagy modulator of fucoidan and the discovery of more elaborate autophagy regulation mechanism.