Fucoidan extracted from Cladosiphon okamuranus Tokida induces apoptosis of human T-cell leukemia virus type 1-infected T-cell lines and primary adult T-cell leukemia cells

A Fucose-Containing Sulfated Polysaccharide from Spatoglossum schröederi Potentially Targets Tumor Growth Rather Than Cytotoxicity: Distinguishing Action on Human Melanoma Cell Lines

Natural substances are strategic candidates for drug development in cancer research. Marine-derived molecules are of special interest due to their wide range of biological activities and sustainable large-scale production. Melanoma is a type of skin cancer that originates from genetic mutations in melanocytes. BRAF, RAS, and NF1 mutations are described as the major melanoma drivers, but approximately 20% of patients lack these mutations and are included in the triple wild-type (tripleWT) classification. Recent advances in targeted therapy directed at driver mutations along with immunotherapy have only partially improved patients' overall survival, and consequently, melanoma remains deadly when in advanced stages. Fucose-containing sulfated polysaccharides (FCSP) are potential candidates to treat melanoma; therefore, we investigated Fucan A, a FCSP from Spatoglossum schröederi brown seaweed, in vitro in human melanoma cell lines presenting different mutations. Up to 72 h Fucan A treatment was not cytotoxic either to normal melanocytes or melanoma cell lines. Interestingly, it was able to impair the tripleWT CHL-1 cell proliferation (57%), comparable to the chemotherapeutic cytotoxic drug cisplatin results, with the advantage of not causing cytotoxicity. Fucan A increased CHL-1 doubling time, an effect attributed to cell cycle arrest. Vascular mimicry, a close related angiogenesis process, was also impaired (73%). Fucan A mode of action could be related to gene expression modulation, in special β-catenin downregulation, a molecule with protagonist roles in important signaling pathways. Taken together, results indicate that Fucan A is a potential anticancer molecule and, therefore, deserves further investigation.

Fucoidan's Molecular Targets: A Comprehensive Review of Its Unique and Multiple Targets Accounting for Promising Bioactivities Supported by In Silico Studies

Fucoidan is a class of multifunctional polysaccharides derived from marine organisms. Its unique and diversified physicochemical and chemical properties have qualified them for potential and promising pharmacological uses in human diseases, including inflammation, tumors, immunity disorders, kidney diseases, and diabetes. Physicochemical and chemical properties are the main contributors to these bioactivities. The previous literature has attributed such activities to its ability to target key enzymes and receptors involved in potential disease pathways, either directly or indirectly, where the anionic sulfate ester groups are mainly involved in these interactions. These findings also confirm the advantageous pharmacological uses of sulfated versus non-sulfated polysaccharides. The current review shall highlight the molecular targets of fucoidans, especially enzymes, and the subsequent responses via either the upregulation or downregulation of mediators' expression in various tissue abnormalities. In addition, in silico studies will be applied to support the previous findings and show the significant contributors. The current review may help in understanding the molecular mechanisms of fucoidan. Also, the findings of this review may be utilized in the design of specific oligomers inspired by fucoidan with the purpose of treating life-threatening human diseases effectively.

Rehashing Our Insight of Seaweeds as a Potential Source of Foods, Nutraceuticals, and Pharmaceuticals

In a few Southeast Asian nations, seaweeds have been a staple of the cuisine since prehistoric times. Seaweeds are currently becoming more and more popular around the world due to their superior nutritional value and medicinal properties. This is because of rising seaweed production on a global scale and substantial research on their composition and bioactivities over the past 20 years. By reviewing several articles in the literature, this review aimed to provide comprehensive information about the primary and secondary metabolites and various classes of bioactive compounds, such as polysaccharides, polyphenols, proteins, and essential fatty acids, along with their bioactivities, in a single article. This review also highlights the potential of seaweeds in the development of nutraceuticals, with a particular focus on their ability to enhance human health and overall well-being. In addition, we discuss the challenges and potential opportunities associated with the advancement of pharmaceuticals and nutraceuticals derived from seaweeds, as well as their incorporation into different industrial sectors. Furthermore, we find that many bioactive constituents found in seaweeds have demonstrated potential in terms of different therapeutic attributes, including antioxidative, anti-inflammatory, anticancer, and other properties. In conclusion, seaweed-based bioactive compounds have a huge potential to play an important role in the food, nutraceutical, and pharmaceutical sectors. However, future research should pay more attention to developing efficient techniques for the extraction and purification of compounds as well as their toxicity analysis, clinical efficacy, mode of action, and interactions with regular diets.

Mouse Models for HTLV-1 Infection and Adult T Cell Leukemia

Adult T cell leukemia (ATL) is an aggressive hematologic disease caused by human T cell leukemia virus type 1 (HTLV-1) infection. Various animal models of HTLV-1 infection/ATL have been established to elucidate the pathogenesis of ATL and develop appropriate treatments. For analyses employing murine models, transgenic and immunodeficient mice are used because of the low infectivity of HTLV-1 in mice. Each mouse model has different characteristics that must be considered before use for different HTLV-1 research purposes. HTLV-1 Tax and HBZ transgenic mice spontaneously develop tumors, and the roles of both Tax and HBZ in cell transformation and tumor growth have been established. Severely immunodeficient mice were able to be engrafted with ATL cell lines and have been used in preclinical studies of candidate molecules for the treatment of ATL. HTLV-1-infected humanized mice with an established human immune system are a suitable model to characterize cells in the early stages of HTLV-1 infection. This review outlines the characteristics of mouse models of HTLV-1 infection/ATL and describes progress made in elucidating the pathogenesis of ATL and developing related therapies using these mice.

Seaweeds in the Oncology Arena: Anti-Cancer Potential of Fucoidan as a Drug—A Review

Marine natural products are a discerning arena to search for the future generation of medications to treat a spectrum of ailments. Meanwhile, cancer is becoming more ubiquitous over the world, and the likelihood of dying from it is rising. Surgery, radiation, and chemotherapy are the mainstays of cancer treatment worldwide, but their extensive side effects limit their curative effect. The quest for low-toxicity marine drugs to prevent and treat cancer is one of the current research priorities of researchers. Fucoidan, an algal sulfated polysaccharide, is a potent therapeutic lead candidate against cancer, signifying that far more research is needed. Fucoidan is a versatile, nontoxic marine-origin heteropolysaccharide that has received much attention due to its beneficial biological properties and safety. Fucoidan has been demonstrated to exhibit a variety of conventional bioactivities, such as antiviral, antioxidant, and immune-modulatory characteristics, and anticancer activity against a wide range of malignancies has also recently been discovered. Fucoidan inhibits tumorigenesis by prompting cell cycle arrest and apoptosis, blocking metastasis and angiogenesis, and modulating physiological signaling molecules. This review compiles the molecular and cellular aspects, immunomodulatory and anticancer actions of fucoidan as a natural marine anticancer agent. Specific fucoidan and membranaceous polysaccharides from Ecklonia cava, Laminaria japonica, Fucus vesiculosus, Astragalus, Ascophyllum nodosum, Codium fragile serving as potential anticancer marine drugs are discussed in this review.

Characteristics of Marine Biomaterials and Their Applications in Biomedicine

Oceans have vast potential to develop high-value bioactive substances and biomaterials. In the past decades, many biomaterials have come from marine organisms, but due to the wide variety of organisms living in the oceans, the great diversity of marine-derived materials remains explored. The marine biomaterials that have been found and studied have excellent biological activity, unique chemical structure, good biocompatibility, low toxicity, and suitable degradation, and can be used as attractive tissue material engineering and regenerative medicine applications. In this review, we give an overview of the extraction and processing methods and chemical and biological characteristics of common marine polysaccharides and proteins. This review also briefly explains their important applications in anticancer, antiviral, drug delivery, tissue engineering, and other fields.

Brown Algae Carbohydrates: Structures, Pharmaceutical Properties, and Research Challenges

Brown algae (Phaeophyceae) have been consumed by humans for hundreds of years. Current studies have shown that brown algae are rich sources of bioactive compounds with excellent nutritional value, and are considered functional foods with health benefits. Polysaccharides are the main constituents of brown algae; their diverse structures allow many unique physical and chemical properties that help to moderate a wide range of biological activities, including immunomodulation, antibacterial, antioxidant, prebiotic, antihypertensive, antidiabetic, antitumor, and anticoagulant activities. In this review, we focus on the major polysaccharide components in brown algae: the alginate, laminarin, and fucoidan. We explore how their structure leads to their health benefits, and their application prospects in functional foods and pharmaceuticals. Finally, we summarize the latest developments in applied research on brown algae polysaccharides.

Effects of Ingesting Fucoidan Derived from Cladosiphon okamuranus Tokida on Human NK Cells: A Randomized, Double-Blind, Parallel-Group, Placebo-Controlled Pilot Study

The aim of this study was to evaluate the effects of ingesting fucoidan derived from Okinawa mozuku (Cladosiphon okamuranus) on natural killer (NK) cell activity and to assess its safety in healthy adults via a randomized, double-blind, parallel-group, placebo-controlled pilot study. Subjects were randomly divided into two groups-a placebo group (ingesting citric acid, sucralose, and caramel beverages; n = 20; 45.5 ± 7.8 years (mean ± standard deviation)) and a fucoidan group (3.0 g/day from beverages; n = 20; 47.0 ± 7.6 years); after 12 weeks, blood, biochemical, and immunological tests were performed. Clinically adverse events were not observed in any of the tests during the study period. In addition, adverse events due to the test food were not observed. In the immunological tests, NK cell activity was significantly enhanced at 8 weeks in the fucoidan group, compared to before ingestion (0 weeks). In addition, a significantly enhanced NK cell activity was observed in male subjects at 8 weeks, compared with the placebo group. These results confirm that Okinawa mozuku-derived fucoidan enhances NK cell activity and suggest that it is a safe food material.

Intestinal Microbiota and Immune Modulation in Zebrafish by Fucoidan From Okinawa Mozuku (Cladosiphon okamuranus)

Fucoidan represents fucose-rich sulfated polysaccharides derived from brown seaweeds, which exerts various biological activities applicable for functional foods and therapeutic agents. The objective of the present study was to investigate in vivo effects of fucoidan extracted from Okinawa mozuku (Cladosiphon okamuranus), common edible seaweed in Japan, on immune responses and microbiota composition in zebrafish. We treated larvae and adult zebrafish with Okinawa mozuku (OM) fucoidan by immersion (100 and 500 μg/mL, 3 days) and by feeding (3 weeks), respectively. The effect of OM fucoidan on immune responses in zebrafish larvae was evaluated by live imaging of neutrophils and macrophages as well as quantitative polymerase chain reaction of pro- and anti-inflammatory cytokine genes. Whole microbiota of zebrafish larvae and intestinal microbiota of adult zebrafish treated with OM fucoidan were analyzed by Illumina MiSeq pair-end sequencing of the V3–V4 region of 16S rRNA genes. Fucoidan treatment only slightly affected the composition of the larvae microbiota and the number of neutrophils and macrophages, while pro- and anti-inflammatory cytokine gene expression levels were upregulated in the larvae treated with 500 μg/mL OM fucoidan. In contrast, feeding of OM fucoidan clearly altered the intestinal microbiota composition of adult zebrafish, which was characterized by the emergence and predominance of multiple bacterial operational taxonomic units (OTUs) affiliated with Rhizobiaceae and Comamonadaceae at the expense of E. coli-related Enterobacteriaceae, the dominant OTUs throughout the studied samples. These changes were accompanied by decreased expression levels of pro-inflammatory cytokine il1b in the intestines of the adult zebrafish. Our current study provides the first insights into in vivo modulatory effects of fucoidan on microbiota and immune responses of unchallenged zebrafish, which underscores the potential of fucoidan to play a modulatory role in the diet–microbiota–host interplay.

Bioactive compounds in seaweeds: An overview of their biological properties and safety

Seaweeds are among the significant currently exploited marine plant resources which are gaining full applications in culinary, cosmetic, pharmaceutical, and biotechnological processes. Much attention has been devoted to seaweeds based on their proven health benefits and is considered as a rich source of structurally different bioactive metabolites for the discovery of novel functional food-based pharmacophores/drugs. Nonetheless, there is still a dearth of updated compilation and analysis of the in-depth pharmacological activities of these compounds. This review, therefore, aims to provide a piece of up-to-date detailed information on the major compounds isolated from various seaweed species together with their in-vitro and in-vivo biological properties. These compounds were found to possess broad pharmacological properties and inhibitory enzyme activities against critical enzymes involved in the aetiology of noncommunicable diseases. However, their toxicity, clinical efficacy, mechanisms of action, and interaction with conventional foods, are still less explored and require more attention in future studies.

Evaluation of the Immunomodulatory Effects of Fucoidan Derived from Cladosiphon Okamuranus Tokida in Mice

Okinawa mozuku (Cladosiphon okamuranus Tokida) is an edible seaweed classified as brown algae and is a native species of the Ryukyu Islands in Japan. In recent years, the genomic decoding of Okinawa mozuku has been completed. Previous studies on the anti-inflammatory, antiviral, and antitumor properties of Okinawa mozuku have suggested that it affects the regulation of cellular and humoral immunity. The aim of the present study was to examine the immunoregulatory effect of fucoidan derived from Okinawa mozuku in mice. A product containing fucoidan (purity, 88.3%; molecular weight, 49.8 kDa) was developed from Okinawa mozuku and tested for its immunoregulatory effects in mice. The experimental animals were 8-week-old female BALB/c mice to which fucoidan (0, 102.5, 205.0, 410.0, and 1025.0 mg/kg) was administered orally continuously for six weeks. Immune cell proliferation, cytokine production, macrophage phagocytosis, and serum antibody concentration were measured. We found that immune cell proliferation, interleukin (IL)-2, macrophage phagocytes, and serum antibodies (IgM, -G, -A) increased significantly, but IL-4, -5, and IgE decreased significantly. These results indicated that fucoidan modulated cellular and humoral immunity.

Molecular Mechanisms Underlying Cancer Preventive and Therapeutic Potential of Algal Polysaccharides

Background:

Algal polysaccharide and oligosaccharide derivatives have been shown to possess a variety of therapeutic potentials and drug delivery applications. Algal polysaccharides contain sulfated sugar monomers derived from seaweed including brown, red, and green microalgae. Here, in this review, the recent progress of algal polysaccharides’ therapeutic applications as anticancer agents, as well as underlying cellular and molecular mechanisms was investigated. Moreover, recent progress in the structural chemistry of important polysaccharides with anticancer activities were illustrated.

Methods:

Electronic databases including “Scopus”, “PubMed”, and “Cochrane library” were searched using the keywords “cancer”, or “tumor”, or “malignancy” in title/abstract, along with “algae”, or “algal” in the whole text until July 2018. Only English language papers were included.

Results:

The most common polysaccharides involved in cancer management were sulfated polysaccharides, Fucoidans, Carageenans, and Ulvan from different species of algae that have been recognized in vitro and in vivo. The underlying anticancer mechanisms of algal polysaccharides included induction of apoptosis, cell cycle arrest, modulation of transduction signaling pathways, suppression of migration and angiogenesis, as well as activation of immune responses and antioxidant system. VEGF/VEGFR2, TGFR/Smad/Snail, TLR4/ROS/ER, CXCL12/ CXCR4, TGFR/Smad7/Smurf2, PI3K/AKT/mTOR, PBK/TOPK, and β-catenin/Wnt are among the main cellular signaling pathways which have a key role in the preventive and therapeutic effects of algal polysaccharides against oncogenesis.

Conclusion:

Algal polysaccharides play a crucial role in the management of cancer and may be considered the next frontier in pharmaceutical research. Further well-designed clinical trials are mandatory to evaluate the efficacy and safety of algal polysaccharides in patients with cancer.

Fucoidan Promotes Apoptosis and Inhibits EMT of Breast Cancer Cells

Fucoidan is an active component of seaweed, and could inhibit proliferation and induce apoptotic cell death in several tumor cells. However, the function of fucoidan in breast cancer is largely unknown. In the present study, we evaluated the anti-cancer potential of fucoidan in human breast cancer MCF-7 cells. Adult Sprague-Dawley rats were randomized to receive fucoidan (200 or 400 mg/kg·body weight per day) or normal saline via gastric gavage for 3 consecutive days. Serum samples were prepared from these rats, and used for subsequent experiments to examine the potential effects in MCF-7 cells. Cell viability was determined using a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Apoptosis was examined with Hoechst33258 staining and flow cytometry. Cell migration and invasion were measured by wound scratch assay and Transwell assay, respectively. Western blot and enzyme-linked immunosorbent assay (ELISA) were used to examine the expression of secretory E-cadherin and matrix metalloproteinase-9 (MMP-9). Conditioned serum from fucoidan-treated rats significantly suppressed cell proliferation and enhanced apoptosis. Cell migration and invasion were also significantly decreased. Observed effects of conditioned serum were associated with upregulation of E-cadherin and downregulation of MMP-9. Conditioned serum of rats treated with fucoidan could inhibit the proliferation and promote apoptosis of MCF-7 cells. Cell invasion and migration were inhibited, possibly via decreased epithelial-mesenchymal transition (EMT) process. Fucoidan may be a promising therapeutic agent for human breast cancers.

Biological Activities of Fucoidan and the Factors Mediating Its Therapeutic Effects: A Review of Recent Studies

The marine acid polysaccharide fucoidan has attracted attention from both the food and pharmaceutical industries due to its promising therapeutic effects. Fucoidan is a polysaccharide that mainly consists of L-fucose and sulphate groups. Its excellent biological function is attributed to its unique biological structure. Classical activities include antitumor, antioxidant, anticoagulant, antithrombotic, immunoregulatory, antiviral and anti-inflammatory effects. More recently, fucoidan has been shown to alleviate metabolic syndrome, protect the gastrointestinal tract, benefit angiogenesis and bone health. This review focuses on the progress in our understanding of the biological activities of fucoidan, highlighting its benefits for the treatment of human disease. We hope that this review can provide some theoretical basis and inspiration for the product development of fucoidan.

New Drugs from the Sea: Pro-Apoptotic Activity of Sponges and Algae Derived Compounds

Natural compounds derived from marine organisms exhibit a wide variety of biological activities. Over the last decades, a great interest has been focused on the anti-tumour role of sponges and algae that constitute the major source of these bioactive metabolites. A substantial number of chemically different structures from different species have demonstrated inhibition of tumour growth and progression by inducing apoptosis in several types of human cancer. The molecular mechanisms by which marine natural products activate apoptosis mainly include (1) a dysregulation of the mitochondrial pathway; (2) the activation of caspases; and/or (3) increase of death signals through transmembrane death receptors. This great variety of mechanisms of action may help to overcome the multitude of resistances exhibited by different tumour specimens. Therefore, products from marine organisms and their synthetic derivates might represent promising sources for new anticancer drugs, both as single agents or as co-adjuvants with other chemotherapeutics. This review will focus on some selected bioactive molecules from sponges and algae with pro-apoptotic potential in tumour cells.

Fucoidan Structure and Activity in Relation to Anti-Cancer Mechanisms

Fucoidan is a natural derived compound found in different species of brown algae and in some animals, that has gained attention for its anticancer properties. However, the exact mechanism of action is currently unknown. Therefore, this review will address fucoidans structure, the bioavailability, and all known different pathways affected by fucoidan, in order to formulate fucoidans structure and activity in relation to its anti-cancer mechanisms. The general bioactivity of fucoidan is difficult to establish due to factors like species-related structural diversity, growth conditions, and the extraction method. The main pathways influenced by fucoidan are the PI3K/AKT, the MAPK pathway, and the caspase pathway. PTEN seems to be important in the fucoidan-mediated effect on the AKT pathway. Furthermore, the interaction with VEGF, BMP, TGF-β, and estrogen receptors are discussed. Also, fucoidan as an adjunct seems to have beneficial effects, for both the enhanced effectiveness of chemotherapy and reduced toxicity in healthy cells. In conclusion, the multipotent character of fucoidan is promising in future anti-cancer treatment. However, there is a need for more specified studies of the structure⁻activity relationship of fucoidan from the most promising seaweed species.

Investigation of Different Molecular Weight Fucoidan Fractions Derived from New Zealand Undaria pinnatifida in Combination with GroA Therapy in Prostate Cancer Cell Lines

Fucoidan, a sulfated polysaccharide extracted from brown seaweeds, has been shown to possess various antioxidant, anticoagulant, antiviral, and anticancer functions. In this study, we focused on low molecular weight fucoidan (LMWF) which was extracted from New Zealand Undaria pinnatifida, and investigated its anti-proliferative effects, combined with a quadruplex-forming oligonucleotide aptamer (GroA, AS1411), a powerful cell surface Nucleolin inhibitor, in prostate cancer cells. We examined LMWF (<10 kDa) and compared it with laboratory grade Fucoidan purchased from Sigma (FS), all extracted from the same seaweed species U. pinnatifida. We found that LMWF significantly improved the anti-proliferative effect of GroA, as it decreased cancer cell growth and viability and increased cell death. This research may provide the foundation for LMWF to be used against prostate cancers as a supplement therapy in combination with other therapeutic agents.

Metabolites Unravel Nutraceutical Potential of Edible Seaweeds: An Emerging Source of Functional Food

Functional foods are nutritional compounds which also provide health and medicinal benefits. Daily food intake has much impact on the quality of life, and therefore inclusion of functional foods is now essential to our diet. Nutraceuticals are neither food nor drug but are added to food to provide extra nutritional and physiological properties. Though nutraceutical compounds provide minimal actions, their regular involvement in the diet can provide major and long-term health benefits. Global demand for additional and sustainable biomass for the production of important metabolites with nutraceutical potential has resulted in renewed interest in seaweeds. Seaweeds have been consumed from ancient times in Asian areas, and in recent times they have been demonstrated to possess many medicinal effects. Seaweeds are considered a rich source of various nutritional ingredients and metabolites that have pharmaceutical properties. It has been observed that total protein, from terrestrial plants such as soybean and wheat, produces an allergic response on consumption. Therefore, seaweed proteins can be considered a promising source for food industries. Overall, seaweeds are a rich source of PUFAs, metabolites, proteins, sulfated polysaccharides, vitamins, and minerals, which are all responsible for different bioactivities; they are therefore considered a promising functional food (nutraceutical). In this review we discuss the nutraceutical potential of seaweeds regarding different metabolites (primary and secondary), variation in composition, probable biological applications, limitations, research gaps, and future prospects.

Investigation of antioxidant and anticancer potential of fucoidan from Sargassum polycystum

The present study was aimed to evaluate the antioxidant and anticancer potential of fucoidan isolated from Sargassum polycystum. The isolated fucoidan was successfully purified by DEAE cellulose-ion exchange chromatography and dialysis. Totally four active fractions (F1-F4) were collected and explored its chemical constitution by calorimetric assays. Among them, fraction 2 (F2) showed the higher yield percentage, fucose and sulphate content. Further, monosaccharide composition, structural and functional properties of the F2 was analyzed by HPLC, FTIR and NMR. F2 shows highest DPPH radical scavenging activity (55.94 ± 0.69%), reducing power (0.33 absorbance rate), hydrogen peroxide scavenging activity (71.76 ± 2.14%) and nitric oxide radical scavenging activity (51.81 ± 1.04%) at 1000 μg/ml. The cell viability of MCF-7 and HCT-15 cell lines was proportionate to the concentration of F2 with an estimated IC50 was 20 and 50 μg/ml respectively. The fluorescence and confocal laser scanning microscopic analysis demonstrated the apoptotic morphological changes and cell mediated death in F2 treated cancer cells. Higher amount of LDH release was found in the F2 treated cancer cells than the control group. Thus, the present finding proved that the isolated F2 encompasses significant antioxidant and anticancer property.

Mitotic kinase PBK/TOPK as a therapeutic target for adult T‑cell leukemia/lymphoma

Adult T‑cell leukemia/lymphoma (ATLL) is a disorder involving human T-cell leukemia virus type 1 (HTLV‑1)-infected T‑cells characterized by increased clonal neoplastic proliferation. PDZ-binding kinase (PBK) [also known as T‑lymphokine-activated killer cell-originated protein kinase (TOPK)] is a serine/threonine kinase expressed in proliferative cells and is phosphorylated during mitosis. In this study, the expression and phosphorylation of PBK/TOPK were examined by western blot analysis and RT‑PCR. We found that PBK/TOPK was upregulated and phosphorylated in HTLV‑1-transformed T‑cell lines and ATLL‑derived T‑cell lines. Notably, CDK1/cyclin B1, which phosphorylates PBK/TOPK, was overexpressed in these cells. HTLV‑1 infection upregulated PBK/TOPK expression in peripheral blood mononuclear cells (PBMCs) in co-culture assays. The potent PBK/TOPK inhibitors, HI‑TOPK‑032, and fucoidan from brown algae, decreased the proliferation and viability of these cell lines in a dose‑dependent manner. By contrast, the effect of HI‑TOPK‑032 on PBMCs was less pronounced. Treatment with HI‑TOPK‑032 resulted in G1 cell cycle arrest, and decreased CDK6 expression and pRb phosphorylation, which are critical determinants of progression through the G1 phase. In addition, HI‑TOPK‑032 induced apoptosis, as evidenced by morphological changes, the cleavage of poly(ADP-ribose) polymerase with the activation of caspase‑3, -8 and -9, and an increase in the sub‑G1 cell population and APO2.7-positive cells. Moreover, HI‑TOPK‑032 inhibited the expression of cellular inhibitor of apoptosis 2 (c-IAP2), X-linked inhibitor of apoptosis protein (XIAP), survivin and myeloid cell leukemia‑1 (Mcl‑1), and induced the expression of Bak and interferon-induced protein with tetratricopeptide repeats (IFIT)1, 2 and 3. It is noteworthy that the use of this inhibitor led to the inhibition of the phosphorylation of IκB kinase (IKK)α, IKKβ, IκBα, phosphatase and tensin homolog (PTEN) and Akt, and to the decreased protein expression of JunB and JunD, suggesting that PBK/TOPK affects the nuclear factor-κB, Akt and activator protein‑1 signaling pathways. In vivo, the administration of HI‑TOPK‑032 suppressed tumor growth in an ATLL xenograft model. Thus, on the whole, this study on the identification and functional analysis of PBK/TOPK suggests that this kinase is a promising molecular target for ATLL treatment.

Effect of Fucoidan on Anterior Cruciate Ligament Transection and Medial Meniscectomy Induced Osteoarthritis in High-Fat Diet-Induced Obese Rats

Osteoarthritis (OA) has become one of the most common disabilities among elders, especially in females. Obesity and mechanical injuries caused by OA are attributed to joint loading, cartilage disintegration, and bone loss, as well as inflammation. Pharmacological and non-pharmacological treatments can be used for OA. Fucoidan possesses several bioactivities such as antitumor, antiviral, anticoagulation, anti-obesity, and immunomodulation. This study aims to investigate the effect of fucoidan in surgery-induced OA on rats with diet-induced obesity. OA was induced by an anterior cruciate ligament transection and a partial medial meniscectomy (ACLT + MMx). The male SD rats were fed with a high-fat diet (HFD) for 4 weeks to induce obesity before causing ACLT + MMx to induce OA. The OA rats were administered with intragastric water or fucoidan in three different concentrations (32 mg/kg, 64 mg/kg, and 320 mg/kg) after the surgeries for 40 days with an HFD. We observed that the swelling in the knee joint was alleviated and the hind paw weight distribution was rectified after feeding them with fucoidan and that there was no significant effect on the weight gain and feed intake. Fucoidan administration indicated no significant variation on the high-density lipoprotein (HDL)-Cholesterol level, but it did indicate reduced plasma triglycerides and low-density lipoprotein (LDL)-Cholesterol levels. In addition, the weight-bearing tests showed an improvement in the fucoidan-treated group. Our results suggested that fucoidan may improve meniscal/ligamentous injury and obesity-induced OA.

In vitro and in vivo anti-primary effusion lymphoma activities of fucoidan extracted from Cladosiphon okamuranus Tokida

Primary effusion lymphoma (PEL) caused by Kaposi's sarcoma-associated herpesvirus (KSHV) is characterized by lymphomatous effusion in body cavities and poor prognosis. There is still no effective treatment for PEL. Fucoidan, a major sulfated polysaccharide isolated from brown seaweeds, has an attractive array of bioactivities such as cancer inhibition. However, the effects of fucoidan on PEL cells remain unclear. We investigated the anti-PEL effects of fucoidan obtained from Cladosiphon okamuranus Tokida cultivated in Okinawa. Fucoidan dose-dependently inhibited the proliferation of KSHV-infected PEL cell lines, and provoked G1 cell cycle arrest, which was accompanied by CDK4 and CDK6 downregulation. Fucoidan also induced apoptosis of PEL cells through caspase-3, -8 and -9 activation; this occurred partly through the downregulation of anti-apoptotic Bcl-xL, Mcl-1 and XIAP proteins. Fucoidan also suppressed nuclear factor-κB, activator protein-1 (AP-1), and T-lymphokine-activated killer cell-originated protein kinase (TOPK) signaling pathways through inhibition of phosphorylation of IκBα and TOPK, and the expression of AP-1 family proteins, JunB and JunD. Oral administration of fucoidan effectively inhibited the development of PEL cells and ascites in a xenograft SCID mouse model, with minimal serious adverse effects. Notably, native fucoidan exhibited a more efficient anti-PEL effect than nanoparticle fucoidan. These preclinical findings highlight the anti-PEL actions of fucoidan, suggesting it could be potentially useful for the prevention and treatment of PEL.

Antibacterial activity and mechanisms of depolymerized fucoidans isolated from Laminaria japonica

Fucoidans, sulfated polysaccharides in brown algae, were depolymerized though high-pressure hydrolysis, and their antibacterial activity, structural properties, and antibacterial mechanisms were investigated in this work. The fucoidans from Laminaria japonica show no antibacterial activity before depolymerization; however, their depolymerized products can effectively (p<0.05) inhibit the proliferation of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The structure-activity study demonstrated that lower molecular weight and stronger polyanionic property can promote the antibacterial activity. And the depolymerized fucoidans exhibited better antibacterial activity against E. coli than against S. aureus. The results also indicated that the bactericidal pathway of depolymerized fucoidans should be through destruction of the cytomembranes and the target molecules are the membrane proteins, which can result in changed membrane fluidity and/or activated autophagocytosis. Therefore, the depolymerized fucoidans possess potential appliance values in partly or totally replacing antibiotics in our daily life.

Isolation of fucoidan from Sargassum polycystum brown algae: Structural characterization, in vitro antioxidant and anticancer activity

In this study antioxidant and anticancer effect of fucoidan isolated from brown seaweed Sargassum polycystum was investigated. The total yield of fucoidan was 4.51±0.24%, of these, 46.8% of fucose and 22.35±0.23% of sulphate respectively. The structural characteristic of fucoidan was analyzed by Fourier transform infrared spectroscopy and nuclear magnetic resonance. The antioxidant properties were determined by DPPH scavenging, reducing power and total antioxidant assays. The maximum DPPH scavenging activity (61.2±0.33%), reducing ability (67.56±0.26%) and total antioxidant activity (65.3±0.66%) were obtained at 1000μg/ml of fucoidan. The cytotoxicity effect of fucoidan showed a higher percentage (90.4±0.25%) of inhibition against the MCF-7 cell line at 150μg/ml with an estimated IC50 at 50μg/ml. Further, cytomorphological and apoptosis changes of fucoidan treated cells were observed under inverted light microscope and confocal laser scanning microscope (CLSM). The results demonstrated that the isolated fucoidan from S. polycystum possessed potent antioxidant and anticancer properties.

Induction of p53-Independent Apoptosis and G1 Cell Cycle Arrest by Fucoidan in HCT116 Human Colorectal Carcinoma Cells

It is well known that fucoidan, a natural sulfated polysaccharide present in various brown algae, mediates anticancer effects through the induction of cell cycle arrest and apoptosis. Nevertheless, the role of tumor suppressor p53 in the mechanism action of fucoidan remains unclear. Here, we investigated the anticancer effect of fucoidan on two p53 isogenic HCT116 (p53+/+ and p53-/-) cell lines. Our results showed that inhibition of cell viability, induction of apoptosis and DNA damage by treatment with fucoidan were similar in two cell lines. Flow cytometric analysis revealed that fucoidan resulted in G1 arrest in the cell cycle progression, which correlated with the inhibition of phosphorylation of retinoblastoma protein (pRB) and concomitant association of pRB with the transcription factor E2Fs. Furthermore, treatment with fucoidan obviously upregulated the expression of cyclin-dependent kinase (CDK) inhibitors, such as p21WAF1/CIP1 and p27KIP1, which was paralleled by an enhanced binding with CDK2 and CDK4. These events also commonly occurred in both cell lines, suggesting that fucoidan triggered G1 arrest and apoptosis in HCT116 cells by a p53-independent mechanism. Thus, given that most tumors exhibit functional p53 inactivation, fucoidan could be a possible therapeutic option for cancer treatment regardless of the p53 status.

Sargassum fusiforme polysaccharides inhibit VEGF-A-related angiogenesis and proliferation of lung cancer in vitro and in vivo

Sargassum fusiforme (Harv.) is a brown alga belonging to the Sargasaceae family. The Sargassum fusiforme polysaccharides (SFPS) have demonstrated good anti-tumor and immunomodulatory activity. However, the underlying mechanisms of its anti-tumorigenesis, especially the anti-angiogenic activity is yet to be established. In the present study, we attempted to determine the effects of SFPS on the human lung adenocarcinoma SPC-A-1 cells and its xenograft model. The results showed that SFPS provides a concentration-dependent inhibition of SPC-A-1 cell proliferation in in vitro and the tumor growth in in vivo studies. Immunohistochemistry studies revealed that the administration of SFPS significantly decreased CD31, VEGF-A expression and the tumor microvessel density (MVD). SFPS also provided a dose-dependent impairment of cell vitality, induction of cell cycle arrest and apoptosis of human umbilical vein endothelial cells (HUVECs). SFPS inhibited the expression of VEGF-A in tumor cells and its receptor VEGFR2 in HUVECs. The HUVEC tube formation assay showed that SFPS could abrogate the tube formation with relatively decreased tubes length of tube-like capillary similar to anti-VEGF antibody, Avastin®. These findings suggested that SFPS could be used as an alternative anticancer drug as they inhibited the angiogenesis and the microvessel formation through disruption of VEGF signals apart from direct tumor cytotoxicity.

Facile size-controlled synthesis of fucoidan-coated gold nanoparticles and cooperative anticancer effect with doxorubicin

Facile one-pot synthesis, surface modification and doxorubicin conjugation of anticancer biopolymer fucoidan coated gold nanoparticle enabled highly efficient cancer therapy through cooperative treatment feasibility.

Innocuity and anti-Newcastle-virus-activity of Cladosiphon okamuranus fucoidan in chicken embryos

This study evaluated the potential toxicity and antiviral activity of fucoidan from Cladosiphon okamuranus against Newcastle disease virus (NDV), one of the most serious threats to the poultry industry in the world. Toxicity was assayed on chicken embryo fibroblast (CEF) secondary cultures at concentrations ranging from 0.1 to 1500 μg per mL culture medium, assessing the cell viability by the yellow tetrazolium MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay, and on 9-day-old embryonated chicken eggs by inoculation of 2 to 500 μg doses in the allantoic cavity, assessing the embryos morphology and liver histology. At 48 h post-inoculation, viability of CEF exposed to concentrations up to 10 μg/mL was not significantly affected, and the 50% cytotoxic concentration was estimated as of 1062 μg/mL; after exposure in ovo, some chick embryos showed liver steatosis when treated with fucoidan doses over 20 μg per egg (15 to 28% at 200 μg, 27 to 56% at 500 μg), but no change was detected in their size or aspect. Antiviral activity was tested by treating 9-day-old embryos via the allantoic route with 0.25 to 16 μg fucoidan doses that were applied at different times (-1, 0 and +1 h) relative to the inoculation of 10,000 folds the 50% Tissue Culture Infective Dose (TCID50) of the NDV, La Sota strain. At 72 h post infection, virus titration in the allantoic fluid by hemagglutination assay (HA) showed a considerable and significant inhibition of infectivity for all doses, the best result (a 90% decrease) being obtained in embryos treated with 1 μg fucoidan one hour before infection. Viral RNA semi-quantification in pooled liver and small intestine of embryos that had been treated with 4 and 16 μg fucoidan 1 h before the infection showed reductions of the virus replication by 60 and 99.8%, respectively. Since this high anti-NDV activity in ovo was obtained with quite innocuous doses, fucoidan from C. okamuranus could be a potential low-toxicity antiviral compound to be used in areas exposed to NDV.

A review about the development of fucoidan in antitumor activity: Progress and challenges

Fucoidan is composed of l-fucose, sulfate groups and one or more small proportions of d-xylose, d-mannose, d-galactose, l-rhamnose, arabinose, glucose, d-glucuronic acid and acetyl groups in different kinds of brown seaweeds. Many reports have demonstrated that fucoidan has antitumor activities on various cancers. However, until now, few reviews have discussed the antitumor activity of fucoidan and few reports have summarized detailed molecular mechanisms of its actions and antitumor challenges of fucoidan specially. In this review, the antitumor signaling pathway mechanisms related to fucoidan are elucidated as much detail as possible. Besides, the factors affecting the anticancer effects of fucoidan, the structural characteristics of fucoidan with anticancer activities and the challenges for the further development of fucoidan are also summarized and evaluated. The existing similar and different conclusions are summarized in an attempt to provide guidelines to help further research, and finally contribute to go into market as chemotherapeumtics.

Polysaccharides from the Marine Environment with Pharmacological, Cosmeceutical and Nutraceutical Potential

Carbohydrates, also called saccharides, are molecules composed of carbon, hydrogen, and oxygen. They are the most abundant biomolecules and essential components of many natural products and have attracted the attention of researchers because of their numerous human health benefits. Among carbohydrates the polysaccharides represent some of the most abundant bioactive substances in marine organisms. In fact, many marine macro- and microorganisms are good resources of carbohydrates with diverse applications due to their biofunctional properties. By acting on cell proliferation and cycle, and by modulating different metabolic pathways, marine polysaccharides (including mainly chitin, chitosan, fucoidan, carrageenan and alginate) also have numerous pharmaceutical activities, such as antioxidative, antibacterial, antiviral, immuno-stimulatory, anticoagulant and anticancer effects. Moreover, these polysaccharides have many general beneficial effects for human health, and have therefore been developed into potential cosmeceuticals and nutraceuticals. In this review we describe current advances in the development of marine polysaccharides for nutraceutical, cosmeceutical and pharmacological applications. Research in this field is opening new doors for harnessing the potential of marine natural products.

Fucoidan Suppresses the Growth of Human Acute Promyelocytic Leukemia Cells In Vitro and In Vivo

Fucoidan, a natural component of seaweeds, is reported to have immunomodulatory and anti-tumor effects. The mechanisms underpinning these activities remain poorly understood. In this study, the cytotoxicity and anti-tumor activities of fucoidan were investigated in acute myeloid leukemia (AML) cells. The human AML cell lines NB4, KG1a, HL60, and K562 were treated with fucoidan and cell cycle, cell proliferation, and expression of apoptotic pathways molecules were analyzed. Fucoidan suppressed the proliferation and induced apoptosis through the intrinsic and extrinsic pathways in the acute promyelocytic leukemia (APL) cell lines NB4 and HL60, but not in KG1a and K562 cells. In NB4 cells, apoptosis was caspase-dependent as it was significantly attenuated by pre-treatment with a pan-caspase inhibitor. P21/WAF1/CIP1 was significantly up-regulated leading to cell cycle arrest. Fucoidan decreased the activation of ERK1/2 and down-regulated the activation of AKT through hypo-phosphorylation of Thr(308) residue but not Ser(473). In vivo, a xenograft model using the NB4 cells was employed. Mice were fed with fucoidan and tumor growth was measured following inoculation with NB4 cells. Subsequently, splenic natural killer (NK) cell cytotoxic activity was also examined. Oral doses of fucoidan significantly delayed tumor growth in the xenograft model and increased cytolytic activity of NK cells. Taken together, these data suggest that the selective inhibitory effect of fucoidan on APL cells and its protective effect against APL development in mice warrant further investigation of fucoidan as a useful agent in treatment of certain types of leukemia.

Antitumor activity of fucoidan against diffuse large B cell lymphoma in vitro and in vivo

Fucoidan is one of the major sulfated polysaccharides isolated from brown seaweeds. In this study, we determined the anti-cancer activity of fucoidan on diffuse large B cell lymphoma (DLBCL) cells both in vitro and in vivo. Fucoidan inhibited the growth of DLBCL cells in a dose- and time-dependent manner, and fucoidan treatment provoked G0/G1 cell cycle arrest, which was accompanied by p21 up-regulation and cyclin D1, Cdk4, and Cdk6 down-regulation. Fucoidan also induced caspase-dependent cell apoptosis in DLBCL cell lines and primary DLBCL cell. In addition, fucoidan treatment caused the loss of mitochondrial membrane potential and the release of cytochrome c and apoptosis-inducing factor from the mitochondria into the cytosol. Fucoidan also potentiated the activities of carfilzomib in killing DLBCL cells. Oral administration of fucoidan effectively inhibited tumor growth in xenograft mouse models. Our findings reveal the novel function of fucoidan as an anti-DLBCL agent, which can be used in the clinical treatment of DLBCL.

Effect of Sulfated Polysaccharides from Brown Algae on Apoptosis of Human Peripheral Blood Lymphocytes

We studied the influence of fucoidans from brown algae Fucus evanescens, Laminaria cichorioides and Laminaria japonica on apoptosis of human peripheral blood lymphocytes. It was demonstrated that fucoidans induced lymphocyte apoptosis, increased the proportion of cells with low mitochondrial transmembrane potential, and inhibit expression of Bcl-xL gene in blood lymphocytes. These findings suggest that lymphocyte apoptosis induced by the analyzed sulfated polysaccharides is mediated by mitochondrial pathway.

Delta-tocotrienol induces apoptotic cell death via depletion of intracellular squalene in ED40515 cells

Here, we examined the effect of tocotrienols (T3) on the growth of adult T-cell leukemia (ATL) cells. All three forms (β-, γ-, and δ-T3) inhibited cell proliferation in a dose-dependent manner; δ-T3 showed the strongest growth-inhibitory effect. δ-T3 increased the G1, G2/M, and subG1 populations and induced internucleosomal DNA fragmentation. δ-T3 treatment also increased the levels of cleaved caspase-3, -6, -7, -9, and poly-ADP ribose polymerase (PARP), and this was accompanied by downregulation of Bcl-2, Bcl-xL, and XIAP. Moreover, δ-T3 decreased nuclear p65 NF-κB levels, indicating downregulation of NF-κB activity. This cytotoxic effect of δ-T3 was abrogated by squalene (SQL) but not mevalonate (MVL), farnesyl diphosphate (FPP), geranylgeranyl diphosphate (GGPP), or cholesterol (CL). δ-T3 decreased intracellular SQL levels, and inhibition of de novo cholesterol synthesis did not affect the action of SQL. Furthermore, δ-T3 significantly decreased farnesyl-diphosphate farnesyltransferase 1 (FDFT1) expression. Taken together, it is evident that δ-T3, due to its ability to potently induce apoptosis via the depletion of intracellular SQL, shows the potential to be considered a therapeutic agent in patients with ATL.

Marine polysaccharides from algae with potential biomedical applications

There is a current tendency towards bioactive natural products with applications in various industries, such as pharmaceutical, biomedical, cosmetics and food. This has put some emphasis in research on marine organisms, including macroalgae and microalgae, among others. Polysaccharides with marine origin constitute one type of these biochemical compounds that have already proved to have several important properties, such as anticoagulant and/or antithrombotic, immunomodulatory ability, antitumor and cancer preventive, antilipidaemic and hypoglycaemic, antibiotics and anti-inflammatory and antioxidant, making them promising bioactive products and biomaterials with a wide range of applications. Their properties are mainly due to their structure and physicochemical characteristics, which depend on the organism they are produced by. In the biomedical field, the polysaccharides from algae can be used in controlled drug delivery, wound management, and regenerative medicine. This review will focus on the biomedical applications of marine polysaccharides from algae.

Further studies on structure of fucoidan from brown alga Saccharina gurjanovae

A sulfated galactofucan SgF (MW 123kDa) was purified from the brown alga Saccharina gurjanovae. Polysaccharide was depolymerized by autohydrolysis at 25 and 60°C, and products were studied by mass spectrometry and (13)C NMR spectroscopy. According to results of investigation, the main chain of this polysaccharide is built of a repeating units →3)-α-L-Fucp-(2,4-OSO3(-))-(1→. Fucose chains could be sometimes terminated by (1→3)-linked galactose residues. Shorter (1→4)- and/or (1→6)-linked sulfated galactose chains are attached at positions C-2, C-3 of fucose residues. Sulfate groups can occupy positions C-2 and/or sometimes C-3 of Gal residues, but a sulfation at C-4 of the galactofucan could not be excluded. The SgF-AH25-H preparation (71kDa) was obtained by autohydrolysis of SgF at 25°C, which leaded to a selective desulfation at C-2 and, probably, to a cleavage of galactose chains, since structure of SgF-AH25-H represented a repeating unit →3)-α-l-Fucp-(4-OSO3(-))-(1→, which was definitely established by (13)C NMR spectroscopy. Galactofucan SgF and its derivative SgF-AH25-H exhibited no cytotoxic activity and leaded to about the same colony formation inhibition in colon cancer DLD-1 cells. Hence, structural simplification of SgF by lowering its molecular weight, desulfation at C-2 and removing of galactose residues by autohydrolysis at 25°C did not decrease its anticancer activity. This procedure allows obtaining standardized products which can be used as medical.

Fucoidan and cancer: a multifunctional molecule with anti-tumor potential

There is a wide variety of cancer types yet, all share some common cellular and molecular behaviors. Most of the chemotherapeutic agents used in cancer treatment are designed to target common deregulated mechanisms within cancer cells. Many healthy tissues are also affected by the cytotoxic effects of these chemical agents. Fucoidan, a natural component of brown seaweed, has anti-cancer activity against various cancer types by targeting key apoptotic molecules. It also has beneficial effects as it can protect against toxicity associated with chemotherapeutic agents and radiation. Thus the synergistic effect of fucoidan with current anti-cancer agents is of considerable interest. This review discusses the mechanisms by which fucoidan retards tumor development, eradicates tumor cells and synergizes with anti-cancer chemotherapeutic agents. Challenges to the development of fucoidan as an anti-cancer agent will also be discussed.

Biocompatible ι-carrageenan-γ-maghemite nanocomposite for biomedical applications - synthesis, characterization and in vitro anticancer efficacy

Background

Carrageenans are naturally occurring hydrophilic, polyanionic polysaccharide bioploymers with wide application in pharmaceutical industries for controlled drug delivery. Magnetic nanoparticles with their exceptional properties enable them to be an ideal candidate for the production of functional nanostructures, thus facilitating them for biomedical applications. The development of novel nanocomposite by coupling the synergistic effects of the sulfated polysaccharide (iota carrageenan) and a magnetic nanoparticle (maghemite) may offer new interesting applications in drug delivery and cancer therapy. The nanocomposite was characterized by ultraviolet–visible spectroscopy, high resolution scanning electron microscopy, dynamic light scattering analysis, Fourier transform infrared spectroscopy and powder XRD to highlight the possible interaction between the two components. Biocompatibility and the anticancer efficacy of the nanocomposite were assayed and analysed in vitro.

Results

Results suggested that iota carrageenans have electrostatically entrapped the maghemite nanoparticles in their sulfate groups. Biocompatibility of the nanocomposite (at different concentrations) against normal cell lines (HEK-293 and L6) was confirmed by MTT assay. Hoechst 33342 and 7-AAD staining studies under fluorescent microscopy revealed that the nanocomposite is able to induce appoptosis as the mode of cell death in human colon cancer cell line (HCT116). Cell apoptosis here is induced by following the ROS-mediated mitochondrial pathway, combined with downregulation of the expression levels of mRNA of XIAP and PARP-1 and upregulation of caspase3, Bcl-2 and Bcl-xL.

Conclusions

This novel nanocomposite is biocompatible with potential properties to serve in magnet aided targeted drug delivery and cancer therapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-015-0079-3) contains supplementary material, which is available to authorized users.

Systematic synthesis of low-molecular weight fucoidan derivatives and their effect on cancer cells

Low-molecular weight fucoidan derivatives with different sulfation patterns were designed, systematically synthesized, and evaluated for their anti-cancer activities against MCF-7 and HeLa cells.

In vitro anti-canine distemper virus activity of fucoidan extracted from the brown alga Cladosiphon okamuranus

Canine distemper virus (CDV) is a morbillivirus related to measles virus that infects dogs and other carnivores. CDV has a significant global impact on animal health; however, there is no current antiviral treatment for CDV infection. In recent years, it has been demonstrated that sulfated polysaccharides exhibit antiviral properties both in vivo and in vitro, despite their low cytotoxicity to host cells. Fucoidan is a sulfated polysaccharide found in the cell wall matrix of brown algae. In this study, we evaluated in vitro anti-CDV activity of fucoidan, which was derived from Cladosiphon okamuranus. Fucoidan actively inhibited CDV replication in Vero cells at a 50 % inhibitory concentration (IC50) of 0.1 µg/ml. The derived selectivity index (SI50) was >20,000. This polysaccharide likely inhibits viral infection by interference in the early steps and by inhibiting CDV-mediated cell fusion. Fucoidan may be useful in development of pharmacological strategies to treat and control CDV infection.