Sulfated polysaccharide from the red algae Gelidiella acerosa: Anticoagulant, antiplatelet and antithrombotic effects

Sulfated Polysaccharides with Anticoagulant Potential: A Review Focusing on Structure-Activity Relationship and Action Mechanism

Thromboembolism is the culprit of cardiovascular diseases, leading to the highest global mortality rate. Anticoagulation emerges as the primary approach for managing thrombotic conditions. Notably, sulfated polysaccharides exhibit favorable anticoagulant efficacy with reduced side effects. This review focuses on the structure-anticoagulant activity relationship of sulfated polysaccharides and the underlying action mechanisms. It is concluded that chlorosulfonicacid-pyridine method serves as the preferred technique to synthesize sulfated polysaccharides. The anticoagulant activity of sulfated polysaccharides is linked to the substitution site of sulfate groups, degree of substitution, molecular weight, main side chain structure, and glycosidic bond conformation. Moreover, sulfated polysaccharides exert anticoagulant activity via various pathways, including the inhibition of blood coagulation factors, activation of antithrombin III and heparin cofactor II, antiplatelet aggregation, and promotion of the fibrinolytic system.

Relationship between dietary fiber content and prebiotic potential of polysaccharides from the seaweeds of the North west coast of India

The macroalgae are a sustainable bioresource that can be harnessed for their functional food and nutraceutical applications. This study characterized the biochemical composition and bioactive potential of natural biological macromolecules, such as macroalgal polysaccharides extracted using a green, aqueous extraction process. The in-vitro antioxidant and antiglycemic activity of these polysaccharides were evaluated using model, free radical and antiglycemic compounds. The prebiotic potential of macroalgal polysaccharides were analysed based on their ability to promote the growth of two potential probiotic bacteria Lactobacillus acidophilus and L. bulgaricus and suppress the growth of enteric bacteria, Escherichia coli. Among the polysaccharides studied, the brown algal polysaccharide MPS8 MPS9 and MPS10 exhibited good antioxidant, antiglycemic and prebiotic activity. Based on infrared spectroscopy, the functional groups sulfation and carboxylation were identified in potential polysaccharides. The monosaccharide composition in the bioactive polysaccharides was determined using High Performance Anion Exchange Chromatography Pulse Amperometric detector (HPAEC-PAD). These bioactive polysaccharides were fractionated using ion exchange chromatography to purify it and further characterized using gel permeation chromatography and NMR spectroscopy. The results these polysaccharides are mainly composed of fucose and glucose which is due to the fucoidan and laminarin, respectively. Such macromolecules with high dietary fiber content and bioactivity are in global demand as functional food, nutraceutical and pharmaceutical formulations.

Dairy, Plant, and Novel Proteins: Scientific and Technological Aspects

Alternative proteins have gained popularity as consumers look for foods that are healthy, nutritious, and sustainable. Plant proteins, precision fermentation-derived proteins, cell-cultured proteins, algal proteins, and mycoproteins are the major types of alternative proteins that have emerged in recent years. This review addresses the major alternative-protein categories and reviews their definitions, current market statuses, production methods, and regulations in different countries, safety assessments, nutrition statuses, functionalities and applications, and, finally, sensory properties and consumer perception. Knowledge relative to traditional dairy proteins is also addressed. Opportunities and challenges associated with these proteins are also discussed. Future research directions are proposed to better understand these technologies and to develop consumer-acceptable final products.

Sulfation of furcellaran and its effect on hemocompatibility in vitro

In this study, furcellaran (FUR) obtained from Furcellaria lumbricalis was firstly employed for sulfation via various methods, including SO3-pyridine (SO3∙Py) complex in different aprotic solvents, chlorosulfonic acid and sulfuric acid with a "coupling" reagent N,N'-Dicyclohexylcarbodiimide. Structural characterization through FT-IR, GPC, XPS and elemental analyses confirmed the successful synthesis of 6-O-sulfated FUR derivates characterized by varying degrees of sulfation (DS) ranging from 0.15 to 0.91 and molecular weight (Mw) spanning from12.5 kDa to 2.7 kDa. In vitro clotting assays, partial thromboplastin time (aPTT), thrombin time (TT), and prothrombin time (PT) underscored the essential role of sulfate esters in conferring anticoagulant activity whereas FUR prepared via chlorosulfonic acid with DS of 0.91 reached 311.4 s in aPPT showing almost 4-fold higher anticoagulant activity than native FUR at the concentration 2 mg/mL. MTT test showed all tested samples decreased cell viability in a dose dependent manner while all of them are non-cytotoxic up to the concentration of 0.1 mg/mL. Furthermore, sulfated derivates deposited onto polyethylene terephthalate surface presented substantial decrease in platelet adhesion, as well as absence of the most activated platelet stages. These findings support the pivotal role of O-6 FUR sulfates in enhancing hemocompatibility and provide valuable insights for a comparative assessment of effective sulfating approaches.

Complex sulfated galactans from hot water extracts of red seaweed Asparagopsis taxiformis comprise carrageenan and agaran structures

Hot water extraction from the red seaweed Asparagopsis taxiformis yielded three extracts which showed sulfated galactans with a D:L-galactose ratio non consistent with carrageenan or agaran backbones. The major extract was fractionated by cetrimide precipitation and redissolution with increasing sodium chloride concentrations due to their low solubility. Seven fractions were obtained, and studied by methylation analysis, desulfation-methylation, and NMR spectroscopy of the partially hydrolyzed and the native samples. Fractions with the highest yield were those obtained at high concentrations of NaCl. They comprised both agaran and crageenan structures in considerable amounts. The main agaran structures were β-D-galactose 4-sulfate and β-D-galactose 2-sulfate units linked to α-L-galactose 2,3-disulfate residues, and β-D-galactose linked to α-L-galactose 3-sulfate or 6-sulfate, or substituted with single stubs of β-D-xylose on C3, while the carrageenan structures comprised β-D-galactose (2-sulfate) linked to α-D-galactose 3-sulfate or 2,3-disulfate, and β-D-galactose 2,4-disulfate linked to α-D-galactose 2,3-disulfate. Between the less sulfated fractions, the one obtained by solubilization in 0.5 M NaCl was mainly constituted by agarans, which included 3,6-anhydro-α-L-galactose units. Anticoagulant activity was assayed by general coagulation tests (aPTT and TT), showing a moderate action compared with heparin. This is the first detailed study of the sulfated galactans from the order Bonnemaisoniales.

Nanotechnology-driven improvisation of red algae-derived carrageenan for industrial and bio-medical applications

Algae biomass has been recognized as feedstock with diverse application including production of biofuel, biofertilizer, animal feed, wastewater treatment and bioremediation. In addition, algae species are a potential reservoir of metabolites and polymers with potential to be utilized for biomedicine, healthcare and industrial purposes. Carrageenan is one such medicinally and industrially significant polysaccharide which is extracted from red algae species (Kappaphycus alvarezii and Eucheuma denticulatum, among the common species). The extraction process of carrageenan is affected by different environmental factors and the source of biomass, which can vary and significantly impact the yield. Diverse applications of carrageenan include hydrogel beads, bio-composites, pharmacological properties, application in cosmetics, food and related industries. Carrageenan biological activities including antioxidant, anti-inflammatory, antimicrobial, and antitumor activities are significantly influenced by sulfation pattern, yield percentage and molecular weight. In addition to natural biomedical potential of carrageenan, synergetic effect of carrageenan- nanocomposites exhibit potential for further improvisation of biomedical applications. Nanotechnology driven bio-composites of carrageenan remarkably improve the quality of films, food packaging, and drug delivery systems. Such nano bio-composites exhibit enhanced stability, biodegradability, and biocompatibility, making them suitable alternatives for drug delivery, wound-healing, and tissue engineering applications. The present work is a comprehensive study to analyze biomedical and other applications of Carrageenan along with underlying mechanism or mode of action along with synergetic application of nanotechnology.

Chemical Modification of Polysaccharides: A Review of Synthetic Approaches, Biological Activity and the Structure-Activity Relationship

Natural polysaccharides are macromolecular substances with great potential owing to their wide biological activity and low toxicity. However, not all polysaccharides have significant pharmacodynamic activity; hence, appropriate chemical modification methods can be selected according to the unique structural characteristics of polysaccharides to assist in enhancing and promoting the presentation of their biological activities. This review summarizes research progress on modified polysaccharides, including common chemical modification methods, the change in biological activity following modification, and the factors affecting the biological activity of chemically modified polysaccharides. At the same time, the difficulties and challenges associated with the structural modification of natural polysaccharides are also outlined in this review. Thus, research on polysaccharide structure modification is critical for improving the development and utilization of sugar products.

Lemon gum: Non-toxic arabinogalactan isolated from Citrus × latifolia with antiproliferative property against human prostate adenocarcinoma cells

Lemon gum (LG) obtained from Citrus × latifolia in Brazil was isolated and characterized. In addition, gum biocompatibility was evaluated in vitro and in vivo by Galleria mellonella and mice model. The cytotoxicity against tumor cells was also evaluated. The ratio of arabinose:galactose: rhamnose:4-OMe-glucuronic acid was 1:0.65:0.06:0.15. Small traces of protein were detected, emphasizing the isolate purity. Molar mass was 8.08 × 10⁵ g/mol, with three different degradation events. LG showed antiproliferative activity against human prostate adenocarcinoma cancer cells, with percentage superior to 50 %. In vivo toxicity models demonstrated that LG is biocompatible polymer, with little difference in the parameters compared to control group. These results demonstrate advance in the study of LG composition and toxicity, indicating a potential for several biomedical and biotechnological future applications.

Sulfated Polysaccharides from Macroalgae-A Simple Roadmap for Chemical Characterization

The marine environment presents itself as a treasure chest, full of a vast diversity of organisms yet to be explored. Among these organisms, macroalgae stand out as a major source of natural products due to their nature as primary producers and relevance in the sustainability of marine ecosystems. Sulfated polysaccharides (SPs) are a group of polymers biosynthesized by macroalgae, making up part of their cell wall composition. Such compounds are characterized by the presence of sulfate groups and a great structural diversity among the different classes of macroalgae, providing interesting biotechnological and therapeutical applications. However, due to the high complexity of these macromolecules, their chemical characterization is a huge challenge, driving the use of complementary physicochemical techniques to achieve an accurate structural elucidation. This review compiles the reports (2016-2021) of state-of-the-art methodologies used in the chemical characterization of macroalgae SPs aiming to provide, in a simple way, a key tool for researchers focused on the structural elucidation of these important marine macromolecules.

Anti-Fatigue Effects of Lycium barbarum Polysaccharide and Effervescent Tablets by Regulating Oxidative Stress and Energy Metabolism in Rats

The purpose of this study was to investigate the anti-fatigue effect of natural Lycium barbarum polysaccharide (LBP) during exercise, develop a functional anti-fatigue effervescent tablet by applying LBP to practical products, and help patients who have difficulty swallowing conventional tablets or capsules. LBP was extracted with water, and DEAE-52 cellulose was used for purification. The chemical structure and monosaccharide composition of LBP by Fourier transform infrared spectroscopy (FI-IR) and ion chromatography (IC). Lycium barbarum polysaccharide effervescent tablets (LBPT) were prepared by mixing LBP and an excipient. Animal experiments showed that LBP and LBPT significantly increased the exhaustive swimming time in rats. LBP and LBPT improved biochemical markers in rat serum, such as lactic acid and creatine kinase, enhanced the antioxidant capacity of rat muscle, and reversed the decrease in serum glucose, ATP and glycogen content caused by exercise. Transmission electron microscopy showed that LBP and LBPT increased the density of mitochondria in rat liver. In addition, molecular experiments showed that LBP and LBPT could improve oxidative stress caused by exercise by regulating the Nrf2/HO-1 signaling pathway and regulating energy metabolism via the AMPK/PGC-1α signaling pathway.

Blood Coral Polysaccharide Helps Prevent D-Gal/LPS-Induced Acute Liver Failure in Mice

Objective

The liver protection of blood coral polysaccharide (BCP) was investigated.

Materials and Methods

We evaluated the effect of BCP on liver pathology, liver function, oxidation and inflammation-related indicators of D-Gal/LPS-induced acute liver failure (ALF) mice in vivo.

Results

Liver index and liver pathology observation in mice showed that BCP could inhibit liver tissue swelling and hemorrhage, hepatocyte damage, and inflammatory infiltration in ALF. Serum liver function results showed that BCP effectively inhibits the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), total bilirubin (TBil), alkaline phosphatase (AKP), myeloperoxidase (MPO). High dose-blood coral polysaccharide (H-BCP) was better than silymarin. Serum antioxidant and immune results showed that BCP increased the levels of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and glutathione peroxidase (GSH-Px), and inhibited the levels of malondialdehyde (MDA) and nitric oxide (NO). Also, BCP increased immunoglobulins G (IgG) and A (IgA) levels, thereby enhancing humoral immunity. Liver anti-inflammatory ELISA results showed that BCP reduced the levels of interleukin (IL)-6, IL-1β, IL-17, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ, and enhanced the level of anti-inflammatory factor IL-10. H-BCP was the most effective treatment. Real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR) of liver tissues confirmed that BCP increases the relative expression levels of antioxidant and anti-inflammatory-related cuprozinc superoxide dismutase (Cu/Zn-SOD, SOD1), manganese superoxide dismutase (Mn-SOD, SOD2), CAT, GSH, GSH-Px, and IL-10. In contrast, it inhibits inflammation-related genes IL-6, IL-1β, IL-17, TNF-α, IFN-γ, inducible nitric oxide synthase (iNOS, NOS2), and cyclooxygenase (COX)-2. In addition, BCP also inhibits the nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) and enhance B-cell inhibitor-α (IκB-α) gene relative expression in the liver, which may be related to NF-κB pathway inhibition.

Conclusion

BCP prevents D-Gal/LPS-induced ALF in mice, and its effect is concentration dependent.

A Novel Polysaccharide from AuriculariaAuricula Alleviates Thrombosis Induced by Carrageenan in Mice

The increasing incidence of cardiovascular diseases has created an urgent need for safe and effective antithrombotic agents. In this study, we aimed to elucidate the structural characteristics and antithrombotic activity of a novel polysaccharide isolated from Auriculariaauricula fruiting bodies. The purified polysaccharide AAP-b2 (12.02 kDa) was composed of mannose, glucuronic acid, glucose and xylose, with a molar ratio of 89.25:30.50:4.25:1.00. Methylation and NMR analyses showed that AAP-b2 primarily consisted of →2,3)-Manp-(1→, →3)-Manp-(1→, →4)-GlcAp-(1→ and Manp-(1→. A thrombus mouse model induced by carrageenan was used in this research to evaluate its antithrombotic effect. AAP-b2 significantly inhibited platelet aggregation, reduced the black tail length and prolonged the coagulation time, including activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT), exerting a good inhibitory effect on thrombosis in mice. The antithrombotic activity of AAP-b2 was found to be related to the inhibition of platelet activation by regulation of endothelial nitric oxide synthases (eNOs), endothelin-1 (ET-1), prostacyclin (PGI2) and thromboxane B2 (TXB2), along with the enhancement of anticoagulant activity by affecting antithrombin III (AT-III) and protein C (PC) pathways.

Sulfated Polysaccharide Extracted from the Green Algae Codium bernabei: Physicochemical Characterization and Antioxidant, Anticoagulant and Antitumor Activity

Codium bernabei is a green alga that grows on Chilean coasts. The composition of its structural polysaccharides is still unknown. Hence, the aim of this work is to isolate and characterize the hot water extracted polysaccharide fractions. For this purpose, the water extracts were further precipitated in alcohol (TPs) and acid media (APs), respectively. Both fractions were characterized using different physicochemical techniques such as GC-MS, GPC, FTIR, TGA, and SEM. It is confirmed that the extracted fractions are mainly made of sulfated galactan unit, with a degree of sulfation of 19.3% (TPs) and 17.4% (ATs) and a protein content of 3.5% in APs and 15.6% in TPs. Other neutral sugars such as xylose, glucose, galactose, fucose, mannose, and arabinose were found in a molar ratio (0.05:0.6:1.0:0.02:0.14:0.11) for TPs and (0.05:0.31:1.0:0.03:0.1:0.13) for ATs. The molecular weight of the polysaccharide samples was lower than 20 kDa. Both polysaccharides were thermally stable (Tonset > 190 °C) and showed antioxidant activity according to the ABTS•+ and DPPH tests, where TPs fractions had higher scavenging activity (35%) compared to the APs fractions. The PT and APTTS assays were used to measure the anticoagulant activity of the polysaccharide fractions. In general, the PT activity of the TPs and APs was not different from normal plasma values. The exception was the TPs treatment at 1000 µg mL−1 concentration. The APTTS test revealed that clotting time for both polysaccharides was prolonged regarding normal values at 1000 µg mL−1. Finally, the antitumor test in colorectal carcinoma (HTC-116) cell line, breast cancer (MCF-7) and human leukemia (HL-60) cell lines showed the cytotoxic effect of TPs and APs. Those results suggest the potential biotechnological application of sulfate galactan polysaccharides isolated from a Chilean marine resource.

Effects of Tetraselmis chuii Microalgae Supplementation on Anthropometric, Hormonal and Hematological Parameters in Healthy Young Men: A Double-Blind Study

The aim of this study was to evaluate the effects of Tetraselmis chuii (TC) microalgae supplementation for sixty days on hematological, anthropometric and hormonal parameters in healthy young men. Forty-six men divided into a placebo group (PG; n = 16; 20.77 ± 2.7 years; 72.14 ± 7.18 kg; 1.76 ± 0.07 m), a group supplemented with 25 mg/day of TC (SG 25; n = 15; 20.40 ± 1.40 years; 71.28 ± 8.26 kg; 1.76 ± 0.05 m) and another group supplemented with 200 mg/day of TC (SG 200; n = 15; 20.83 ± 2.45 years; 72.30 ± 11.13 kg; 1.77 ± 0.08 m) participated in this double-blind study. PG ingested 200 mg/day of lactose powder. Participants underwent 4 assessments (baseline, month 1, month 2 and desadaptation) separated in time by an interval of thirty days. At SG 25 and SG 200, significant increases in percent muscle mass, erythropoietin, insulin-like growth factor 1, free testosterone, leukocytes, neutrophils and lymphocytes were observed (p < 0.05). Decreases in the levels of percent fat mass, platelets, hematocrit and mean corpuscular hemoglobin also occurred in these groups (p < 0.05). TC supplementation induced favorable changes on anthropometric, hematological and hormonal levels. In view of the data, it seems that the most effective dose was 25 mg/day of TC.

Applications of algae to obtain healthier meat products: A critical review on nutrients, acceptability and quality

Meat constitutes one the main protein sources worldwide. However, ethical and health concerns have limited its consumption over the last years. To overcome this negative impact, new ingredients from natural sources are being applied to meat products to obtain healthier proteinaceous meat products. Algae is a good source of unsaturated fatty acids, proteins, essential amino acids, and vitamins, which can nutritionally enrich several foods. On this basis, algae have been applied to meat products as a functional ingredient to obtain healthier meat-based products. This paper mainly reviews the bioactive compounds in algae and their application in meat products. The bioactive ingredients present in algae can give meat products functional properties such as antioxidant, neuroprotective, antigenotoxic, resulting in healthier foods. At the same time, algae addition to foods can also contribute to delay microbial spoilage extending shelf-life. Additionally, other algae-based applications such as for packaging materials for meat products are being explored. However, consumers' acceptance for new products (particularly in Western countries), namely those containing algae, not only depends on their knowledge, but also on their eating habits. Therefore, it is necessary to further explore the nutritional properties of algae-containing meat products to overcome the gap between new meat products and traditional products, so that healthier algae-containing meat can occupy a significant place in the market.

NMR spectroscopy for structural elucidation of sulfated polysaccharides from red seaweeds

Some sulfated polysaccharides from red seaweeds are used as hydrocolloids. In addition, it is well known that there are sulfated galactans (carrageenans and agarans) and sulfated mannans, with remarkable biological properties, as antiviral, antitumoral, immunomodulating, antiangiogenic, antioxidant, anticoagulant, and antithrombotic activities, and so on. Knowledge of the detailed structure of the active compound is essential and difficult to acquire. The substitution patterns of the polymer chain, as degree of sulfation and position of sulfate groups, as well as other substituents of the backbone, determine their biological behavior. NMR spectroscopy is a powerful and versatile tool for structural determination. It can be used for elucidation of structures of polysaccharides from new algal sources with novel substitutions or to detect the already known structures from different algal sources, and it could even help to monitor the quality of the active compound on a productive scale. In this review, the available information about NMR spectroscopy of sulfated polysaccharides from red seaweeds is revised and rationalized, to help other researchers working in different fields to study their structures. In addition, considerations about the effects of different structural features, as well as some recording conditions on the chemical shifts of the signals are analyzed.

Anti-diabetic activity of a sulfated galactoarabinan with unique structural characteristics from Cladophora oligoclada (Chlorophyta)

The polysaccharide from green alga Cladophora oligoclada, OHSS2, was a sulfated galactoarabinan which was constituted by a backbone of (1 → 4)-β-l-arabinopyranose units with partial sulfate at C-3 of (1 → 4)-β-l-arabinopyranose units. The side chains containing (1 → 4)-β-l-arabinopyranose, (1 → 4)-β-d-galactopyranose and/or (1 → 4,6)-β-d-galactopyranose units were in C-2/C-3 of (1 → 4)-β-l-arabinopyranose units. OHSS2 had strong anti-diabetic activity in vitro assessed by inhibition of human islet amyloid polypeptide (hIAPP) aggregation. The mechanism analysis of anti-diabetic activity showed that OHSS2 diminished the production of intracellular reactive oxygen species and alleviated hIAPP aggregation-induced oxidative stress in NIT-1 cells. OHSS2 stabilized mitochondrial membrane potential, and enhanced the mitochondrial complex I, II or III activity and ATP level. Thus, OHSS2 effectively protected mitochondria from hIAPP aggregation-induced damage. Furthermore, OHSS2 was co-localized with mitochondria and could have a direct influence on mitochondrial function. These results revealed that OHSS2 had potential as a novel anti-diabetic agent.

Cardiovascular Protective Effects of Plant Polysaccharides: A Review

Cardiovascular disease is a kind of heart, brain, and blood vessel injury disease by the interaction of various pathological factors. The pathogenesis of cardiovascular disease is complex with various risk factors, including abnormally elevated blood pressure, glucose, and lipid metabolism disorders, atherosclerosis, thrombosis, etc. Plant polysaccharides are a special class of natural products derived from plant resources, which have the characteristics of wide sources, diverse biological activities, and low toxicity or side effects. Many studies have shown that plant polysaccharides improve cardiovascular diseases through various mechanisms such as anti-oxidative stress, restoring the metabolism of biological macromolecules, regulating the apoptosis cascade to reduce cell apoptosis, and inhibiting inflammatory signal pathways to alleviate inflammation. This article reviews the pharmacological effects and protective mechanisms of some plant polysaccharides in modulating the cardiovascular system, which is beneficial for developing more effective drugs with low side effects for management of cardiovascular diseases.

Seaweed polysaccharides: Emerging extraction technologies, chemical modifications and bioactive properties

Nowadays, consumers are increasingly aware of the relationship between diet and health, showing a greater preference of products from natural origin. In the last decade, seaweeds have outlined as one of the natural sources with more potential to obtain bioactive carbohydrates. Numerous seaweed polysaccharides have aroused the interest of the scientific community, due to their biological activities and their high potential on biomedical, functional food and technological applications. To obtain polysaccharides from seaweeds, it is necessary to find methodologies that improve both yield and quality and that they are profitable. Nowadays, environmentally friendly extraction technologies are a viable alternative to conventional methods for obtaining these products, providing several advantages like reduced number of solvents, energy and time. On the other hand, chemical modification of their structure is a useful approach to improve their solubility and biological properties, and thus enhance the extent of their potential applications since some uses of polysaccharides are still limited. The present review aimed to compile current information about the most relevant seaweed polysaccharides, available extraction and modification methods, as well as a summary of their biological activities, to evaluate knowledge gaps and future trends for the industrial applications of these compounds.Key teaching pointsStructure and biological functions of main seaweed polysaccharides.Emerging extraction methods for sulfate polysaccharides.Chemical modification of seaweeds polysaccharides.Potential industrial applications of seaweed polysaccharides.Biological activities, knowledge gaps and future trends of seaweed polysaccharides.

Perspective on the Therapeutic Applications of Algal Polysaccharides

Abstract

Algae are an enormous source of polysaccharides and have gained much interest in human flourishing as organic drugs. Algal polysaccharides have aroused interest in the health sector owing to the various bioactivities namely anticancer, antiviral, immunoregulation, antidiabetic and antioxidant effects. The research community has comprehensively described the importance of algal polysaccharides regarding their extraction, purification, and potential use in various sectors. However, regardless of all the intriguing properties and potency in the health sector, these algal polysaccharides deserve detailed investigation. Hence, the present review emphasizes extensively on the previous and latest developments in the extraction, purification, structural properties and therapeutic bioactivities of algal polysaccharides to upgrade the knowledge for further advancement in this area of research. Moreover, the review also addresses the challenges, prospective research gaps and future perspective. We believe this review can provide a boost to upgrade the traditional methods of algal polysaccharide production for the development of efficacious drugs that will promote human welfare.

Graphic Abstract

Marine sulfated polysaccharides as potential antiviral drug candidates to treat Corona Virus disease (COVID-19)

The viral infection caused by SARS-CoV-2 has increased the mortality rate and engaged several adverse effects on the affected individuals. Currently available antiviral drugs have found to be unsuccessful in the treatment of COVID-19 patients. The demand for efficient antiviral drugs has created a huge burden on physicians and health workers. Plasma therapy seems to be less accomplishable due to insufficient donors to donate plasma and low recovery rate from viral infection. Repurposing of antivirals has been evolved as a suitable strategy in the current treatment and preventive measures. The concept of drug repurposing represents new experimental approaches for effective therapeutic benefits. Besides, SARS-CoV-2 exhibits several complications such as lung damage, blood clot formation, respiratory illness and organ failures in most of the patients. Based on the accumulation of data, sulfated marine polysaccharides have exerted successful inhibition of virus entry, attachment and replication with known or unknown possible mechanisms against deadly animal and human viruses so far. Since the virus entry into the host cells is the key process, the prevention of such entry mechanism makes any antiviral strategy effective. Enveloped viruses are more sensitive to polyanions than non-enveloped viruses. Besides, the viral infection caused by RNA virus types embarks severe oxidative stress in the human body that leads to malfunction of tissues and organs. In this context, polysaccharides play a very significant role in providing shielding effect against the virus due to their polyanionic rich features and a molecular weight that hinders their reactive surface glycoproteins. Significantly the functional groups especially sulfate, sulfate pattern and addition, uronic acids, monosaccharides, glycosidic linkage and high molecular weight have greater influence in the antiviral activity. Moreover, they are very good antioxidants that can reduce the free radical generation and provokes intracellular antioxidant enzymes. Additionally, polysaccharides enable a host-virus immune response, activate phagocytosis and stimulate interferon systems. Therefore, polysaccharides can be used as candidate drugs, adjuvants in vaccines or combination with other antivirals, antioxidants and immune-activating nutritional supplements and antiviral materials in healthcare products to prevent SARS-CoV-2 infection.

Prolonged release and shelf-life of anticoagulant sulfated polysaccharides encapsulated with ZIF-8

Natural active polysaccharides are attracting increased attention from pharmaceutical industries for their valuable biological activities. However, the application of polysaccharides has been restricted due to their relatively large molecular weight, complex structure, and instability. Metal-organic frameworks (MOFs) have emerged to help deliver cargo to specific locations, achieving the objectives of eliminating the potential damage to the body, protecting the drugs, and improving therapeutic effectiveness. Here, a pH-responsive zeolitic imidazolate framework (ZIF-8) was synthesized to encapsulated three sulfated polysaccharides (heparin, fucan sulfate, fucosylated chondroitin sulfate) and a non-sulfated polysaccharide, hyaluronic acid. The resulting polysaccharides@ZIF-8 biocomposites showed differences in terms of morphology, particle size, encapsulation, and release efficiency. These biocomposites retained antithrombotic activity and the framework ZIF-8 effectively protected these polysaccharides from degradation and prolonged shelf-life of the anticoagulants from the unfavorable environment.

Protective effect against gastric mucosa injury of a sulfated agaran from Acanthophora spicifera

In this study, a polysaccharide from marine alga Acanthophora spicifera (PAs) was isolated and structurally characterized. Its protective potential against chemically-induced gastric mucosa injury was evaluated. The gel permeation chromatography experiments and spectroscopy spectrum showed that PAs is a sulfated polysaccharide with a high molecular mass (6.98 × 10⁵g/mol) and degree of sulfation of 1.23, exhibiting structural characteristic typical of an agar-type polysaccharide. Experimental results demonstrated that PAs reduced the hemorrhagic gastric injury, in a dose-dependent manner. Additionally, PAs reduced the intense gastric oxidative stress, measured by glutathione (GSH) and malondialdehyde (MDA) levels. PAs also prevented the reduction of mucus levels adhered to the gastric mucosa, promoted by the aggressive effect of ethanol. In summary, the sulfated polysaccharide from A. spicifera protected the gastric mucosa through the prevention of lipid peroxidation and enhanced the defense mechanisms of the gastric mucosa, suggesting as a promising functional food as gastroprotective agent.

PL-S2, a homogeneous polysaccharide from Radix Puerariae lobatae, attenuates hyperlipidemia via farnesoid X receptor (FXR) pathway-modulated bile acid metabolism

Polysaccharides are important active constituents of Radix Puerariae lobatae (RPL). In this study, a novel homogeneous polysaccharide from RPL was successfully obtained by HP-20 macroporous resin and purified by Sepharose G-100 column chromatography. Nuclear magnetic resonance (NMR) analysis showed that the main glycosidic bonds were composed of α-1,3-linked and α-1,4-linked glucose. The molecular weight of PL-S2 was 18.73 kDa. The hypolipidemic effect of PL-S2 on hyperlipidemic rats was evaluated in histopathology and metabolomics analyses. PL-S2 significantly reduced plasma lipid levels and inhibited bile acid metabolism. We also demonstrated that treatment with PL-S2 activated FXR, CYP7A1, BESP, and MRP2 in rat liver. Our findings first indicate that PL-S2 decreases plasma lipid levels in hyperlipidemic rats by activating the FXR signaling pathway and promoting bile acid excretion. Therefore, PL-S2 derived from RPL is implicated as a functional food factor with lipid-regulating activity, and highlighted as a potential food supplement for the treatment of hyperlipidemia.