Sulfation, anticoagulant and antioxidant activities of polysaccharide from green algae Enteromorpha linza

Anticoagulant Activity of Sulfated Ulvan Isolated from the Green Macroalga Ulva rigida

(1) Background: Brown and red algal sulfated polysaccharides have been widely described as anticoagulant agents. However, data on green algae, especially on the Ulva genus, are limited. This study aimed at isolating ulvan from the green macroalga Ulva rigida using an acid- and solvent-free procedure, and investigating the effect of sulfate content on the anticoagulant activity of this polysaccharide. (2) Methods: The obtained ulvan fraction was chemically sulfated, leading to a doubling of the polysaccharide sulfate content in a second ulvan fraction. The potential anticoagulant activity of both ulvan fractions was then assessed using different assays, targeting the intrinsic and/or common (activated partial thromboplastin time), extrinsic (prothrombin time), and common (thrombin time) pathways, and the specific antithrombin-dependent pathway (anti-Xa and anti-IIa), of the coagulation cascade. Furthermore, their anticoagulant properties were compared to those of commercial anticoagulants: heparin and Lovenox®. (3) Results: The anticoagulant activity of the chemically-sulfated ulvan fraction was stronger than that of Lovenox® against both the intrinsic and extrinsic coagulation pathways. (4) Conclusion: The chemically-sulfated ulvan fraction could be a very interesting alternative to heparins, with different targets and a high anticoagulant activity.

Sulfated polysaccharide isolated from Globularia alypum L.: Structural characterization, in vivo and in vitro anticoagulant activity, and toxicological profile

A sulfated polysaccharide from Globularia alypum L. (GASP) was extracted with a yield of 14.2%. GASP is composed mostly of sulfate and total sugars (13.29% and 71.56%, respectively) with small amount of proteins and lipids. The chemical and structural characterization was studied by Infra-Red spectroscopic and gas chromatography-mass spectrometry (GC-MS). GASP composed of eight carbohydrates where galactose, glucose, and mannose are the major compounds (33.47%, 26.71% and 18.21%, respectively). The in vitro and in vivo anticoagulant activities in rats were tested using the standard coagulation assays activated partial thromboplastin time (aPTT), prothrombine time (TT) and thrombin time (PT) tests. Both doses of GASP (200 and 500 mg/kg b.w) displayed a significant in vitro (1.22 and 1.33-fold, 1.17 and 1.27-fold, and 1.21 and 1.26-fold, respectively) and in vivo (1.47 and 2.52-fold; 1.20 and 1.43-fold; 1.21 and 1.40-fold, respectively) compared with the control. Toxicity studies on liver performed by the catalytic activity of transaminases in plasma, oxidative stress markers and hepatic morphological changes indicated that GASP at both doses are not toxics. The important pharmacological and toxicological profile of GASP revealed that this compound may be used as a novel and effective drug.

Directional preparation of anticoagulant-active sulfated polysaccharides from Enteromorpha prolifera using artificial neural networks

The sulfated polysaccharides from Enteromorpha prolifera (PE) are a potential source of anticoagulant agents. In this study, the PE was degraded by specific degradase and five hydrolysis products with different molecular weights were prepared. The product of 206 kDa is a kind of high rhamnose-containing polysaccharide with sulfate ester (34.29%). It could effectively prolong the activated partial thromboplastin time (APTT), which indicated inhibition of the intrinsic coagulation pathway. The artificial neural network (ANN) was built to realize the directional preparation of anticoagulant-active polysaccharides. Based on monitoring glucose concentration on-line, a visualization system of enzymatic hydrolysis was developed to simplify the operation of ANN. The model could be further applied to predict molecular weights of polysaccharides that possess diverse biological activities.

Total fractionation and characterization of the water-soluble polysaccharides isolated from Enteromorpha intestinalis

Water-soluble crude polysaccharides (WE) were extracted from the Enteromorpha intestinalis with hot water and further fractionated on a DEAE-52 Cellulose chromatography column and Sepharose CL-6B gel-permeation chromatography to afford one neutral fraction (WE-11) and five acidic fractions (WE-21, WE-31, WE-32, WE-41 and WE-42). Monosaccharide analysis showed that WE-32, WE-41 and WE-42 were all composed of Rha and GlcA, WE-21 and WE-31 contained Man and Rha, and WE-11 was composed of GlcA and Xyl. The molecular weight of WE-11, WE-21, WE-31 WE-32, WE-41 and WE-42 were 2.23 × 10⁵, 1.42 × 10⁵, 1.42 × 10⁵, 2.62 × 10⁴, 2.23 × 10⁵ and 8.09 × 10^4, respectively. Then, antioxidant activities in vitro were investigated on the basis of DPPH radical assay, reducing power assay, hydroxyl radical assay and superoxide radical assay. Of all polysaccharides fractions, WE-32 and WE-41 had relative higher content of sulfate and GlcA. In addition, WE-32 and WE-41 showed relative stronger antioxidant activity and inhibitory activity in vitro. The antioxidant activities of polysaccharides were not a function of a single factor but a combination of several factors, such as monosaccharide composition, molecular weights, protein content, uronic acid and sulfate content.

Recent Advances in Marine Algae Polysaccharides: Isolation, Structure, and Activities

Marine algae have attracted a great deal of interest as excellent sources of nutrients. Polysaccharides are the main components in marine algae, hence a great deal of attention has been directed at isolation and characterization of marine algae polysaccharides because of their numerous health benefits. In this review, extraction and purification approaches and chemico-physical properties of marine algae polysaccharides (MAPs) are summarized. The biological activities, which include immunomodulatory, antitumor, antiviral, antioxidant, and hypolipidemic, are also discussed. Additionally, structure-function relationships are analyzed and summarized. MAPs' biological activities are closely correlated with their monosaccharide composition, molecular weights, linkage types, and chain conformation. In order to promote further exploitation and utilization of polysaccharides from marine algae for functional food and pharmaceutical areas, high efficiency, and low-cost polysaccharide extraction and purification methods, quality control, structure-function activity relationships, and specific mechanisms of MAPs activation need to be extensively investigated.

Sulphated polysaccharide isolated from Sargassum vulgare: Characterization and hypolipidemic effects

A sulphated polysaccharide from brown algae Sargassum vulgare (SVSP) was extracted and examined with respect to chemical, structural characterization and hypolipidemic effects. SVSP consisted mainly of sulphate and total sugars with low levels of lipids and proteins. Its structure was studied by nuclear magnetic resonance (RMN), gas chromatography-mass spectrometry (GC-MS), infra-red spectroscopic, differential scanning calorimetry and X-ray diffraction analysis. Allowing us therefore to revealed that SVSP was composed of glucose, rhamnose, xylose, galactose, mannose and arabinose with XRD pattern that was typical for a semi-crystalline polymer and complexities of the spectra reflected its homogeneous structure. The administration of SVSP to obese rats is effective in lowering the body weight and inhibiting the lipase activity leading to notable regulation of lipid profile, increasing the activities of antioxidant enzymes, limiting lipid peroxidation; and protects liver-kidney functions proved by a decrease in the levels of toxicity parameters in blood, confirmed by histological study.

Antioxidant and Antiproliferative Activity of Asparagopsis taxiformis

BACKGROUND

Asparagopsis taxiformis (Rhodophyta) is a species of red algae belonging to the family Bonnemaisoniaceae. The objective of the present study was to evaluate antioxidant and antiproliferative activity of four fractions (petroleum ether, chloroform, ethyl acetate, and methanol) of A. taxiformis.

MATERIALS AND METHODS

The red seaweed, A. taxiformis was collected from Mandapam Coastal Region, Gulf of Mannar, Tamil Nadu. Epiphytes present in algal extracts were cleaned and washed with seawater and fresh water. In vitro antioxidant activity was determined by hydrogen peroxide scavenging, ferric reducing antioxidant power, superoxide radical, metal-chelating activity, and phosphomolybdenum reduction assay. Further, the cytotoxic activity was evaluated using brine shrimp lethality assay. This method is rapid, reliable, inexpensive, and convenient as compared to other cytotoxicity assays. Gallic acid, ethylenediaminetetraacetic acid, ascorbic acid, and quercetin were used as reference antioxidant compounds.

RESULTS

Reducing power of chloroform extract increased with increasing concentration of the extract. The radical scavenging activity of extracts was in the following order: ascorbic acid > methanol > chloroform > petroleum ether > ethyl acetate. Highest metal-chelating activity was observed in petroleum ether fractions (63%). Reduction of Mo (VI) to Mo (V) increased in methanol extract (27%) at 100 μg/ml. Moreover, all fractions had an inhibitory effect on the formation of hydroxyl radicals. Results showed that ethyl acetate, methanol, and petroleum ether fractions exhibited potent cytotoxic activity with median lethal concentration values of 84.33, 104.4, and 104.4 μg/ml, respectively.

CONCLUSION

Thus, the results showed that red algae possess strong antioxidant and cytotoxic activity that suggests their possible use in the development of pharmaceutical drugs.

SUMMARY

Various fractions of red algae Asparagopsis taxiformis was evaluated for in vitro antioxidant and antiproliferative studies. All results indicate potential use of red algae for drug development. Abbreviations Used: Mo: Molybdenum, AlCl3.H2O: Aluminum chloride, NaNO2: Sodium nitrite, NaOH: Sodium hydroxide, H2O2: Hydrogen peroxide, NADH: Nicotinamide adenine dinucleotide, NBT: Nitroblue tetrazolium chloride, PMS: Phenyl methanesulfonate, FeCl2: Ferrous chloride.

Sulfated modification, characterization, and antioxidant and moisture absorption/retention activities of a soluble neutral polysaccharide from Enteromorpha prolifera

A purified polysaccharide from Enteromorpha prolifera (PEP) with a molecular mass of 147.8kDa, was prepared by hot-water extraction method and purified by anion-exchange chromatography and gel filtration chromatography. Low Mw polysaccharide of E. prolifera (LEP, 44.8kDa) was obtained by enzymatic degradation. Sulfated derivatives of the two different Mw polysaccharides were synthesized by chlorosulfonic acid/pyridine method, and the degrees of substitution of SPEP and SLEP were 0.57 and 0.81, respectively. Physicochemical properties and FT-IR spectra showed that enzymatic degradation and sulfated modification of polysaccharides were successful. ¹³C NMR analysis showed that the sulfate groups mainly attached to C-6 of rhamnose. Moreover, the study revealed that enzymatic degradation and sulfated modification of polysaccharides improved significantly superoxide, hydroxyl and DPPH radicals scavenging activities in vitro, and enhanced obviously moisture absorption/retention capacities. Therefore, these results demonstrated that molecular weight and sulfate groups had obvious effects on antioxidant activities and moisture absorption/retention abilities of the polysaccharides from E. prolifera.

Comparative Analysis of the Effects of Hydroxysafflor Yellow A and Anhydrosafflor Yellow B in Safflower Series of Herb Pairs Using Prep-HPLC and a Selective Knock-Out Approach

The flower of Carthamus tinctorius L. (Carthami Flos, safflower), important in traditional Chinese medicine (TCM), is known for treating blood stasis, coronary heart disease, hypertension, and cerebrovascular disease in clinical and experimental studies. It is widely accepted that hydroxysafflor yellow A (HSYA) and anhydrosafflor yellow B (ASYB) are the major bioactive components of many formulae comprised of safflower. In this study, selective knock-out of target components such as HSYA and ASYB by using preparative high performance liquid chromatography (prep-HPLC) followed by antiplatelet and anticoagulation activities evaluation was used to investigate the roles of bioactive ingredients in safflower series of herb pairs. The results showed that both HSYA and ASYB not only played a direct role in activating blood circulation, but also indirectly made a contribution to the total bioactivity of safflower series of herb pairs. The degree of contribution of HSYA in the safflower and its series herb pairs was as follows: Carthami Flos-Ginseng Radix et Rhizoma Rubra (CF-GR) > Carthami Flos-Sappan Lignum (CF-SL) > Carthami Flos-Angelicae Sinensis Radix (CF-AS) > Carthami Flos-Astragali Radix (CF-AR) > Carthami Flos-Angelicae Sinensis Radix (CF-AS) > Carthami Flos-Glycyrrhizae Radix et Rhizoma (CF-GL) > Carthami Flos-Salviae Miltiorrhizae Radix et Rhizoma (CF-SM) > Carthami Flos (CF), and the contribution degree of ASYB in the safflower and its series herb pairs: CF-GL > CF-PS > CF-AS > CF-SL > CF-SM > CF-AR > CF-GR > CF. So, this study provided a significant and effective approach to elucidate the contribution of different herbal components to the bioactivity of the herb pair, and clarification of the variation of herb-pair compatibilities. In addition, this study provides guidance for investigating the relationship between herbal compounds and the bioactivities of herb pairs. It also provides a scientific basis for reasonable clinical applications and new drug development on the basis of the safflower series of herb pairs.

Inhibition of hydrogen peroxide induced injuring on human skin fibroblast by Ulva prolifera polysaccharide

Ulva prolifera can protect human skin fibroblast from being injured by hydrogen peroxide. This work studied the composition of Ulva prolifera polysaccharide and identified its physicochemical properties. The results showed that the cell proliferation of 0.5mg/mL crude polysaccharide was 154.4% of that in negative control group. Moreover, ROS detection indices, including DCFH-DA, GSH-PX, MDA and CAT, indicated that crude polysaccharide could improve cellular ability to scavenge free radical and decrease the injury on human skin fibroblast by hydrogen peroxide. In purified polysaccharide, the activity of fraction P1-1 was the highest, with 174.6% of that in negative control group. The average molecular weight of P1-1 was 137kD with 18.0% of sulfate content. This work showed the inhibition of hydrogen peroxide induced injuries on human skin fibroblast by Ulva prolifera polysaccharide, which may further evaluate the application of U. prolifera on cosmetics.

Reviews on Mechanisms of In Vitro Antioxidant Activity of Polysaccharides

It is widely acknowledged that the excessive reactive oxygen species (ROS) or reactive nitrogen species (RNS) induced oxidative stress will cause significant damage to cell structure and biomolecular function, directly or indirectly leading to a number of diseases. The overproduction of ROS/RNS will be balanced by nonenzymatic antioxidants and antioxidant enzymes. Polysaccharide or glycoconjugates derived from natural products are of considerable interest from the viewpoint of potent in vivo and in vitro antioxidant activities recently. Particularly, with regard to the in vitro antioxidant systems, polysaccharides are considered as effective free radical scavenger, reducing agent, and ferrous chelator in most of the reports. However, the underlying mechanisms of these antioxidant actions have not been illustrated systematically and sometimes controversial results appeared among various literatures. To address this issue, we summarized the latest discoveries and advancements in the study of antioxidative polysaccharides and gave a detailed description of the possible mechanisms.

Stimulation of RAW264.7 macrophages by sulfated Escherichia coli K5 capsular polysaccharide in vitro

The aim of the present study was to explore the immunomodulatory effects of sulfated K5 polysaccharide derivatives on RAW264.7 macro-phage cells, and to further elucidate the structure‑activity relationship. In the present study, chemically sulfated polysaccharides were derived from Escherichia coli K5 capsular polysaccharide (K5PS), and molecular weight determination, sugar analysis, and other physical and chemical characterizations were performed on the derived polysaccharides. Enzyme‑linked immunosorbent assay and reverse transcription‑polymerase chain reaction analyses demonstrated that K5‑OS2 stimulated murine RAW264.7 macrophage cells to release TNF‑α and IL‑1β proinflammatory cytokines. K5‑OS2 also induced the expression of inducible nitric oxide synthase iNOS, which is responsible for the production of nitric oxide. In addition, K5‑OS2 markedly induced macrophage‑mediated cytotoxicity against cancer cells and promoted the phagocytic activity of the RAW264.7 cells. Therefore, K5‑OS2 activated macrophages and acted as a potent immunomodulator. Observations of the present study also indicated that sulfation modification enhanced the immune‑enhancing activity of K5PS, and that the high sulfation in the O‑position of K5PS may be required for the immunomodulatory activities of the Escherichia coli K5 capsular polysaccharide.

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.

Ecotin: Exploring a feasible antithrombotic profile

Ecotin is an Escherichia coli-derived protein that can inhibit serine proteases. It has been suggested that this protein (ecotin-WT) and some of its variants could be used to develop a prototype to treat thrombosis. In this work, the effect of ecotin-WT and a variant of this protein harboring two mutations (Met84Arg and Met85Arg, ecotin-RR) were analyzed to determine their ability to prevent thrombus formation using in vivo models. Ecotins were analyzed in vitro using the coagulation tests. An in vivo venous thrombosis rat model and a pulmonary thromboembolism mouse model were used to investigate the antithrombotic activity. The bleeding time in rats using a tail-transection model was evaluated as a possible side effect caused by the administration of these proteins. Ecotin-RR was more effective in inhibiting thrombin than ecotin-WT. Both ecotins presented similar mechanisms of anticoagulation activity and were able to decrease thrombus formation. In contrast, only ecotin-RR increased survival rates in the in vivo pulmonary thromboembolism model, reinforcing the antithrombotic activity of ecotin-RR. Ecotin-WT and more so ecotin-RR showed potent antithrombotic effects, not associated with bleeding. The presented results indicate that ecotin-WT and ecotin-RR may be new scaffolds that could be used to develop anticoagulation molecules.

Sulfated Polysaccharides Isolated from Cloned Grateloupia filicina and Their Anticoagulant Activity

Sulfated polysaccharides (GSP) were isolated from the cloned Grateloupia filicina which was cultured in Jiaozhou Bay, Qingdao, China. The yield of GSP was 15.75%. The total sugar and sulfate were 40.90 and 19.89%, respectively. And the average molecular weight was 11.7 KDa. The results of neutral sugar analysis showed that GSP was mainly sulfated polysaccharides of galactose. The experiments for activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT) anticoagulant assays in vitro indicated that GSP was a good potential anticoagulant. Therefore, this study supplied new thought for the cloned Grateloupia filicina exploitation of high-value products.

Antioxidant activity of high sulfate content derivative of ulvan in hyperlipidemic rats

High sulfate content derivative of polysaccharide (HU) from Ulva pertusa (Chlorophyta) showed strong antioxidant activity in vitro. In the present study, in vivo antioxidant activity were tested in liver of hyperlipidemic rats including malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT). The HU groups at the doses of 125 mg/kg and 250 mg/kg showed stronger activity on SOD than hyperlipidemimia group (P<0.01). The HU groups at the doses of 125 mg/kg and 500 mg/kg could increase the activities of GSH-Px obviously (P<0.01) as compared with hyperlipidemic rats. It was likely that the sulfate content had significant effect on the antioxidant activity in vivo. On the other hand, it may be concluded that, probably due to its antioxidant effects, HU is effective in the protection of liver tissue from the damage of cholesterol-rich diet rats and that the HU may be of use as an antihyperlipidemia agent.

Overview on biological activities and molecular characteristics of sulfated polysaccharides from marine green algae in recent years

Among the three main divisions of marine macroalgae (Chlorophyta, Phaeophyta and Rhodophyta), marine green algae are valuable sources of structurally diverse bioactive compounds and remain largely unexploited in nutraceutical and pharmaceutical areas. Recently, a great deal of interest has been developed to isolate novel sulfated polysaccharides (SPs) from marine green algae because of their numerous health beneficial effects. Green seaweeds are known to synthesize large quantities of SPs and are well established sources of these particularly interesting molecules such as ulvans from Ulva and Enteromorpha, sulfated rhamnans from Monostroma, sulfated arabinogalactans from Codium, sulfated galacotans from Caulerpa, and some special sulfated mannans from different species. These SPs exhibit many beneficial biological activities such as anticoagulant, antiviral, antioxidative, antitumor, immunomodulating, antihyperlipidemic and antihepatotoxic activities. Therefore, marine algae derived SPs have great potential for further development as healthy food and medical products. The present review focuses on SPs derived from marine green algae and presents an overview of the recent progress of determinations of their structural types and biological activities, especially their potential health benefits.