Dermatan sulfate from beef mucosa: structure, physicochemical and biological properties of fractions prepared by chemical depolymerization and anion-exchange chromatography

Radical Depolymerization of Alginate Extracted from Moroccan Brown Seaweed Bifurcaria bifurcata

The degradation of alginate extracted from Moroccan Bifurcaria bifurcata has not been fully established to date. In this work, we report the extraction and the characterization of alginate (ASBB) from the brown algae B. bifurcata, as well as the production of oligo-alginates (OGABs) by using a green chemistry process. The depolymerization of ASBB was carried out by controlled radical hydrolysis through our green chemistry process using a hydrogen peroxide (H2O2) catalyst. The molecular weight (Mw) and degree of polymerization (DP) distribution of oligo-alginates (OGABs) obtained were then characterized by HPLC size exclusion chromatography (SEC) and high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Structural characterization revealed that after 6 h of depolymerization of ASBB, we obtained OGABs with Mw ≤ 5.5 kDa and 2 ≤ DP ≤ 24. These results highlight the effectiveness of the controlled radical hydrolysis of alginate to produce good yields of alginate fractions with controlled Mw with a known polymerization degree (DP) and without altering properties of oligo-alginates. Bifurcaria bifurcata can be a potential source of alginate and oligo-alginates given its abundance on the northwest Atlantic coast. The production and characterization of oligo-alginates promote their exploitation in the cosmetic, pharmaceutic, and agriculture fields.

Structural analysis and anticoagulant activities of the novel sulfated fucan possessing a regular well-defined repeating unit from sea cucumber

Sulfated fucans, the complex polysaccharides, exhibit various biological activities. Herein, we purified two fucans from the sea cucumbers Holothuria edulis and Ludwigothurea grisea. Their structures were verified by means of HPGPC, FT-IR, GC–MS and NMR. As a result, a novel structural motif for this type of polymers is reported. The fucans have a unique structure composed of a central core of regular (1→2) and (1→3)-linked tetrasaccharide repeating units. Approximately 50% of the units from L. grisea (100% for H. edulis fucan) contain sides of oligosaccharides formed by nonsulfated fucose units linked to the O-4 position of the central core. Anticoagulant activity assays indicate that the sea cucumber fucans strongly inhibit human blood clotting through the intrinsic pathways of the coagulation cascade. Moreover, the mechanism of anticoagulant action of the fucans is selective inhibition of thrombin activity by heparin cofactor II. The distinctive tetrasaccharide repeating units contribute to the anticoagulant action. Additionally, unlike the fucans from marine alga, although the sea cucumber fucans have great molecular weights and affluent sulfates, they do not induce platelet aggregation. Overall, our results may be helpful in understanding the structure-function relationships of the well-defined polysaccharides from invertebrate as new types of safer anticoagulants.

Antithrombin activity and disaccharide composition of dermatan sulfate from different bovine tissues

Dermatan sulfate is a glycosaminoglycan that selectively inhibits the action of thrombin through interaction with heparin cofactor II. Unlike heparin it does not interact with other coagulation factors and is able to inhibit thrombin associated with clots. This property has made dermatan sulfate an attractive candidate as an antithrombotic drug. Previous studies have showed that dermatan sulfate derived from porcine/bovine intestinal mucosa/skin or marine invertebrates is capable of stimulating heparin cofactor II-mediated thrombin inhibition in vitro. This biological activity is reported for the first time in this study using dermatan sulfate derived from mammalian tissues other than intestinal mucosa or skin. Ten different bovine tissues including the aorta, diaphragm, eyes, large and small intestine, esophagus, skin, tendon, tongue, and tongue skin were used to prepare dermatan sulfate-enriched fractions by anion exchange chromatography and acetone precipitation. Heparin cofactor II/dermatan sulfate-mediated thrombin inhibition measured in vitro revealed activity comparable to or higher than the commercial standard with 2-fold differences observed between some tissues. Analysis of the extracted dermatan sulfate using fluorophore-assisted carbohydrate electrophoresis revealed significant differences in the relative percentage of all the mono-sulfated disaccharides, in particular the predominant mammalian disaccharide uronic acid-->N-acetyl-D-galactosamine-4-O-sulfate, confirming previous reports regarding variations in sulfation in dermatan sulfate from different tissues. Overall, these findings demonstrate that dermatan sulfate extracted from a range of bovine tissues exhibits in vitro antithrombin activity equivalent to or higher than that observed for porcine intestinal mucosa, identifying additional sources of dermatan sulfate as potential antithrombotic agents.

Dermatan carriers for neovascular transport targeting, deep tumor penetration and improved therapy

A new approach to functional tumor imaging and deep interstitial penetration of therapeutic agents is to target the upregulated transport activities of neovascular endothelium. Agents are formulated with the anionic glycosaminoglycan, 435-type dermatan sulfate (DS 435, 22.2 kDa), chemically enriched for oligosaccharide sequences that confer high heparin cofactor II binding and correlate with high tumor uptake. A magnetic resonance (MR) imaging agent is prepared as self-assembling, 5-nm nanoparticles of Fe(+3):deferoxamine (Fe:Df) bound by strong ion pairing to DS, which forms the outer molecular surface (Zeta potential -39 mV). On intravenous (i.v.) injection, Fe:Df-DS rapidly (<7 min) and selectively targets and transports at high capacity across the neovascular endothelium of large (2-cm) Dunning prostate R3327 AT1 rat tumors; releases from the abluminal surface, due to reversible binding of its multivalent, low-affinity (K(d) 10(-4) to 10(-5)) oligosaccharide ligands; and progressively penetrates the interstitium from its initial site of high uptake in the well-perfused outer tumor rim, into the poorly perfused central subregion. By gamma camera imaging of (67)Ga:Df-DS, the agent avoids normal site uptake and clears through the kidneys with a t(1/2) of 18 min. A therapeutic formulation of DS-doxorubicin (DS-dox) is prepared by aqueous high-pressure homogenization of the drug and DS 435, which produces 11-nm nanoparticles of doxorubicin cores coated with DS (Zeta potential -39 mV) that are stable to lyophilization. Microscopic analysis of tumor sections 3 h after i.v. injection shows much higher overall tumor fluorescence and deeper matrix penetration for DS-dox than conventional doxorubicin (dox): >75 vs. <25 microm between the nearest microvessels. DS-dox also results in enhanced tumor-cell internalization and nuclear localization of the drug. Therapeutic efficacies in established (250 +/- 15 mg) MX-1 human breast tumor xenografts at maximum tolerated doses (MTDs) are (control vehicle, dox, dox-DS) (a) median days to 7-fold tumor growth: 8.3, 25.6 (p = 0.0007), 43.2 (p = 0.0001); (b) complete 90-day tumor regressions: 0/10, 0/10, 4/10. These results demonstrate the potential to develop a novel class of carbohydrate-targeted neovascular transport agents for sensitive, high-resolution (100-microm) MR imaging and improved treatment of larger sized human tumor metastases.

Identification of oligomeric domains within dermatan sulfate chains using differential enzymic treatments, derivatization with 2-aminoacridone and capillary electrophoresis

Galactosaminoglycans, i.e. dermatan sulfate (DS) and chondroitin sulfate, are linear heteropolysaccharides consisting of repeating disaccharide units of L-iduronic acid (L-IdoA) or D-glucuronic acid (D-GlcA) residues linked to N-acetyl-galactosamine. High-performance capillary electrophoresis (HPCE or CE) has been successfully used for determining the disaccharide composition of glycosaminoglycans. However, only limited information is available on how to identify oligomeric domains rich in D-GlcA or L-IdoA. The aim of this study was therefore to develop a rapid and accurate CE procedure by which such oligosaccharides can be determined together with the variously sulfated disaccharides. Isolated dermatan sulfates of human origin were separately digested with chondroitinases ABC, AC and B and the enzymic products were derivatized with 2-aminoacridone. CE analysis of these products was performed using a phosphate buffer, pH 3.0, and reversed polarity at 30 kV. The derivatization enabled their detection with laser-induced fluorescence (LIF) and UV at 260 nm at much higher sensitivity than the detection of nonderivatized delta-saccharides at 232 nm and therefore components undetectable at 232 nm were nicely detected after derivatization. Except for delta-disaccharides, altogether five distinct oligosaccharides with differences in charge density were identified. Depending on the lyase that produced these oligomers, information on the presence of L-IdoA- or D-GlcA-containing domains within the DS chain and the sulfation pattern of these oligomeric domains was obtained. This CE method could also be useful in studying the functional oligomeric domains in galactosaminoglycan chains.

Importance of GlcUAbeta1-3GalNAc(4S,6S) in chondroitin sulfate E for t-PA- and u-PA-mediated Glu-plasminogen activation

Chondroitin sulfate E (CSE) markedly enhanced plasminogen activation by tissue plasminogen activators (t-PAs) and urinary plasminogen activator (u-PA) in vitro; in the presence of 10 microg/ml of CSE, the potentiation factors of single chain of t-PA, two chain of t-PA and u-PA were 400, 140 and 130, respectively. Though the potentiation activity of CSE gradually decreased when it was depolymerized by chondroitinase ABC, the specific disaccharide from CSE still showed significant activity. Glycosaminoglycan (GAG) from sea cucumber, which possesses a very similar core structure to CSE, but has additional sulfated fucose branches exhibit very weak activity. These results suggested that the minimal structural requirement in CSE to enhance plasminogen activation by plasminogen activators is GlcUAbeta1-3GalNAc(4S,6S) and that additional branching sugars abolish the activity.

Low-molecular-weight dextran derivatives (f-CMDB) enter the nucleus and are better cell-growth inhibitors compared with parent CMDB polymers

Carboxymethyldextrans-benzylamide (CMDB) are dextran derivatives that are statistically substituted with carboxymethyl and benzylamide groups. These molecules display a variety of biological effects, one of which is their inhibitory activity against mammary tumor cell growth, both in vitro and in vivo. We and others have previously shown that the effects of CMDB on cell growth are related to their ability to interact with the growth factor FGF-2. The binding modifies the conformation of FGF-2, leading to the suppression of its mitogenic activity. Here, the method previously reported to fragment natural polysaccharide fucans has been applied to CMDB (80,000 g/mol). f-CMDB (fragmented CMDB) of molecular weights from 6000 to 20,000 g/mol were found to be more potent inhibitors of MCF7 mammary tumor cell growth than high-molecular-weight CMDB. Confocal microscopy experiments using CMDB and f-CMDB labeled with the fluorophore DTAF (5-([4,6-dichlorotriazine-2-yl]amino) fluorescein) indicate that only low-molecular-weight f-CMDB penetrate into the nucleus of MCF7 cells. It is thus assumed that the better inhibitory properties demonstrated by f-CMDB, compared with CMDB, are related to their better ability to penetrate the nucleus and interact with nuclear targets, including topoisomerase II. The DNA relaxation properties of the latter are inhibited in vitro by both CMDB and f-CMDB. These findings could help us to develop models of low-molecular-weight oligosaccharide derivatives exhibiting better antiproliferative and antitumor properties.

Urinary excretion of sulfated polysaccharides administered to Wistar rats suggests a renal permselectivity to these polymers based on molecular size

Sulfated polysaccharides were administered to Wistar rats and their elimination from the blood as well as their urinary excretion were evaluated. Sulfated polysaccharides with differences in molecular mass, charge density and molecular structure were obtained from algae, marine invertebrates and vertebrates. A simple methodology based on the metachromatic property of these polysaccharides with 1,9-dimethylmethylene blue was used to estimate their concentration in urine and blood. Renal permselectivity to these macromolecules was based on molecular size, but the upper limit of molecular mass for excretion of a sulfated polysaccharide in urine varies among polymers with different structures. For dextran sulfates the upper limit is approximately 8 kDa. Chondroitin 4- and 6-sulfates were excreted as fragments of approximately 30 kDa, which is smaller than the injected polysaccharide. This suggests that they were degraded enzymatically in vivo. Large synthetic polymers (dextran sulfate > 8 kDa) were not excreted in urine, but slowly disappeared from the blood. Evaluation of their tissue distribution after intravenous administration indicated that these molecules are preferentially accumulated in the kidney.

Compositional and structural alterations of arterial glycosaminoglycans associated with the complications brought about by thalassemia major. A case report

A biochemical analysis of glycosaminoglycans was performed in arteries of a fifteen-year old white male who died of beta thalassemia major. The patient presented the severe clinical complications resulting from hemochromatosis, which was evidenced at autopsy and by histologic examination. The arteries under study comprised the thoracic and abdominal aortas and the iliac and pulmonary arteries, which were compared with the same arteries from normal individuals. Data on total glycosaminoglycan and total collagen, including the determination of the relative contents of the different glycosaminoglycans, suggest an as yet undescribed fibrotic process in the thalassemic arteries. Also altered were the proportions of the disaccharides making up chondroitin sulfate and heparin sulfate. A reduction in the molecular weight of arterial heparin sulfate, presumably with free radical involvement, was also detected. All these changes in the extracellular matrix may be ascribed to the presence of large amounts of iron in the tissue, and as such they should be expected in other disorders with chronic iron overload.

Activity of chondroitin ABC lyase and hyaluronidase on free-radical degraded chondroitin sulfate

High molecular mass-chondroitin sulfate was characterized for M(r), charge density and constituent disaccharides. This glycosaminoglycan was depolymerized by a controlled free-radical process mediated by hydrogen peroxide in the absence or presence of cupric or ferrous ions. Hydrogen peroxide depolymerizes chondroitin sulfate, and the velocity of the reaction increases in the presence of cupric ions and, further, of ferrous ions. Different low molecular mass-chondroitin sulfate fractions were produced and analyzed by high-performance size-exclusion chromatography and polyacrylamide-gel electrophoresis. This last technique strongly supports the hypothesis that the free-radical process proceeds by the destruction of disaccharide units. The treatment of free-radical chondroitin sulfate samples with chondroitinase ABC and testicular hyaluronidase results in a lower capacity of these enzymes to degrade these glycosaminoglycan derivatives with respect to the natural sample. This was confirmed by polyacrylamide-gel electrophoresis and by the time-courses of enzymatic treatment evaluated by spectrophotometric technique (for treatment with chondroitin ABC lyase).

Activity of chondroitin ABC lyase on dermatan sulfate partially degraded by cupric-ion-mediated free-radical treatment

Dermatan sulfate was extracted and purified from bovine intestinal mucosa, pig intestinal mucosa and pigskin. Small differences in M(r), charge density and constituent disaccharides were detected for the three purified natural dermatan sulfates. Bovine intestinal mucosa dermatan sulfate was depolymerized by a controlled free-radical process mediated by cupric ions in the presence of hydrogen peroxide. Different low-molecular-mass dermatan sulfate fractions were produced and analysed by high-performance size-exclusion chromatography and polyacrylamide gel electrophoresis. The results obtained by this last technique strongly support the hypothesis that the free-radical process proceeds essentially via the destruction of disaccharide units. The partial degradation of dermatan sulfates by cupric-ion-mediated free-radical treatment reduces or even eliminates the capacity of chondroitin ABC lyase to depolymerize these derivatives. This was confirmed by polyacrylamide gel electrophoresis and the time curves of enzymatic treatments evaluated by spectrophotometry.