Determination of the molecular weight of low-molecular-weight heparins by using high-pressure size exclusion chromatography on line with a triple detector array and conventional methods

Molecular architecture and platelet-activating properties of small immune complexes assembled on heparin and platelet factor 4

Heparin-induced thrombocytopenia (HIT) is an adverse reaction to heparin leading to a reduction in circulating platelets with an increased risk of thrombosis. It is precipitated by polymerized immune complexes consisting of pathogenic antibodies that recognize a small chemokine platelet factor 4 (PF4) bound to heparin. Characterization of these immune complexes is extremely challenging due to the enormous structural heterogeneity of such macromolecular assemblies and their constituents. Native mass spectrometry demonstrates that up to three PF4 tetramers can be assembled on a heparin chain, consistent with the molecular modeling studies showing facile polyanion wrapping along the polycationic belt on the PF4 surface. Although these assemblies can accommodate a maximum of only two antibodies, the resulting immune complexes are capable of platelet activation despite their modest size. Taken together, these studies provide further insight into molecular mechanisms of HIT and other immune disorders where anti-PF4 antibodies play a central role.

Polysaccharides: potential bioactive macromolecules for Alzheimer's disease

Alzheimer's disease (AD) is one of the leading causes of death and disability. AD is a devastating disease that has caused an overwhelming burden. However, no disease-modified treatment was discovered. The approval of sodium oligomannate (GV-971) in mild-moderate AD patients has attracted great attention to investigate the role of saccharides in AD. Therefore, summarizing and explaining the role of saccharides in AD is urgent and promising. Recent studies showed that polysaccharides (PSs) potentially benefit AD in vitro and in vivo. PSs could alleviate the pathological damage and improve cognitive symptoms via (1) antagonizing the toxicity of abnormal amyloid-beta and tau proteins; (2) attenuating oxidative stress and proinflammation; (3) rebuilding neuroplasticity. PSs exhibit one-multiple pathological hits of AD. However, a thorough chemical investigation is needed for further study.

Molecular architecture and platelet-activating properties of small immune complexes assembled on intact heparin and their possible involvement in heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is an adverse reaction to heparin leading to a reduction in circulating platelets with an increased risk of thrombosis. It is precipitated by polymerized immune complexes consisting of pathogenic antibodies that recognize a small chemokine platelet factor 4 (PF4) bound to heparin, which trigger platelet activation and a hypercoagulable state. Characterization of these immune complexes is extremely challenging due to the enormous structural heterogeneity of such macromolecular assemblies and their constituents (especially heparin). We use native mass spectrometry to characterize small immune complexes formed by PF4, heparin and monoclonal HIT-specific antibodies. Up to three PF4 tetramers can be assembled on a heparin chain, consistent with the results of molecular modeling studies showing facile polyanion wrapping along the polycationic belt on the PF4 surface. Although these assemblies can accommodate a maximum of only two antibodies, the resulting immune complexes are capable of platelet activation despite their modest size. Taken together, these studies provide further insight into molecular mechanisms of HIT and other immune disorders where anti-PF4 antibodies play a central role.

Molecular weight determination of low molecular weight hyaluronic acid and chondroitin sulfate by gel permeation chromatography

Low molecular weight (LWM) hyaluronic acid (HA) and chondroitin sulfate (CS) have a wide range of applications. To determine their molecular weight (MW), we developed a gel permeation chromatography (GPC) method, which is calibrated based on serrated peaks in the chromatograms. MW calibrants were obtained from the enzymolysis of HA and CS using hyaluronidase. The identical structure of calibrants and samples ensured the soundness of the method. The highest confidence MWs were up to 14,454 and 14,605 for HA and CS, respectively, and the standard curves showed very high correlation coefficients. Thanks to the changeless relationship between MW and its contribution to the GPC integral, the second calibration curves could be derived via one GPC column, also embodied correlation coefficients of >0.9999. The discrepancies of MW values were minuscule, and the measurement of a sample could be conducted in <30 min. The accuracy of the method was verified using LWM heparins, and the measured Mw values showed a 1.2 %-2.0 % error relative to pharmacopeia results. The MW results obtained for LWM-HA and LWM-CS samples were also consistent with the results obtained by multiangle laser light scattering. The method was also verified be able to measure the very low MWs.

Heparin-Superparamagnetic Iron Oxide Nanoparticles for Theranostic Applications

In this study, superparamagnetic iron oxide nanoparticles (SPIONs) were engineered with an organic coating composed of low molecular weight heparin (LMWH) and bovine serum albumin (BSA), providing heparin-based nanoparticle systems (LMWH@SPIONs). The purpose was to merge the properties of the heparin skeleton and an inorganic core to build up a targeted theranostic nanosystem, which was eventually enhanced by loading a chemotherapeutic agent. Iron oxide cores were prepared via the co-precipitation of iron salts in an alkaline environment and oleic acid (OA) capping. Dopamine (DA) was covalently linked to BSA and LMWH by amide linkages via carbodiimide coupling. The following ligand exchange reaction between the DA-BSA/DA-LMWH and OA was conducted in a biphasic system composed of water and hexane, affording LMWH@SPIONs stabilized in water by polystyrene sulfonate (PSS). Their size and morphology were investigated via dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. The LMWH@SPIONs’ cytotoxicity was tested, showing marginal or no toxicity for samples prepared with PSS at concentrations of 50 µg/mL. Their inhibitory activity on the heparanase enzyme was measured, showing an effective inhibition at concentrations comparable to G4000 (N-desulfo-N-acetyl heparin, a non-anticoagulant and antiheparanase heparin derivative; Roneparstat). The LMWH@SPION encapsulation of paclitaxel (PTX) enhanced the antitumor effect of this chemotherapeutic on breast cancer cells, likely due to an improved internalization of the nanoformulated drug with respect to the free molecule. Lastly, time-domain NMR (TD-NMR) experiments were conducted on LMWH@SPIONs obtaining relaxivity values within the same order of magnitude as currently used commercial contrast agents.

Recent advances in qualitative and quantitative analysis of polysaccharides in natural medicines: A critical review

Polysaccharides from natural medicines, being safe and effective natural mixtures, show great potential to be developed into botanical drugs. However, there is yet one polysaccharide-based case that has fulfilled the Botanical Guidance definition of a botanical drug product. One of the reasons is the analytical methods commonly used for qualitative and quantitative analysis of polysaccharides fall far behind the quality control criteria of botanical drugs. Here we systemically reviewed the recent advances in analytical methods. A critical evaluation of the strength and weaknesses of these methods was provided, together with possible solutions to the difficulties. Mass spectrometry with or without robust chromatographic separation was increasingly employed. And scientists have made significant progress in simplifying polysaccharide quantification by depolymerizing it into oligosaccharides. This oligosaccharides-based strategy is promising for qualitative and quantitative analysis of polysaccharides. And continuous efforts are still needed to develop a standardized quality control method that is specific, accurate, repeatable, and applicable for analyzing individual components in natural medicine formulas.

Pentosan polysulfate inhibits attachment and infection by SARS-CoV-2 in vitro: insights into structural requirements for binding

Two years since the outbreak of the novel coronavirus SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) pandemic, there remain few clinically effective drugs to complement vaccines. One is the anticoagulant, heparin, which in 2004 was found able to inhibit invasion of SARS-CoV (CoV-1) and which has been employed during the current pandemic to prevent thromboembolic complications and moderate potentially damaging inflammation. Heparin has also been shown experimentally to inhibit SARS-CoV-2 attachment and infection in susceptible cells. At high therapeutic doses however, heparin increases the risk of bleeding and prolonged use can cause heparin-induced thrombocytopenia, a serious side effect. One alternative, with structural similarities to heparin, is the plant-derived, semi-synthetic polysaccharide, pentosan polysulfate (PPS). PPS is an established drug for the oral treatment of interstitial cystitis, is well-tolerated, and exhibits weaker anticoagulant effects than heparin. In an established Vero cell model, PPS and its fractions of varying molecular weights inhibited invasion by SARS-CoV-2. Intact PPS and its size-defined fractions were characterized by molecular weight distribution and chemical structure using nuclear magnetic resonance spectroscopy and liquid chromatography–mass spectrometry, then employed to explore the structural basis of interactions with SARS-CoV-2 spike protein receptor-binding domain (S1 RBD) and the inhibition of Vero cell invasion. PPS was as effective as unfractionated heparin, but more effective in inhibiting cell infection than low-molecular-weight heparin (on a weight/volume basis). Isothermal titration calorimetry and viral plaque-forming assays demonstrated size-dependent binding to S1 RBD and inhibition of Vero cell invasion, suggesting the potential application of PPS as a novel inhibitor of SARS-CoV-2 infection.

Purification of chitosanases produced by Bacillus toyonensis CCT 7899 and functional oligosaccharides production

Chitooligosaccharides (COS) have a great potential to be used by pharmaceutical industry due to their many biological activities. The use of enzymes to produce them is very advantageous, however it still faces many challenges, such as discovering new strains capable to produce enzymes that are able to generate bioactive oligosaccharides. In the present study a purification protein protocol was performed to purify chitosanases produced by Bacillus toyonensis CCT 7899 for further chitosan hydrolysis. The produced chitooligosaccharides were characterized by mass spectroscopy (MS) and their antiedematogenic effect was investigated through carrageenan-induced paw edema model. The animals were treated previously to inflammation by intragastric route with COS at 30, 300 and 600 mg/kg. The purification protocol showed a good performance for the chitosanases purification using 0.20 M NaCl solution to elute it, with a 9.54-fold purification factor. The treatment with COS promoted a decrease of paw edema at all evaluated times and the AUC0-4h, proving that COS produced showed activity in acute inflammation like commercial anti-inflammatory Dexamethasone (corticosteroid). Therefore, the strategy used to purification was successfully applied and it was possible to generate bioactive oligosaccharides with potential pharmacological use.

Protamine Sulfate Neutralization Profile of Various Dosages of Bovine, Ovine and Porcine UFHs and Their Depolymerized Derivatives in Non-Human Primates

INTRODUCTION

Currently used unfractionated heparins (UFHs) and low molecular weight heparins (LMWHs) are derived from porcine intestinal mucosa. However, heparins have also been manufactured from tissues of other mammalian species such as cow (Bovine) and sheep (Ovine). Protamine sulphate (PS) is an effective inhibitor of heparin and is used clinically to neutralize both LMWH and UFH. In this study, we determined the PS neutralization profile of these agents in non-human primate model using anti-Xa and anti-IIa methods.

MATERIAL AND METHODS

UFHs obtained from bovine, ovine and porcine mucosal tissues and their respective depolymerized LMWHs were administered at both, gravimetric (0.5 mg/kg) and potency adjusted (100 U/kg) dosages regimen intravenously to individual groups of primates in cross over studies. PS was administered at a fixed dosage and the relative neutralization of these anticoagulants was measured utilizing amidolytic anti-Xa and anti-IIa methods.

RESULTS

These studies have demonstrated that, the equi-gravimetric dosages of BMH, PMH and OMH have comparable PS neutralization profiles. At potency adjusted dosages, all UFHs were completely neutralized by PS. Although comparable, the LMWHs were not fully neutralized by PS in both the anti-Xa and anti-IIa assays. PS was more efficient in neutralizing the anti-IIa effects of LMWHs.

CONCLUSION

Heparins of diverse origins showed comparable neutralization profiles by PS in the amidolytic anti-Xa and anti-IIa assays.

Preparation of Low Molecular Weight Heparin from a Remodeled Bovine Intestinal Heparin

Bovine intestinal heparins are structurally distinct from porcine intestinal heparins and exhibit lower specific anticoagulant activity (units/mg). The reduced content of N-sulfo, 3-O-sulfo glucosamine, the central and critical residue in heparin's antithrombin III binding site, is responsible for bovine intestinal heparin's reduced activity. Previous studies demonstrate that treatment of bovine intestinal heparin with 3-O-sulfotransferase in the presence of 3'-phosphoadenosine-5'-phosphosulfate afforded remodeled bovine heparin with an enhanced activity reaching the United States Pharmacopeia's requirements. Starting from this remodeled bovine intestinal heparin, we report the preparation of a bovine intestinal low molecular weight heparin having the same structural properties and anti-factor IIa and anti-factor Xa activities of Enoxaparin. Moreover, this bovine intestinal heparin-derived "Enoxaparin" showed comparable platelet factor-4 binding affinity, suggesting that it should exhibit similarly low levels of heparin induced thrombocytopeneia, HIT.

Advanced delivery strategies facilitating oral absorption of heparins

Heparins show great anticoagulant effect with few side effects, and are administered by subcutaneous or intravenous route in clinics. To improve patient compliance, oral administration is an alternative route. Nonetheless, oral administration of heparins still faces enormous challenges due to the multiple obstacles. This review briefly analyzes a series of barriers ranging from poorly physicochemical properties of heparins, to harsh biological barriers including gastrointestinal degradation and pre-systemic metabolism. Moreover, several approaches have been developed to overcome these obstacles, such as improving stability of heparins in the gastrointestinal tract, enhancing the intestinal epithelia permeability and facilitating lymphatic delivery of heparins. Overall, this review aims to provide insights concerning advanced delivery strategies facilitating oral absorption of heparins.

Comparative Pharmacological Profiles of Various Bovine, Ovine, and Porcine Heparins

Unfractionated heparin is the first anticoagulant drug and has been successfully used clinically for over 80 years. Heparin and its analogues are used during surgery and dialysis and are often used to coat indwelling catheters and other devices where the vascular system is exposed. Most of the heparins used clinically are derived from porcine intestinal mucosa. However, heparins have also been manufactured from tissues of other mammalian species such as cows and sheep. Recently there have been attempts to generate bioengineered heparin in order to overcome contamination and antigenicity problems. Currently there are some concerns about the shortage of the porcine heparins as they are widely used in the manufacturing of the low-molecular-weight heparins. Moreover, due to cultural and religious reasons in some countries, alternative sources of heparins are needed. The Food and Drug Administration and other regulatory agencies have considered alternative sourcing of heparin for potential substitution of porcine heparin and are currently reviewing this matter. Numerous studies are ongoing to understand the structure-activity relationships of these various heparins. In this article, heparins from different animal sources were studied to determine the extent of biosimilarity between them. For these investigations, 10 batches each of bovine mucosal heparin (BMH), ovine mucosal heparin (OMH), and porcine mucosal heparin (PMH) were studied. These studies have demonstrated that OMH and PMH have comparable anticoagulant and antiproteases activities. However, BMH exhibited somewhat a lower potency compared to OMH and PMH in functional assays.

Size distribution and chain conformation of six different fucoidans using size-exclusion chromatography with multiple detection

Fucoidans represent an intriguing class of fucose-containing sulfated polysaccharides. The biological activities of these polysaccharides are related to their compositional and structural parameters, whereby their degree of sulfation, as well as molecular weight (MW) distribution and chain conformation play important roles. Modern NMR and mass spectrometry techniques allow elucidating details of the glycan structure, but not the structure of the whole molecules in their native state. Accordingly, the knowledge about the latter of the fucoidans is currently still limited. Contrary to traditional MW determination by SEC with column calibration, SEC with triple detection provides not only the absolute Mw, but can also give information on additional molecule characteristics. In the present study, we used this method to compare six fucoidans extracted from Fucus vesiculosus (FV), F. serratus (FS), F. evanescens (FE), Dictyosiphon foeniculaceus (DF), Laminaria digitata (LD), and Saccharina latissima (SL) concerning their molar mass (Mw, Mn, Mp, dispersity) and size (rms radius, Rh) characteristics and distribution as well as their chain conformation in solution. The tested fucoidans displayed considerable structural diversity including large differences in their MW profiles and showed to be heterogeneously composed. Fuc-FV and Fuc-SL showed the broadest MW distributions, those from Fuc-FE and Fuc-DF the narrowest ones. Most of the fucoidan fractions (except for Fuc-DF) turned out to exist as expanded flexible chains in PBS solution. The conformation data suggest branched structures with partly long side chains. The knowledge obtained by this study is useful for further fractionation and structural characterization as well as the interpretation of the bioactivity differences between the various fucoidans.

In-depth structural characterization of pentosan polysulfate sodium complex drug using orthogonal analytical tools

Rapid advances have been made in developing analytical technologies for characterization of highly heterogeneous active ingredients of complex drugs, such as pentosan polysulfate (PPS), active ingredient of the drug Elmiron®, approved by the Food and Drug Administration and marketed in the United States to treat interstitial cystitis. PPS sulfated polysaccharides comprise of a repeat unit of β(1-4)-D-xylopyranoses randomly substituted by 4-O-methyl-glucopyranosyluronic acid. To define the critical quality attributes (CQAs) of such a complex drug, it is critical to develop an approach that integrates data from orthogonal analytical methodologies. Here, we developed an approach integrating diverse analytical tools including gel permeation chromatography, LC/ESI-MS and NMR to measure CQAs of PPS. The proposed mathematical framework integrates the data from these diverse analytical methods as function of PPS chain length and building blocks. Our approach would facilitate in establishing a scientific foundation for comparative characterization of drug products with complex active ingredients.

Effects of heparin and derivatives on podocytes: An in vitro functional and morphological evaluation

Unfractionated heparin (UFH) and low molecular heparin derivatives (LMWH) display numerous biological properties in addition to their anticoagulant effects. However, due to the physicochemical heterogeneity of these drugs, a better understanding concerning their effects on human cells is clearly needed. Considering that heparins are mainly excreted by the kidney, we focused our attention on the effect of UFH and LMWH on human podocytes by functional and morphological/phenotypic in vitro analyses. We demonstrated that these products differentially modulate the permeability of podocyte monolayer to albumin. The functional perturbations observed were correlated to significant cellular morphological and cytoskeletal changes, as well as a decrease in the expression of proteins involved in podocyte adherence to the extracellular matrix or intercellular interactions. This point confirms that UFH and the different LMWHs exert specific effects on podocyte permeability and underlines the need of in vitro tests to evaluate new biological nonanticoagulant properties of LMWH.

The Inhibition of Polysialyltranseferase ST8SiaIV Through Heparin Binding to Polysialyltransferase Domain (PSTD)

BACKGROUND

The polysialic acid (polySia) is a unique carbohydrate polymer produced on the surface Of Neuronal Cell Adhesion Molecule (NCAM) in a number of cancer cells, and strongly correlates with the migration and invasion of tumor cells and with aggressive, metastatic disease and poor clinical prognosis in the clinic. Its synthesis is catalyzed by two polysialyltransferases (polySTs), ST8SiaIV (PST) and ST8SiaII (STX). Selective inhibition of polySTs, therefore, presents a therapeutic opportunity to inhibit tumor invasion and metastasis due to NCAM polysialylation. Heparin has been found to be effective in inhibiting the ST8Sia IV activity, but no clear molecular rationale. It has been found that polysialyltransferase domain (PSTD) in polyST plays a significant role in influencing polyST activity, and thus it is critical for NCAM polysialylation based on the previous studies.

OBJECTIVE

To determine whether the three different types of heparin (unfractionated hepain (UFH), low molecular heparin (LMWH) and heparin tetrasaccharide (DP4)) is bound to the PSTD; and if so, what are the critical residues of the PSTD for these binding complexes?

METHODS

Fluorescence quenching analysis, the Circular Dichroism (CD) spectroscopy, and NMR spectroscopy were used to determine and analyze interactions of PSTD-UFH, PSTD-LMWH, and PSTD-DP4.

RESULTS

The fluorescence quenching analysis indicates that the PSTD-UFH binding is the strongest and the PSTD-DP4 binding is the weakest among these three types of the binding; the CD spectra showed that mainly the PSTD-heparin interactions caused a reduction in signal intensity but not marked decrease in α-helix content; the NMR data of the PSTD-DP4 and the PSTDLMWH interactions showed that the different types of heparin shared 12 common binding sites at N247, V251, R252, T253, S257, R265, Y267, W268, L269, V273, I275, and K276, which were mainly distributed in the long α-helix of the PSTD and the short 3-residue loop of the C-terminal PSTD. In addition, three residues K246, K250 and A254 were bound to the LMWH, but not to DP4. This suggests that the PSTD-LMWH binding is stronger than the PSTD-DP4 binding, and the LMWH is a more effective inhibitor than DP4.

CONCLUSION

The findings in the present study demonstrate that PSTD domain is a potential target of heparin and may provide new insights into the molecular rationale of heparin-inhibiting NCAM polysialylation.

Sequencing of Side-Chain Liquid Crystalline Copolymers by Matrix-Assisted Laser Desorption/Ionization Tandem Mass Spectrometry

Polyether based side-chain liquid crystalline (SCLC) copolymers with distinct microstructures were prepared using living anionic polymerization techniques. The composition, end groups, purity, and sequence of the resulting copolymers were elucidated by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and tandem mass spectrometry (MS/MS). MALDI-MS analysis confirmed the presence of (CH₃)₃CO– and –H end groups at the initiating (α) and terminating (ω) chain end, respectively, and allowed determination of the molecular weight distribution and comonomer content of the copolymers. The comonomer positions along the polymer chain were identified by MS/MS, from the fragments formed via C–O and C–C bond cleavages in the polyether backbone. Random and block architectures could readily be distinguished by the contiguous fragment series formed in these reactions. Notably, backbone C–C bond scission was promoted by a radical formed via initial C–O bond cleavage in the mesogenic side chain. This result documents the ability of a properly substituted side chain to induce sequence indicative bond cleavages in the polyether backbone.

Novel method for the determination of average molecular weight of natural polymers based on 2D DOSY NMR and chemometrics: Example of heparin

Apart from the characterization of impurities, the full characterization of heparin and low molecular weight heparin (LMWH) also requires the determination of average molecular weight, which is closely related to the pharmaceutical properties of anticoagulant drugs. To determine average molecular weight of these animal-derived polymer products, partial least squares regression (PLS) was utilized for modelling of diffused-ordered spectroscopy NMR data (DOSY) of a representative set of heparin (n=32) and LMWH (n=30) samples. The same sets of samples were measured by gel permeation chromatography (GPC) to obtain reference data. The application of PLS to the data led to calibration models with root mean square error of prediction of 498Da and 179Da for heparin and LMWH, respectively. The average coefficients of variation (CVs) did not exceed 2.1% excluding sample preparation (by successive measuring one solution, n=5) and 2.5% including sample preparation (by preparing and analyzing separate samples, n=5). An advantage of the method is that the sample after standard 1D NMR characterization can be used for the molecular weight determination without further manipulation. The accuracy of multivariate models is better than the previous results for other matrices employing internal standards. Therefore, DOSY experiment is recommended to be employed for the calculation of molecular weight of heparin products as a complementary measurement to standard 1D NMR quality control. The method can be easily transferred to other matrices as well.

Modernization of Enoxaparin Molecular Weight Determination Using Homogeneous Standards

Enoxaparin is a low-molecular weight heparin used to treat thrombotic disorders. Following the fatal contamination of the heparin supply chain in 2007–2008, the U.S. Pharmacopeia (USP) and U.S. Food and Drug Administration (FDA) have worked extensively to modernize the unfractionated heparin and enoxaparin monographs. As a result, the determination of molecular weight (MW) has been added to the monograph as a measure to strengthen the quality testing and to increase the protection of the global supply of this life-saving drug. The current USP calibrant materials used for enoxaparin MW determination are composed of a mixture of oligosaccharides; however, they are difficult to reproduce as the calibrants have ill-defined structures due to the heterogeneity of the heparin parent material. To address this issue, we describe a promising approach consisting of a predictive computational model built from a library of chemoenzymatically synthesized heparin oligosaccharides for enoxaparin MW determination. Here, we demonstrate that this test can be performed with greater efficiency by coupling synthetic oligosaccharides with the power of computational modeling. Our approach is expected to improve the MW measurement for enoxaparin.

Characterization of Danaparoid Complex Extractive Drug by an Orthogonal Analytical Approach

Danaparoid sodium salt, is the active component of ORGARAN, an anticoagulant and antithrombotic drug constituted of three glycosaminoglycans (GAGs) obtained from porcine intestinal mucosa extracts. Heparan sulfate is the major component, dermatan sulfate and chondroitin sulfate being the minor ones. Currently dermatan sulfate and chondroitin sulfate are quantified by UV detection of their unsaturated disaccharides obtained by enzymatic depolymerization. Due to the complexity of danaparoid biopolymers and the presence of shared components, an orthogonal approach has been applied using more advanced tools and methods. To integrate the analytical profile, 2D heteronuclear single quantum coherence (HSQC) NMR spectroscopy was applied and found effective to identify and quantify GAG component signals as well as those of some process signatures of danaparoid active pharmaceutical ingredient (API) batches. Analyses of components of both API samples and size separated fractions proceeded through the determination and distribution of the molecular weight (Mw) by high performance size exclusion chromatographic triple detector array (HP-SEC-TDA), chain mapping by LC/MS, and mono- (¹H and ¹³C) and bi-dimensional (HSQC) NMR spectroscopy. Finally, large scale chromatographic isolation and depolymerization of each GAG followed by LC/MS and 2D-NMR analysis, allowed the sequences to be defined and components to be evaluated of each GAG including oxidized residues of hexosamines and uronic acids at the reducing ends.

Structural Characterization of the Low-Molecular-Weight Heparin Dalteparin by Combining Different Analytical Strategies

A number of low molecular weight heparin (LMWH) products are available for clinical use and although all share a similar mechanism of action, they are classified as distinct drugs because of the different depolymerisation processes of the native heparin resulting in substantial pharmacokinetic and pharmacodynamics differences. While enoxaparin has been extensively investigated, little information is available regarding the LMWH dalteparin. The present study is focused on the detailed structural characterization of Fragmin^® by LC-MS and NMR applied both to the whole drug and to its enzymatic products. For a more in-depth approach, size homogeneous octasaccharide and decasaccharide components together with their fractions endowed with high or no affinity toward antithrombin were also isolated and their structural profiles characterized. The combination of different analytical strategies here described represents a useful tool for the assessment of batch-to-batch structural variability and for comparative evaluation of structural features of biosimilar products.

Non-anticoagulant effects of low molecular weight heparins in inflammatory disorders: A review

Low molecular weight heparins (LMWHs) are produced by chemical or enzymatic depolymerization of unfractionated heparin (UFH). Besides their well-known anticoagulant effects, LMWHs have also been reported to exhibit numerous anti-inflammatory properties. Previous studies have, however, shown that different production processes result in unique structural characteristics of LMWHs. The structural variations may help explain the different therapeutic spectrums in disease treatment for non-anticoagulant effects. In the present review, we summarize major advances in understanding and exploiting the anti-inflammatory disorder activities of LMWHs, based on mechanistic studies, preclinical experiments and clinical trials. We highlight differences in these activities of commercially available LMWHs produced using different manufacturing processes. We stress the importance of structure-activity relationship (SAR) studies on the non-anticoagulant effects of LMWHs and discuss strategies for exploring new clinical indications.