Preparation of low molecular weight heparins from bovine and ovine heparins using nitrous acid degradation

Quality control, safety assessment and preparation approaches of low molecular weight heparin

Low Molecular Weight Heparins (LMWHs) are well-established for use in the prevention and treatment of thrombotic diseases, and as a substitute for unfractionated heparin (UFH) due to their predictable pharmacokinetics and subcutaneous bioavailability. LMWHs are produced by various depolymerization methods from UFH, resulting in heterogeneous compounds with similar biochemical and pharmacological properties. However, the delicate supply chain of UFH and potential contamination from animal sources require new manufacturing approaches for LMWHs. Various LMWH preparation methods are emerging, such as chemical synthesis, enzymatic or chemical depolymerization and chemoenzymatic synthesis. To establish the sameness of active ingredients in both innovator and generic LMWH products, the Food and Drug Administration has implemented a stringent scientific method of equivalence based on physicochemical properties, heparin source material and depolymerization techniques, disaccharide composition and oligosaccharide mapping, biological and biochemical properties, and in vivo pharmacodynamic profiles. In this review, we discuss currently available LMWHs, potential manufacturing methods, and recent progress for manufacturing quality control of these LMWHs.

Enzymatic construction of a library of even- and odd-numbered heparosan oligosaccharides and their N-sulfonated derivatives

Low-molecular-weight heparins (LMWHs), especially the specific-sized heparin oligosaccharides, are attractive for the therapeutic applications, while their synthesis remains challenging. In the present study, unsaturated even-numbered heparosan oligosaccharides were firstly prepared by cleaving high-molecular-weight heparosan using recombinant heparinase III (HepIII). The conversion rates of the unsaturated disaccharides, tetrasaccharides, hexasaccharides, octasaccharides, and decasaccharides were 33.9 %, 47.9 %, 78.7 %, 71.8 %, and 53.4 %, respectively. After processing the aforementioned heparosan oligosaccharides with the Δ4,5 unsaturated glycuronidase, saturated odd-numbered heparosan trisaccharides, pentasaccharides, heptasaccharides, and nonasaccharides were produced. It was observed that among them, the pentasaccharides were the smallest units of saturated odd-numbered oligosaccharides recognized by HepIII. These oligosaccharides were further catalyzed with bifunctional heparan sulfate N-deacetylase/N-sulfotransferase (NDST) under optimized reaction conditions. It was found that the tetrasaccharide was defined as the smallest recognition unit for NDST, obtaining the N-sulfonated heparosan tetrasaccharides, pentasaccharides, and hexasaccharides with a single sulfonate group, as well as N-sulfonated heparosan heptasaccharides, octasaccharides, and nonasaccharides with multiple sulfonate groups. These results provide an easy pathway for constructing a library of specific-sized N-sulfonated heparosan oligosaccharides that can be used as the substrates for the enzymatic synthesis of LMWHs and heparin oligosaccharides, shedding new light on the substrate preference of NDST.

Non-Anticoagulant Activities of Low Molecular Weight Heparins-A Review

Low molecular weight heparins (LMWHs) are derived from heparin through chemical or enzymatic cleavage with an average molecular weight (Mw) of 2000-8000 Da. They exhibit more selective activities and advantages over heparin, causing fewer side effects, such as bleeding and heparin-induced thrombocytopenia. Due to different preparation methods, LMWHs have diverse structures and extensive biological activities. In this review, we describe the basic preparation methods in this field and compare the main principles and advantages of these specific methods in detail. Importantly, we focus on the non-anticoagulant pharmacological effects of LMWHs and their conjugates, such as preventing glycocalyx shedding, anti-inflammatory, antiviral infection, anti-fibrosis, inhibiting angiogenesis, inhibiting cell adhesion and improving endothelial function. LMWHs are effective in various diseases at the animal level, including cancer, some viral diseases, fibrotic diseases, and obstetric diseases. Finally, we briefly summarize their usage and potential applications in the clinic to promote the development and utilization of LMWHs.

Scientific considerations in the regulatory approval of generic (or biosimilar) version of enoxaparin sodium - A lifesaving carbohydrate polymer

Enoxaparin sodium (Clexane®/Klexane®/Lovenox®) is one amongst the few drugs that have assumed a central role as drug of treatment and/or prevention against thromboembolic complications during COVID-19. The increase in demand resulting in many generic (or biosimilar) versions entering the market has increased the risks of quality and safety (including immunogenicity) related issues. Under the circumstances, development of stringent regulatory approaches has received much attention as investigation of new drug delivery systems for improved therapeutic activity. As one of the measures to increase quality testing and ensure uninterrupted supply of this life-saving drug globally, determination of enoxaparin molecular weight (MW) has been added in the United States Pharmacopoeia (USP) monograph for enoxaparin sodium. In addition, the presence of a unique 1,6-anhydro-ring structure at the reducing end of about 15-25% of the poly (oligo) saccharide chains of the generic (or biosimilar) product has been set as a mandatory requirement. This article presents an overview of the scientific considerations in the quality manufacturing and testing of the generic (or biosimilar) enoxaparin for regulatory review and approval. In certain cases of strong analytical similarity (structural and functional), abandonment of in vivo testing in animals and humans represents a major advancement in the approval of generic (or biosimilar) version of innovator enoxaparin sodium (lovenox®, injections).

MsPHep: An online application for low molecular weight heparin rapid characterization based on liquid chromatography-tandem mass spectrometry

Low-molecular-weight heparins (LMWHs) are important anticoagulants widely used in clinic. Since they are comprised of complex and heterogenous glycan chains, liquid chromatography-tandem mass spectrometry (LC-MS) is commonly used for structural analysis and quality control of LMWHs to ensure their safety and efficacy. Yet, the structural complexity arising from the parent heparin macromolecules, as well as the different depolymerization methods used for preparing LMWHs, makes processing and assigning the LC-MS data of LWMHs very tedious and challenging. We therefore developed, and here report, an open-source and easy-to-use web application, MsPHep, to facilitate the LMWH analysis based on LC-MS data. MsPHep is compatible with various LMWHs and chromatographic separation methods. With the HepQual function, MsPHep is capable of annotating both the LMWH compound and its isotopic distribution from mass spectra. Moreover, the HepQuant function enables automatic quantification of LMWH compositions without prior knowledge or any database generation. To demonstrate the reliability and system stability of MsPHep, we tested various types of LMWHs that were analyzed with different chromatographic methods coupled to MS. The results show that MsPHep has its own advantages compared to another public tool GlycReSoft for LMWH analysis, and it is available online under an open-source license at https://ngrc-glycan.shinyapps.io/MsPHep.

Pharmacology of Heparin and Related Drugs: An Update

Heparin has been used extensively as an antithrombotic and anticoagulant for close to 100 years. This anticoagulant activity is attributed mainly to the pentasaccharide sequence, which potentiates the inhibitory action of antithrombin, a major inhibitor of the coagulation cascade. More recently it has been elucidated that heparin exhibits anti-inflammatory effect via interference of the formation of neutrophil extracellular traps and this may also contribute to heparin's antithrombotic activity. This illustrates that heparin interacts with a broad range of biomolecules, exerting both anticoagulant and nonanticoagulant actions. Since our previous review, there has been an increased interest in these nonanticoagulant effects of heparin, with the beneficial role in patients infected with SARS2-coronavirus a highly topical example. This article provides an update on our previous review with more recent developments and observations made for these novel uses of heparin and an overview of the development status of heparin-based drugs. SIGNIFICANCE STATEMENT: This state-of-the-art review covers recent developments in the use of heparin and heparin-like materials as anticoagulant, now including immunothrombosis observations, and as nonanticoagulant including a role in the treatment of SARS-coronavirus and inflammatory conditions.

[Advances in heparin structural analysis by chromatography technologies]

Heparin （Hp） is the most widely used anticoagulant drug in the clinics， with an annual global output of over 10 billion dollars. Hp， a member of the glycosaminoglycans （GAGs）， is prepared from porcine intestinal mucosa via extraction， separation， and purification. Hp is a linear polysaccharide with repeating disaccharide units. Low-molecular-weight heparins （LMWHs） are depolymerized from Hp via chemical or enzymatic degradation. Compared with Hp， LMWHs exhibit less bleeding side effect， milder immunogenicity， and higher bioavailability when injected subcutaneously. In general， Hps， including LMWHs， are high complex drugs with large molecular weights （MWs）， inhomogeneous MW distributions， and structural heterogeneity， including different degrees and locations of sulfonation， and unique residues generated from different production processes. Thus， developing efficient analytical methods to elucidate the structures of Hps and characterize or quantitate their properties is extremely challenging. Unfortunately， this problem limits their quality control， production optimization， clinical safety monitoring， and new applications. Research has constantly sought to elucidate the complicated structures of Hp drugs. Among the structural analysis and quality control methods of Hp currently available， chromatographic methods are the most widely studied and used. However， no literature thoroughly summarizes the specific applications of chromatographic methods in the structural analysis， manufacturing process， and quality control of Hp drugs. This paper systematically organizes and describes recent research progresses of the chromatographic methods used to analyze Hp drugs， including the identification and composition of monosaccharides， disaccharides， oligosaccharides， and polysaccharides. The applications， innovations， and limitations of these chromatographic methods are also summarized in this review. The insights obtained in this study will help production and quality control personnel， as well as drug researchers， obtain a deeper understanding of the complex structures of Hp drugs. This paper also provides a comprehensive reference for the structural analysis and quality control of Hps， proposes ideas for the development of new quality control methods， and lays a strong foundation for the in-depth structural elucidation of Hp drugs.

Identification of pheophorbide a as an inhibitor of receptor for advanced glycation end products in Mallotus japonicus

Accumulation of advanced glycation end products (AGEs) plays an important role in diabetes, immunoinflammation, and cardiovascular and neurodegenerative diseases. Since AGEs mediate their pathological effects through interaction with receptor for AGEs (RAGE), RAGE antagonists would provide a useful therapeutic option for various health disorders. Therefore, in this study, we aimed to identify phytochemicals that would inhibit binding of AGEs to RAGE, which may help develop new drug leads and/or nutraceuticals for AGE-RAGE-related diseases. On screening ethanol extracts obtained from 700 plant materials collected in Myanmar, we found that the ethanol extract from the leaves of Mallotus philippensis inhibited the binding of AGEs to RAGE. We also found that the leaves of M. japonicus, which belongs to the same genera and distributes abundantly in Japan, exhibited the inhibitory activity similar to M. philippensis. Activity-guided fractionation and LC/MS analysis of the ethanol extract of M. japonicus helped identify pheophorbide a (PPBa) as a major component in the active fraction, along with some other pheophorbide derivatives. PPBa exhibited potent inhibitory activity against AGE-RAGE binding, with an IC₅₀ value (0.102 μM) comparable to that of dalteparin (0.084 μM). PPBa may be a valuable natural product for use as a therapeutic agent and/or a nutraceutical against various health complications arising from activation of the AGE-RAGE axis.

Hydrolytic Degradation of Heparin in Acidic Environments: Nuclear Magnetic Resonance Reveals Details of Selective Desulfation

Heparin is a complex glycosaminoglycan, derived mainly from pig mucosa, used therapeutically for its anticoagulant activity. Yet, owing largely to the chain complexity, the progressive effects of environmental conditions on heparin structure have not been fully described. A systematic study of the influence of acidic hydrolysis on heparin chain length and substitution has therefore been conducted. Changes in the sulfation pattern, monitored via 2D NMR, revealed initial de-N-sulfation of the molecule (pH 1/ 40 °C) and unexpectedly identified the secondary sulfate of iduronate as more labile than the 6-O-sulfate of glucosamine residues under these conditions (pH 1/ 60 °C). Additionally, the loss of sulfate groups, rather than depolymerization, accounted for most of the reduction in molecular weight. This provides an alternative route to producing partially 2-O-de-sulfated heparin derivatives that avoids using conventional basic conditions and may be of value in the optimization of processes associated with the production of heparin pharmaceuticals.

Advances in the preparation and synthesis of heparin and related products

Heparin is a naturally occurring glycosaminoglycan from livestock, principally porcine intestine, and is clinically used as an anticoagulant drug. A limitation to heparin production is that it depends on a single animal species and potential problems have been associated with animal-derived heparin. The contamination crisis in 2008 led to a search for new animal sources and the investigation of non-animal sources of heparin. Over the past 5 years, new animal sources, chemical, and chemoenzymatic methods have been introduced to prepare heparin-based drugs. In this review, we describe advances in the preparation and synthesis of heparin and related products.

Non-Anticoagulant Low Molecular Weight Heparins for Pharmaceutical Applications

Heparin is a polypharmacological agent with anticoagulant activity. Periodate oxidation of the nonsulfated glucuronic acid residue results in non-anticoagulant heparin derivative (NACH) of reduced molecular weight. Similar treatment of a low molecular weight heparin, dalteparin, also removes its anticoagulant activity, affording a second heparin derivative (D-NACH). A full structural characterization of these two derivatives reveals their structural differences. SPR studies display their ability to bind to several important heparin-binding proteins, suggesting potential new therapeutic applications.

Chemometric analysis of porcine, bovine and ovine heparins

Heparin is a polysaccharide anticoagulant drug isolated from animal tissues. There have been concerns on the safety and security of the heparin supply chain since 2007-8 when a contamination crisis led to its disruption. The current study applies a suite of modern analytical techniques to porcine, bovine and ovine intestinal mucosal heparins. These techniques include structural analysis by nuclear magnetic resonance spectrometry, disaccharide compositional analysis, bottom-up analysis of tetrasaccharides corresponding to heparin's antithrombin III binding site. Chemometric analysis was then applied to understand how these structural differences to predict the animal/tissue source of heparin and to help detect blending of heparins from various sources.

Comparative Pharmacokinetic Profile of 3 Batches of Ovine Low-Molecular-Weight Heparin and 1 Batch of Branded Enoxaparin

Although pharmaceutical grade heparin is obtained almost exclusively from porcine intestinal mucosa, there is interest in diversifying heparin sourcing to address potential supply shortages and economically motivated adulteration. Since ovine-derived heparin is structurally similar to porcine heparin, it is expected that ovine-derived low-molecular-weight heparin (LMWH) will be comparable to porcine-derived LMWH. This study compared the pharmacokinetic (PK) behavior of 3 batches of ovine LMWH with that of enoxaparin in nonhuman primates. Blood samples were collected prior to and at 2, 4, and 6 hours post-administration of a 1 mg/kg subcutaneous dose of LMWH. Circulating drug concentrations determined using anti-Xa and anti-thrombin assays were used to calculate values for PK parameters. Tissue factor pathway inhibitor (TFPI) levels were measured by enzyme-linked immunosorbent assay. The ovine LMWHs tested met pharmacopoeial potency and molecular weight distribution requirements for enoxaparin. In the post-administration samples, comparable levels of branded enoxaparin and ovine enoxaparin were observed using anti-Xa and anti-thrombin assays, with the concentration versus time curves being nearly superimposable. Consistent with this similarity, no significant differences were observed between PK parameters calculated for branded enoxaparin and ovine LMWH. The TFPI levels returned to baseline levels by 6 hours in ovine LMWH-treated animals but remained slightly elevated in animals treated with branded enoxaparin. It is concluded that the pharmacokinetics of ovine enoxaparin were not only comparable between different batches but also similar to the branded product. Thus, LMWH prepared from ovine mucosal heparin is comparable to its porcine-derived counterpart.