Structural and mechanistic characterization of bifunctional heparan sulfate N-deacetylase-N-sulfotransferase 1.

Heparan sulfate (HS) polysaccharides are major constituents of the extracellular matrix, which are involved in myriad structural and signaling processes. Mature HS polysaccharides contain complex, non-templated patterns of sulfation and epimerization, which mediate interactions with diverse protein partners. Complex HS modifications form around initial clusters of glucosamine-N-sulfate (GlcNS) on nascent polysaccharide chains, but the mechanistic basis underpinning incorporation of GlcNS itself into HS remains unclear. Here, we determine cryo-electron microscopy structures of human N-deacetylase-N-sulfotransferase (NDST)1, the bifunctional enzyme primarily responsible for initial GlcNS modification of HS. Our structures reveal the architecture of both NDST1 deacetylase and sulfotransferase catalytic domains, alongside a non-catalytic N-terminal domain. The two catalytic domains of NDST1 adopt a distinct back-to-back topology that limits direct cooperativity. Binding analyses, aided by activity-modulating nanobodies, suggest that anchoring of the substrate at the sulfotransferase domain initiates the NDST1 catalytic cycle, providing a plausible mechanism for cooperativity despite spatial domain separation. Our data shed light on key determinants of NDST1 activity, and describe tools to probe NDST1 function in vitro and in vivo.

Development of the Reporting Infographics and Visual Abstracts of Comparative studies (RIVA-C) checklist and guide.

People often use infographics (also called visual or graphical abstracts) as a substitute for reading the full text of an article. This is a concern because most infographics do not present sufficient information to interpret the research appropriately and guide wise health decisions. The Reporting Infographics and Visual Abstracts of Comparative studies (RIVA-C) checklist and guide aims to improve the completeness with which research findings of comparative studies are communicated and avoid research findings being misinterpreted if readers do not refer to the full text. The primary audience for the RIVA-C checklist and guide is developers of infographics that summarise comparative studies of health and medical interventions. The need for the RIVA-C checklist and guide was identified by a survey of how people use infographics. Possible checklist items were informed by a systematic review of how infographics report research. We then conducted a two-round, modified Delphi survey of 92 infographic developers/designers, researchers, health professionals and other key stakeholders. The final checklist includes 10 items. Accompanying explanation and both text and graphical examples linked to the items were developed and pilot tested over a 6-month period. The RIVA-C checklist and guide was designed to facilitate the creation of clear, transparent and sufficiently detailed infographics which summarise comparative studies of health and medical interventions. Accurate infographics can ensure research findings are communicated appropriately and not misinterpreted. By capturing the perspectives of a wide range of end users (eg, authors, informatics editors, journal editors, consumers), we are hopeful of rapid endorsement and implementation of RIVA-C.

Education can reassure people with rotator cuff-related shoulder pain: a 3-arm, randomised, online experiment.

ABSTRACT: We aimed to investigate the immediate effect of best practice education (with and without pain science messages) and structure-focused education on reassurance among people with rotator cuff-related shoulder pain. We conducted a 3-arm, parallel-group, randomised experiment. People with rotator cuff-related shoulder pain were randomised (1:1:1) to (1) best practice education (highlights that most shoulder pain is not serious or a good indicator of tissue damage and recommends simple self-management strategies); (2) best practice education plus pain science messages (which attempt to improve understanding of pain); and (3) structure-focused education (highlighting that structural changes are responsible for pain and should be targeted with treatment). Coprimary outcomes were self-reported reassurance that no serious condition is causing their pain and continuing with daily activities is safe. Secondary outcomes measured management intentions, credibility and relevance of the education, and similarity to previous education. Two thousand two hundred thirty-seven participants were randomised and provided primary outcome data. Best practice education increased reassurance that no serious condition is causing their pain (estimated mean effect 0.5 on a 0-10 scale, 95% confidence interval [CI] 0.2-0.7) and continuing with daily activities is safe (0.6, 95% CI 0.3-0.8) compared with structure-focused education . Adding pain science messages to best practice education slightly increased both measures of reassurance (0.2, 95% CI 0.0-0.4). Clinicians treating patients with rotator cuff-related shoulder pain should highlight that most shoulder pain is not serious or a good indicator of tissue damage and recommend simple self-management strategies. The benefit of adding pain science messages is small.

Adding Brief Pain Science or Ergonomics Messages to Guideline Advice Did Not Increase Feelings of Reassurance in People With Acute Low Back Pain: A Randomized Experiment.

OBJECTIVE: To investigate the effects of adding pain science or ergonomics messages to guideline advice on feelings of reassurance and management intentions among people with acute low back pain (LBP). DESIGN: Three-arm parallel-group randomized experiment. METHODS: We recruited people with acute LBP (pain for ≤6 weeks) to participate in an online experiment. Participants were randomized at a 1:1:1 ratio to one of three groups: guideline advice alone or guideline advice with the addition of brief pain science or ergonomics messages. The intervention was delivered via prerecorded videos in all 3 groups. Coprimary outcomes were reassurance that (1) no serious condition is causing LBP and (2) continuing with daily activities is safe. Secondary outcomes were perceived risk of developing chronic pain, management intentions (bed rest, see a health professional, see a specialist, and imaging), credibility, and relevance of the advice in addressing the participant's concerns. RESULTS: Two thousand two hundred ninety-seven responses (99.3% of 2,313 randomized) were analyzed. Adding brief pain science or ergonomics messages to guideline advice did not change reassurance that LBP was not caused by serious disease. The addition of ergonomics advice provided worse reassurance that it is safe to continue with daily activities compared to guideline advice (mean difference [MD], -0.33; 95% CI: 0.13, 0.53). There was no difference between groups on management intentions. CONCLUSION: Adding pain science or ergonomics messages to guideline advice did not increase reassurance or change management intentions in people with acute LBP. Ergonomics messages may lead to reduced feelings of reassurance. J Orthop Sports Phys Ther 2023;53(12)1-11. Epub 26 September 2023. doi:10.2519/jospt.2023.12090.

Analysis of Heparin Samples by Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy in the Solid State.

Heparin is a polydisperse, heterogeneous polysaccharide of the glycosaminoglycan (GAG) class that has found widespread clinical use as a potent anticoagulant and is classified as an essential medicine by the World Health Organization. The importance of rigorous monitoring and quality control of pharmaceutical heparin was highlighted in 2008, when the existing regulatory procedures failed to identify a life-threatening adulteration of pharmaceutical heparin with oversulfated chondroitin sulfate (OSCS). The subsequent contamination crisis resulted in the exploration of alternative approaches for which the use of multidimensional nuclear magnetic resonance (NMR) spectroscopy techniques and multivariate analysis emerged as the gold standard. This procedure is, however, technically demanding and requires access to expensive equipment. An alternative approach, utilizing attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) combined with multivariate analysis, has been developed. The method described enables the differentiation of diverse GAG samples, the classification of samples of distinct species provenance, and the detection of both established heparin contaminants and alien polysaccharides. This methodology has sensitivity comparable to that of NMR and can facilitate the rapid, cost-effective monitoring and analysis of pharmaceutical heparin. It is therefore suitable for future deployment throughout the supply chain.

A sulphated glycosaminoglycan extract from Placopecten magellanicus inhibits the Alzheimer's disease ß-site amyloid precursor protein cleaving enzyme 1 (BACE-1).

The clinically important anticoagulant heparin, a member of the glycosaminoglycan family of carbohydrates that is extracted predominantly from porcine and bovine tissue sources, has previously been shown to inhibit the ß-site amyloid precursor protein cleaving enzyme 1 (BACE-1), a key drug target in Alzheimer's Disease. In addition, heparin has been shown to exert favourable bioactivities through a number of pathophysiological pathways involved in the disease processes of Alzheimer's Disease including inflammation, oxidative stress, tau phosphorylation and amyloid peptide generation. Despite the multi-target potential of heparin as a therapeutic option for Alzheimer's disease, the repurposing of this medically important biomolecule has to-date been precluded by its high anticoagulant potential. An alternative source to mammalian-derived glycosaminoglycans are those extracted from marine environments and these have been shown to display an expanded repertoire of sequence-space and heterogeneity compared to their mammalian counterparts. Furthermore, many marine-derived glycosaminoglycans appear to retain favourable bioactivities, whilst lacking the high anticoagulant potential of their mammalian counterparts. Here we describe a sulphated, marine-derived glycosaminoglycan extract from the Atlantic Sea Scallop, Placopecten magellanicus that displays high inhibitory potential against BACE-1 (IC50 = 4.8 µg.mL-1) combined with low anticoagulant activity; 25-fold less than that of heparin. This extract possesses a more favourable therapeutic profile compared to pharmaceutical heparin of mammalian provenance and is composed of a mixture of heparan sulphate (HS), with a high content of 6-sulphated N-acetyl glucosamine (64%), and chondroitin sulphate.

Evidence for Multiple Binding Modes in the Initial Contact Between SARS-CoV-2 Spike S1 Protein and Cell Surface Glycans.

Infection of host cells by SARS-CoV-2 begins with recognition by the virus S (spike) protein of cell surface heparan sulfate (HS), tethering the virus to the extracellular matrix environment, and causing the subunit S1-RBD to undergo a conformational change into the 'open' conformation. These two events promote the binding of S1-RBD to the angiotensin converting enzyme 2 (ACE2) receptor, a preliminary step toward viral-cell membrane fusion. Combining ligand-based NMR spectroscopy with molecular dynamics, oligosaccharide analogues were used to explore the interactions between S1-RBD of SARS CoV-2 and HS, revealing several low-specificity binding modes and previously unidentified potential sites for the binding of extended HS polysaccharide chains. The evidence for multiple binding modes also suggest that highly specific inhibitors will not be optimal against protein S but, rather, diverse HS-based structures, characterized by high affinity and including multi-valent compounds, may be required.

Synthetic Heparan Sulfate Mimetic Pixatimod (PG545) Potently Inhibits SARS-CoV-2 by Disrupting the Spike-ACE2 Interaction.

Heparan sulfate (HS) is a cell surface polysaccharide recently identified as a coreceptor with the ACE2 protein for the S1 spike protein on SARS-CoV-2 virus, providing a tractable new therapeutic target. Clinically used heparins demonstrate an inhibitory activity but have an anticoagulant activity and are supply-limited, necessitating alternative solutions. Here, we show that synthetic HS mimetic pixatimod (PG545), a cancer drug candidate, binds and destabilizes the SARS-CoV-2 spike protein receptor binding domain and directly inhibits its binding to ACE2, consistent with molecular modeling identification of multiple molecular contacts and overlapping pixatimod and ACE2 binding sites. Assays with multiple clinical isolates of SARS-CoV-2 virus show that pixatimod potently inhibits the infection of monkey Vero E6 cells and physiologically relevant human bronchial epithelial cells at safe therapeutic concentrations. Pixatimod also retained broad potency against variants of concern (VOC) including B.1.1.7 (Alpha), B.1.351 (Beta), B.1.617.2 (Delta), and B.1.1.529 (Omicron). Furthermore, in a K18-hACE2 mouse model, pixatimod significantly reduced SARS-CoV-2 viral titers in the upper respiratory tract and virus-induced weight loss. This demonstration of potent anti-SARS-CoV-2 activity tolerant to emerging mutations establishes proof-of-concept for targeting the HS-Spike protein-ACE2 axis with synthetic HS mimetics and provides a strong rationale for clinical investigation of pixatimod as a potential multimodal therapeutic for COVID-19.

Planning implementation and scale-up of physical activity interventions for people with walking difficulties: study protocol for the process evaluation of the ComeBACK trial.

BACKGROUND: There is currently little evidence of planning for real-world implementation of physical activity interventions. We are undertaking the ComeBACK (Coaching and Exercise for Better Walking) study, a 3-arm hybrid Type 1 randomised controlled trial evaluating a health coaching intervention and a text messaging intervention. We used an implementation planning framework, the PRACTical planning for Implementation and Scale-up (PRACTIS), to guide the process evaluation for the trial. The aim of this paper is to describe the protocol for the process evaluation of the ComeBACK trial using the framework of the PRACTIS guide. METHODS: A mixed methods process evaluation protocol was developed informed by the Medical Research Council (MRC) guidance on process evaluations for complex interventions and the PRACTIS guide. Quantitative data, including participant questionnaires, health coach and administrative logbooks, and website and text message usage data, is being collected over the trial period. Semi-structured interviews and focus groups with trial participants, health coaches and health service stakeholders will explore expectations, factors influencing the delivery of the ComeBACK interventions and potential scalability within existing health services. These data will be mapped against the steps of the PRACTIS guide, with reporting at the level of the individual, provider, organisational and community/systems. Quantitative and qualitative data will elicit potential contextual barriers and facilitators to implementation and scale-up. Quantitative data will be reported descriptively, and qualitative data analysed thematically. DISCUSSION: This process evaluation integrates an evaluation of prospective implementation and scale-up. It is envisaged this will inform barriers and enablers to future delivery, implementation and scale-up of physical activity interventions. To our knowledge, this is the first paper to describe the application of PRACTIS to guide the process evaluation of physical activity interventions. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry ( ANZCTR ) Registration date: 10/12/2018.

The Hyperlipidaemic Drug Fenofibrate Significantly Reduces Infection by SARS-CoV-2 in Cell Culture Models.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic has caused a significant number of fatalities and worldwide disruption. To identify drugs to repurpose to treat SARS-CoV-2 infections, we established a screen to measure the dimerization of angiotensin-converting enzyme 2 (ACE2), the primary receptor for the virus. This screen identified fenofibric acid, the active metabolite of fenofibrate. Fenofibric acid also destabilized the receptor-binding domain (RBD) of the viral spike protein and inhibited RBD binding to ACE2 in enzyme-linked immunosorbent assay (ELISA) and whole cell-binding assays. Fenofibrate and fenofibric acid were tested by two independent laboratories measuring infection of cultured Vero cells using two different SARS-CoV-2 isolates. In both settings at drug concentrations, which are clinically achievable, fenofibrate and fenofibric acid reduced viral infection by up to 70%. Together with its extensive history of clinical use and its relatively good safety profile, this study identifies fenofibrate as a potential therapeutic agent requiring an urgent clinical evaluation to treat SARS-CoV-2 infection.

Evidence of a putative glycosaminoglycan binding site on the glycosylated SARS-CoV-2 spike protein N-terminal domain.

SARS-CoV-2 has rapidly spread throughout the world's population since its initial discovery in 2019. The virus infects cells via a glycosylated spike protein located on its surface. The protein primarily binds to the angiotensin-converting enzyme-2 (ACE2) receptor, using glycosaminoglycans (GAGs) as co-receptors. Here, we performed bioinformatics and molecular dynamics simulations of the spike protein to investigate the existence of additional GAG binding sites on the receptor-binding domain (RBD), separate from previously reported heparin-binding sites. A putative GAG binding site in the N-terminal domain (NTD) of the protein was identified, encompassing residues 245-246. We hypothesized that GAGs of a sufficient length might bridge the gap between this site and the PRRARS furin cleavage site, including the mutation S247R. Docking studies using GlycoTorch Vina and subsequent MD simulations of the spike trimer in the presence of dodecasaccharides of the GAGs heparin and heparan sulfate supported this possibility. The heparan sulfate chain bridged the gap, binding the furin cleavage site and S247R. In contrast, the heparin chain bound the furin cleavage site and surrounding glycosylation structures, but not S247R. These findings identify a site in the spike protein that favors heparan sulfate binding that may be particularly pertinent for a better understanding of the recent UK and South African strains. This will also assist in future targeted therapy programs that could include repurposing clinical heparan sulfate mimetics.

Glycosaminoglycans from Litopenaeus vannamei Inhibit the Alzheimer's Disease ß Secretase, BACE1.

Only palliative therapeutic options exist for the treatment of Alzheimer's Disease; no new successful drug candidates have been developed in over 15 years. The widely used clinical anticoagulant heparin has been reported to exert beneficial effects through multiple pathophysiological pathways involved in the aetiology of Alzheimer's Disease, for example, amyloid peptide production and clearance, tau phosphorylation, inflammation and oxidative stress. Despite the therapeutic potential of heparin as a multi-target drug for Alzheimer's disease, the repurposing of pharmaceutical heparin is proscribed owing to the potent anticoagulant activity of this drug. Here, a heterogenous non-anticoagulant glycosaminoglycan extract, obtained from the shrimp Litopenaeus vannamei, was found to inhibit the key neuronal ß-secretase, BACE1, displaying a more favorable therapeutic ratio compared to pharmaceutical heparin when anticoagulant activity is considered.

Unfractionated heparin inhibits live wild type SARS-CoV-2 cell infectivity at therapeutically relevant concentrations.

BACKGROUND AND PURPOSE: Currently, there are no licensed vaccines and limited antivirals for the treatment of COVID-19. Heparin (delivered systemically) is currently used to treat anticoagulant anomalies in COVID-19 patients. Additionally, in the United Kingdom, Brazil and Australia, nebulised unfractionated heparin (UFH) is being trialled in COVID-19 patients as a potential treatment. A systematic comparison of the potential antiviral effect of various heparin preparations on live wild type SARS-CoV-2, in vitro, is needed. EXPERIMENTAL APPROACH: Seven different heparin preparations including UFH and low MW heparins (LMWH) of porcine or bovine origin were screened for antiviral activity against live SARS-CoV-2 (Australia/VIC01/2020) using a plaque inhibition assay with Vero E6 cells. Interaction of heparin with spike protein RBD was studied using differential scanning fluorimetry and the inhibition of RBD binding to human ACE2 protein using elisa assays was examined. KEY RESULTS: All the UFH preparations had potent antiviral effects, with IC50 values ranging between 25 and 41 µg·ml-1 , whereas LMWHs were less inhibitory by ~150-fold (IC50 range 3.4-7.8 mg·ml-1 ). Mechanistically, we observed that heparin binds and destabilizes the RBD protein and furthermore, we show heparin directly inhibits the binding of RBD to the human ACE2 protein receptor. CONCLUSION AND IMPLICATIONS: This comparison of clinically relevant heparins shows that UFH has significantly stronger SARS-CoV-2 antiviral activity compared to LMWHs. UFH acts to directly inhibit binding of spike protein to the human ACE2 protein receptor. Overall, the data strongly support further clinical investigation of UFH as a potential treatment for patients with COVID-19.

Heparin Inhibits Cellular Invasion by SARS-CoV-2: Structural Dependence of the Interaction of the Spike S1 Receptor-Binding Domain with Heparin.

The dependence of development and homeostasis in animals on the interaction of hundreds of extracellular regulatory proteins with the peri- and extracellular glycosaminoglycan heparan sulfate (HS) is exploited by many microbial pathogens as a means of adherence and invasion. Heparin, a widely used anticoagulant drug, is structurally similar to HS and is a common experimental proxy. Exogenous heparin prevents infection by a range of viruses, including S-associated coronavirus isolate HSR1. Here, we show that heparin inhibits severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) invasion of Vero cells by up to 80% at doses achievable through prophylaxis and, particularly relevant, within the range deliverable by nebulisation. Surface plasmon resonance and circular dichroism spectroscopy demonstrate that heparin and enoxaparin, a low-molecular-weight heparin which is a clinical anticoagulant, bind and induce a conformational change in the spike (S1) protein receptor-binding domain (S1 RBD) of SARS-CoV-2. A library of heparin derivatives and size-defined fragments were used to probe the structural basis of this interaction. Binding to the RBD is more strongly dependent on the presence of 2-O or 6-O sulfate groups than on N-sulfation and a hexasaccharide is the minimum size required for secondary structural changes to be induced in the RBD. It is likely that inhibition of viral infection arises from an overlap between the binding sites of heparin/HS on S1 RBD and that of the angiotensin-converting enzyme 2. The results suggest a route for the rapid development of a first-line therapeutic by repurposing heparin and its derivatives as antiviral agents against SARS-CoV-2 and other members of the Coronaviridae.

Molecular Changes in Dengue Envelope Protein Domain III upon Interaction with Glycosaminoglycans.

Dengue fever is a rapidly emerging vector-borne viral disease with a growing global burden of approximately 390 million new infections per annum. The Dengue virus (DENV) is a flavivirus spread by female mosquitos of the aedes genus, but the mechanism of viral endocytosis is poorly understood at a molecular level, preventing the development of effective transmission blocking vaccines (TBVs). Recently, glycosaminoglycans (GAGs) have been identified as playing a role during initial viral attachment through interaction with the third domain of the viral envelope protein (EDIII). Here, we report a systematic study investigating the effect of a range of biologically relevant GAGs on the structure and oligomeric state of recombinantly generated EDIII. We provide novel in situ biophysical evidence that heparin and chondroitin sulphate C induce conformational changes in EDIII at the secondary structure level. Furthermore, we report the ability of chondroitin sulphate C to bind EDIII and induce higher-order dynamic molecular changes at the tertiary and quaternary structure levels which are dependent on pH, GAG species, and the GAG sulphation state. Lastly, we conducted ab initio modelling of Small Angle Neutron Scattering (SANS) data to visualise the induced oligomeric state of EDIII caused by interaction with chondroitin sulphate C, which may aid in TBV development.

Inhibition of BACE1, the ß-secretase implicated in Alzheimer's disease, by a chondroitin sulfate extract from Sardina pilchardus.

The pharmaceutical and anticoagulant agent heparin, a member of the glycosaminoglycan family of carbohydrates, has previously been identified as a potent inhibitor of a key Alzheimer's disease drug target, the primary neuronal ß-secretase, ß-site amyloid precursor protein cleaving enzyme 1 (BACE1). The anticoagulant activity of heparin has, however, precluded the repurposing of this widely used pharmaceutical as an Alzheimer's disease therapeutic. Here, a glycosaminoglycan extract, composed predominantly of 4-sulfated chondroitin sulfate, has been isolated from Sardina pilchardus, which possess the ability to inhibit BACE1 (IC50 [half maximal inhibitory concentration] = 4.8 µg/mL), while displaying highly attenuated anticoagulant activities (activated partial thromboplastin time EC50 [median effective concentration] = 403.8 µg/mL, prothrombin time EC50 = 1.3 mg/mL). The marine-derived, chondroitin sulfate extract destabilizes BACE1, determined via differential scanning fluorimetry (ΔTm -5°C), to a similar extent as heparin, suggesting that BACE1 inhibition by glycosaminoglycans may occur through a common mode of action, which may assist in the screening of glycan-based BACE1 inhibitors for Alzheimer's disease.

Tools for the Quality Control of Pharmaceutical Heparin.

Heparin is a vital pharmaceutical anticoagulant drug and remains one of the few naturally sourced pharmaceutical agents used clinically. Heparin possesses a structural order with up to four levels of complexity. These levels are subject to change based on the animal or even tissue sources that they are extracted from, while higher levels are believed to be entirely dynamic and a product of their surrounding environments, including bound proteins and associated cations. In 2008, heparin sources were subject to a major contamination with a deadly compound-an over-sulphated chondroitin sulphate polysaccharide-that resulted in excess of 100 deaths within North America alone. In consideration of this, an arsenal of methods to screen for heparin contamination have been applied, based primarily on the detection of over-sulphated chondroitin sulphate. The targeted nature of these screening methods, for this specific contaminant, may leave contamination by other entities poorly protected against, but novel approaches, including library-based chemometric analysis in concert with a variety of spectroscopic methods, could be of great importance in combating future, potential threats.

Challenges to assessing professional identity in medical students: a tale of two measures.

Background: Professional identity formation (PIF), a foundational process in becoming a physician, includes establishment of values, moral principles, and self-awareness. The purpose of this report is to examine challenges in establishing the validity of measures of identity fusion as one facet of PIF. Method: Utilizing the modern approach of validity as a unitary concept, the authors generated six hypotheses to examine the evidence for the construct validity of the scores of Physician Professional Identity (PPI) and Identity Integration (IdIn), considering relationships of these measures with each other, year of training and data from a larger survey. Results: Responses from 3473 students at 8 medical schools revealed a weak association between the measures with distributions varying by cohort. PPI had a stronger relationship to cohort and IdIn was moderately associated with students' attitudes relevant to social media use. Responses were independent of response format and evidence supported the interpretation of scores for IdIn as indications of integration of identity. Discussion : Sufficient evidence was found to suggest that these measures assess aspects of PIF. Use of these measures as part of a multidimensional, longitudinal approach to refining understanding of the construct of PIF and developing effective assessment strategies.

A Glycosaminoglycan Extract from Portunus pelagicus Inhibits BACE1, the ß Secretase Implicated in Alzheimer's Disease.

Therapeutic options for Alzheimer's disease, the most common form of dementia, are currently restricted to palliative treatments. The glycosaminoglycan heparin, widely used as a clinical anticoagulant, has previously been shown to inhibit the Alzheimer's disease-relevant ß-secretase 1 (BACE1). Despite this, the deployment of pharmaceutical heparin for the treatment of Alzheimer's disease is largely precluded by its potent anticoagulant activity. Furthermore, ongoing concerns regarding the use of mammalian-sourced heparins, primarily due to prion diseases and religious beliefs hinder the deployment of alternative heparin-based therapeutics. A marine-derived, heparan sulphate-containing glycosaminoglycan extract, isolated from the crab Portunus pelagicus, was identified to inhibit human BACE1 with comparable bioactivity to that of mammalian heparin (IC50 = 1.85 µg mL-1 (R2 = 0.94) and 2.43 µg mL-1 (R2 = 0.93), respectively), while possessing highly attenuated anticoagulant activities. The results from several structural techniques suggest that the interactions between BACE1 and the extract from P. pelagicus are complex and distinct from those of heparin.

Marine glycosaminoglycan-like carbohydrates as potential drug candidates for infectious disease.

Glycosaminoglycans (GAGs), present in the extracellular matrix, are exploited by numerous, distinct microbes for cellular attachment, adhesion, invasion and evasion of the host immune system. Glycosaminoglycans, including the widely used, clinical anticoagulant heparin and semi-synthetic analogues thereof, have been reported to inhibit and disrupt interactions between microbial proteins and carbohydrates present on the surface of host cells. However, the anticoagulant properties of unmodified, pharmaceutical heparin preparations preclude their capabilities as therapeutics for infectious disease states. Here, unique Glycosaminoglycan-like saccharides from various, distinct marine species are reported for their potential use as therapeutics against infectious diseases; many of which possess highly attenuated anticoagulant activities, while retaining significant antimicrobial properties.