Antithrombotics from the Sea: Polysaccharides and Beyond

A comprehensive review to assess the potential, health benefits and complications of fucoidan for developing as functional ingredient and nutraceutical

Polysaccharides from seaweeds or macroalgae are garnering significant interest from pharmaceutical and food industries due to their bioactivities and promising therapeutic effects. Among the diverse agal polysaccharides, fucoidan is a well-documented and stands out as a well-researched sulphated heteropolysaccharide found in brown seaweeds. It primarily consists of l-fucose and sulfate ester groups, along with other monosaccharides like xylose, mannose, uronic acid, rhamnose, arabinose, and galactose. Recent scientific investigations have unveiled the formidable inhibitory prowess of fucoidan against SARS-CoV-2, offering a promising avenue for therapeutic intervention in our current landscape. Moreover, fucoidan has demonstrated remarkable abilities in safeguarding the gastrointestinal tract, regulating angiogenesis, mitigating metabolic syndrome, and fortifying bone health. Despite the abundance of studies underscoring fucoidan's potential as a vital component sourced from nature, its exploitation remains constrained by inherent limitations. Thus, the primary objective of this article is to furnish a comprehensive discourse on the structural attributes, health-enhancing properties, safety parameters, and potential toxicity associated with fucoidan. Furthermore, the discourse extends to elucidating the practical applications and developmental prospects of fucoidan as a cornerstone in the realm of functional foods and nutraceuticals.

Marine Pharmacology in 2019-2021: Marine Compounds with Antibacterial, Antidiabetic, Antifungal, Anti-Inflammatory, Antiprotozoal, Antituberculosis and Antiviral Activities; Affecting the Immune and Nervous Systems, and Other Miscellaneous Mechanisms of Action

The current 2019-2021 marine pharmacology literature review provides a continuation of previous reviews covering the period 1998 to 2018. Preclinical marine pharmacology research during 2019-2021 was published by researchers in 42 countries and contributed novel mechanism-of-action pharmacology for 171 structurally characterized marine compounds. The peer-reviewed marine natural product pharmacology literature reported antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral mechanism-of-action studies for 49 compounds, 87 compounds with antidiabetic and anti-inflammatory activities that also affected the immune and nervous system, while another group of 51 compounds demonstrated novel miscellaneous mechanisms of action, which upon further investigation, may contribute to several pharmacological classes. Thus, in 2019-2021, a very active preclinical marine natural product pharmacology pipeline provided novel mechanisms of action as well as new lead chemistry for the clinical marine pharmaceutical pipeline targeting the therapy of several disease categories.

A 70% Ethanol Neorhodomela munita Extract Attenuates RANKL-Induced Osteoclast Activation and H2O2-Induced Osteoblast Apoptosis In Vitro

The rapid aging of the population worldwide presents a significant social and economic challenge, particularly due to osteoporotic fractures, primarily resulting from an imbalance between osteoclast-mediated bone resorption and osteoblast-mediated bone formation. While conventional therapies offer benefits, they also present limitations and a range of adverse effects. This study explores the protective impact of Neorhodomela munita ethanol extract (EN) on osteoporosis by modulating critical pathways in osteoclastogenesis and apoptosis. Raw264.7 cells and Saos-2 cells were used for in vitro osteoclast and osteoblast models, respectively. By utilizing various in vitro methods to detect osteoclast differentiation/activation and osteoblast death, it was demonstrated that the EN's potential to inhibit RANKL induced osteoclast formation and activation by targeting the MAPKs-NFATc1/c-Fos pathway and reducing H2O2-induced cell death through the downregulation of apoptotic signals. This study highlights the potential benefits of EN for osteoporosis and suggests that EN is a promising natural alternative to traditional treatments.

Chemical constituents of the marine-derived fungus Acremonium sp. AN-13

Two new compounds named 3(S)-hydroxy-1-(2,4,5-trihydroxy-3,6- dimethylphenyl)-hex-4E-en-1-one (1) and acremonilactone (2), together with nine known compounds (3-11), were isolated from the fermentation broth of Acremonium sp. associated with marine sediments collected from South China Sea. NMR and HRESIMS spectroscopic analysis elucidated the structure of two new compounds. Compound 2 had characteristic rotary gate shape skeleton with a six-membered lactone. Compounds 1 and 9 showed DPPH radical scavenging activity with inhibition rates of 96.50 and 85.95% at the concentration of 0.5 mg/ml, respectively. Moreover, compounds 4, 6 and 11 showed definite antibacterial activity against Staphylococcus aureus ATCC 6538.

Structural and biofunctional diversity of sulfated polysaccharides from the genus Codium (Bryopsidales, Chlorophyta): A review

It is believed that polysaccharides will become a focal point for future production of food, pharmaceuticals, and materials due to their ubiquitous and renewable nature, as well as their exceptional properties that have been extensively validated in the fields of nutrition, healthcare, and materials. Sulfated polysaccharides derived from seaweed sources have attracted considerable attention owing to their distinctive structures and properties. The genus Codium, represented by the species C. fragile, holds significance as a vital economic green seaweed and serves as a traditional Chinese medicinal herb. To date, the cell walls of the genus Codium have been found to contain at least four types of sulfated polysaccharides, specifically pyruvylated β-d-galactan sulfates, sulfated arabinogalactans, sulfated β-l-arabinans, and sulfated β-d-mannans. These sulfated polysaccharides exhibit diverse biofunctions, including anticoagulant, immune-enhancing, anticancer, antioxidant activities, and drug-carrying capacity. This review explores the structural and biofunctional diversity of sulfated polysaccharides derived from the genus Codium. Additionally, in addressing the impending challenges within the industrialization of these polysaccharides, encompassing concerns regarding scale-up production and quality control, we outline potential strategies to address these challenges from the perspectives of raw materials, extraction processes, purification technologies, and methods for quality control.

Antiviral Activity of Kappaphycus alvarezii Seaweed against ZIKV

INTRODUCTION

Zika virus (ZIKV) is a flavivirus transmitted through the bites of infected Aedes mosquitoes. These viruses can also be transmitted through sexual contact, vertical transmission, and possibly transfusion. Most cases are asymptomatic, but symptoms can include rash, conjunctivitis, fever, and arthralgia, which are characteristic of other arboviruses. Zika infection can lead to complications such as microcephaly, miscarriage, brain abnormalities, and Guillain-Barré syndrome (GBS).

OBJECTIVE

The aim is to determine the inhibitory potential of the algae Kappaphycus alvarezii (K. alvarezii) on ZIKV replication.

METHODOLOGY

Cytotoxicity experiments were performed using Vero cells to determine the CC50, and ZIKV replication inhibition assays (ATCC® VR-1839™) were conducted to determine the EC50. The mechanism of action was also studied to assess any synergistic effect with Ribavirin.

RESULTS

K. alvarezii demonstrated low toxicity with a CC50 of 423 μg/mL and a potent effect on ZIKV replication with an EC50 of 0.65 μg/mL and a Selectivity Index (SI) of 651, indicating the extract's safety. Virucidal effect assays were carried out to evaluate the possible mechanism of action, and the compound addition time was studied, showing the potential to delay the treatment of infected cells by up to 6 hours. A potential synergistic effect was observed when K. alvarezii extract was combined with suboptimal concentrations of Ribavirin, resulting in 99% inhibition of viral replication.

CONCLUSION

Our data demonstrate the significant potential of K. alvarezii extract and highlight the need for further studies to investigate its mechanism of action. We propose this extract as a potential anti-Zika compound.

Understanding Macroalgae: A Comprehensive Exploration of Nutraceutical, Pharmaceutical, and Omics Dimensions

Driven by a surge in global interest in natural products, macroalgae or seaweed, has emerged as a prime source for nutraceuticals and pharmaceutical applications. Characterized by remarkable genetic diversity and a crucial role in marine ecosystems, these organisms offer not only substantial nutritional value in proteins, fibers, vitamins, and minerals, but also a diverse array of bioactive molecules with promising pharmaceutical properties. Furthermore, macroalgae produce approximately 80% of the oxygen in the atmosphere, highlighting their ecological significance. The unique combination of nutritional and bioactive attributes positions macroalgae as an ideal resource for food and medicine in various regions worldwide. This comprehensive review consolidates the latest advancements in the field, elucidating the potential applications of macroalgae in developing nutraceuticals and therapeutics. The review emphasizes the pivotal role of omics approaches in deepening our understanding of macroalgae's physiological and molecular characteristics. By highlighting the importance of omics, this review also advocates for continued exploration and utilization of these extraordinary marine organisms in diverse domains, including drug discovery, functional foods, and other industrial applications. The multifaceted potential of macroalgae warrants further research and development to unlock their full benefits and contribute to advancing global health and sustainable industries.

Chondroitin Sulfate/Dermatan Sulfate Hybrid Chains from Swim Bladder: Isolation, Structural Analysis, and Anticoagulant Activity

Glycosaminoglycans (GAGs) with unique structures from marine animals show intriguing pharmacological activities and negligible biological risks, providing more options for us to explore safer agents. The swim bladder is a tonic food and folk medicine, and its GAGs show good anticoagulant activity. In this study, two GAGs, CMG-1.0 and GMG-1.0, were extracted and isolated from the swim bladder of Cynoscion microlepidotus and Gadus morhua. The physicochemical properties, precise structural characteristics, and anticoagulant activities of these GAGs were determined for the first time. The analysis results of the CMG-1.0 and GMG-1.0 showed that they were chondroitin sulfate (CS)/dermatan sulfate (DS) hybrid chains with molecular weights of 109.3 kDa and 123.1 kDa, respectively. They were mainly composed of the repeating disaccharide unit of -{IdoA-α1,3-GalNAc4S-β1,4-}- (DS-A). The DS-B disaccharide unit of -{IdoA2S-α1,3-GalNAc4S-β1,4-}- also existed in both CMG-1.0 and GMG-1.0. CMG-1.0 had a higher proportion of CS-O disaccharide unit -{-GlcA-β1,3-GalNAc-β1,4-}- but a lower proportion of CS-E disaccharide unit -{-GlcA-β1,3-GalNAc4S6S-β1,4-}- than GMG-1.0. The disaccharide compositions of the GAGs varied in a species-specific manner. Anticoagulant activity assay revealed that both CMG-1.0 and GMG-1.0 had potent anticoagulant activity, which can significantly prolong activated partial thromboplastin time. GMG-1.0 also can prolong the thrombin time. CMG-1.0 showed no intrinsic tenase inhibition activity, while GMG-1.0 can obviously inhibit intrinsic tenase with EC50 of 58 nM. Their significantly different anticoagulant activities may be due to their different disaccharide structural units and proportions. These findings suggested that swim bladder by-products of fish processing of these two marine organisms may be used as a source of anticoagulants.

Glycosaminoglycans from the Starfish Lethasterias fusca: Structures and Influence on Hematopoiesis

Crude anionic polysaccharides extracted from the Pacific starfish Lethasterias fusca were purified by anion-exchange chromatography. The main fraction LF, having MW 14.5 kDa and dispersity 1.28 (data of gel-permeation chromatography), was solvolytically desulfated and giving rise to preparation LF-deS with a structure of dermatan core [→3)-β-d-GalNAc-(1→4)-α-l-IdoA-(1→]n, which was identified according to NMR spectroscopy data. Analysis of the NMR spectra of the parent fraction LF led to identification of the main component as dermatan sulfate LF-Derm →3)-β-d-GalNAc4R-(1→4)-α-l-IdoA2R3S-(1→ (where R was SO3 or H), bearing sulfate groups at O-3 or both at O-2 and O-3 of α-l-iduronic acid, as well as at O-4 of some N-acetyl-d-galactosamine residues. The minor signals in NMR spectra of LF were assigned as resonances of heparinoid LF-Hep composed of the fragments →4)-α-d-GlcNS3S6S-(1→4)-α-l-IdoA2S3S-(1→. The 3-O-sulfated and 2,3-di-O-sulfated iduronic acid residues are very unusual for natural glycosaminoglycans, and further studies are needed to elucidate their possible specific influence on the biological activity of the corresponding polysaccharides. To confirm the presence of these units in LF-Derm and LF-Hep, a series of variously sulfated model 3-aminopropyl iduronosides were synthesized and their NMR spectra were compared with those of the polysaccharides. Preparations LF and LF-deS were studied as stimulators of hematopoiesis in vitro. Surprisingly, it was found that both preparations were active in these tests, and hence, the high level of sulfation is not necessary for hematopoiesis stimulation in this particular case.

Nerolidol Attenuates Cerebral Ischemic Injury in Middle Cerebral Artery Occlusion-Induced Rats via Regulation of Inflammation, Apoptosis, and Oxidative Stress Markers

Background

Cerebral ischemia is a syndrome that occurs due to the restricted flow of oxygen-rich blood to the brain, causing damage to the brain cells. Globally, ischemia ranks second in causing mortality and third in causing disability in stroke patients. Nerolidol is a bioactive compound present in the essential oil of plants with a floral odour. It is a natural sesquiterpene alcohol used in cosmetics, perfumes, and as a food flavouring agent. It also possesses antioxidant, antimicrobial, anti-inflammatory, and anticancer properties.

Materials and Methods

In this study, we assessed the anti-ischemic property of nerolidol in cerebral ischemia-induced mice. Healthy male Wistar rats were induced into cerebral ischemia with middle cerebral artery occlusion (MCAO) and treated with 10 mg and 20 mg nerolidol for 21 days. The brain morphometric, antioxidant, and MMP levels were estimated in the brain tissue of MCAO-performed and nerolidol-treated rats. The cerebral infarct-alleviating potency of nerolidol was analysed by estimating the levels of inflammatory cytokines and apoptotic proteins. It was further confirmed by assessing the levels of COX-2/PGE-2 signalling proteins in brain tissue from MCAO-performed in rats.

Results

Nerolidol significantly reduced the cerebral infarct volume and brain edema via increased antioxidant levels and decreased MMPs. It also decreased the pro-inflammatory cytokines and proapoptotic proteins in brain tissue. The inflammatory signalling proteins NFκB, COX-2, and PGE-2 were significantly decreased in nerolidol-treated MCAO-performed rats, confirming the antiischemic property of nerolidol.

Conclusion

Our results prove nerolidol significantly alleviates cerebral ischemia in rats, and it can be subjected to further trials to be formulated as an anti-ischemic drug.

Antiblood Cell Adhesion of Mussel-Inspired Chondroitin Sulfate- and Caffeic Acid-Modified Polycarbonate Membranes

We fabricated a mussel-inspired hemocompatible polycarbonate membrane (PC) modified by the cross-linking of chondroitin sulfate and caffeic acid polymer using CA-CS via a Schiff base and Michael addition reaction and named it CA-CS-PC. The as-fabricated CA-CS-PC membrane shows excellent hydrophilicity with a water contact angle of 0° and a negative surface charge with a zeta potential of -32 mV. The antiadhesion property of the CA-CS-modified PC membrane was investigated by enzyme-linked immunosorbent assay (ELISA), using human plasma protein fibrinogen adsorption studies, and proved to have excellent antiadhesion properties, because of the lower fibrinogen adsorption. In addition, the CA-CS-PC membrane also shows enhanced hemocompatibility. Finally, blood cell attachment tests of the CA-CS-PC membrane were observed by CLSM and SEM, and the obtained results proved that CA-CS-PC effectively resisted cell adhesion, such as platelets and leucocytes. Therefore, this work disclosed a new way to design a simple and versatile modification of the membrane surface by caffeic acid and chondroitin sulfate and apply it for cell adhesion.

Sulfated Polysaccharides from Macroalgae-A Simple Roadmap for Chemical Characterization

The marine environment presents itself as a treasure chest, full of a vast diversity of organisms yet to be explored. Among these organisms, macroalgae stand out as a major source of natural products due to their nature as primary producers and relevance in the sustainability of marine ecosystems. Sulfated polysaccharides (SPs) are a group of polymers biosynthesized by macroalgae, making up part of their cell wall composition. Such compounds are characterized by the presence of sulfate groups and a great structural diversity among the different classes of macroalgae, providing interesting biotechnological and therapeutical applications. However, due to the high complexity of these macromolecules, their chemical characterization is a huge challenge, driving the use of complementary physicochemical techniques to achieve an accurate structural elucidation. This review compiles the reports (2016-2021) of state-of-the-art methodologies used in the chemical characterization of macroalgae SPs aiming to provide, in a simple way, a key tool for researchers focused on the structural elucidation of these important marine macromolecules.

Polysaccharide-based nanocomposites for biomedical applications: a critical review

Polysaccharides (PSA) have taken specific position among biomaterials for advanced applications in medicine. Nevertheless, poor mechanical properties are known as the main drawback of PSA, which highlights the need for PSA modification. Nanocomposites PSA (NPSA) are a class of biomaterials widely used as biomedical platforms, but despite their importance and worldwide use, they have not been reviewed. Herein, we critically reviewed the application of NPSA by categorizing them into generic and advanced application realms. First, the application of NPSA as drug and gene delivery systems, along with their role in the field as an antibacterial platform and hemostasis agent is discussed. Then, applications of NPSA for skin, bone, nerve, and cartilage tissue engineering are highlighted, followed by cell encapsulation and more critically cancer diagnosis and treatment potentials. In particular, three features of investigations are devoted to cancer therapy, i.e., radiotherapy, immunotherapy, and photothermal therapy, are comprehensively reviewed and discussed. Since this field is at an early stage of maturity, some other aspects such as bioimaging and biosensing are reviewed in order to give an idea of potential applications of NPSA for future developments, providing support for clinical applications. It is well-documented that using nanoparticles/nanomaterials above a critical concentration brings about concerns of toxicity; thus, their effect on cellular interactions would become critical. We compared nanoparticles used in the fabrication of NPSA in terms of toxicity mechanism to shed more light on future challenging aspects of NPSA development. Indeed, the neutralization mechanisms underlying the cytotoxicity of nanomaterials, which are expected to be induced by PSA introduction, should be taken into account for future investigations.

Sulfated Glucuronorhamnoxylan from Capsosiphon fulvescens Ameliorates Osteoporotic Bone Resorption via Inhibition of Osteoclastic Cell Differentiation and Function In Vitro and In Vivo

Excessive osteoclast differentiation and/or bone resorptive function causes a gradual loss of bone, leading to the pathogenesis of bone diseases such as osteoporosis (OP). In this study, a sulfated glucuronorhamnoxylan polysaccharide (designated SPS-CF) of the green alga Capsosiphon fulvescens was evaluated for anti-osteoporotic activity using osteoclastic cells differentiated from RAW264.7 macrophages by receptor activator of NF-κB ligand (RANKL) treatment and ovariectomized (OVX) female mice as a postmenopausal OP model. With negligible cytotoxicity, SPS-CF (50 μg/mL) significantly suppressed tartrate-resistant acid phosphatase (TRAP) activity, actin ring formation, and expression of matrix metalloproteinase 9 (MMP-9), cathepsin K, TRAF6, p-Pyk2, c-Cbl, c-Src, gelsolin, carbonic anhydrase II (CA II), and integrin β3, indicating that SPS-CF inhibits the differentiation and bone resorptive function of osteoclasts. Removal of sulfate groups from SPS-CF abolished its anti-osteoclastogenic activities, demonstrating that sulfate groups are critical for its activity. Oral administration of SPS-CF (400 mg/kg/day) to OVX mice significantly augmented the bone mineral density (BMD) and serum osteoprotegerin (OPG)/RANKL ratio. These results demonstrated that SPS-CF exerts significant anti-osteoporotic activity by dampening osteoclastogenesis and bone resorption via downregulation of TRAF6-c-Src-Pyk2-c-Cbl-gelsolin signaling and augmentation of serum OPG/RANKL ratios in OVX mice, suggesting that SPS-CF can be a novel anti-osteoporotic compound for treating postmenopausal OP.

The anti-atherosclerotic effects of natural polysaccharides: from phenomena to the main mechanisms of action

Polysaccharides (PSs) of plant origin have a variety of biological activities, anti-atherosclerotic including, but their use in atherosclerosis therapy is hindered by insufficient knowledge on the cellular and molecular mechanisms of action. In this review, the influence of several natural PSs on the function of macrophages, viral activity, and macrophage cholesterol metabolism has been discussed considering the tight interplay between these aspects in the pathogenesis of atherosclerosis. The anti-atherosclerotic activities of natural PSs related to other mechanisms have been also explored. Directions for further research of anti-atherosclerotic effects of natural PSs have been outlined, the most promising of which can be nutrigenomic studies.

Fractionation of sulfated galactan from the red alga Botryocladia occidentalis separates its anticoagulant and anti-SARS-CoV-2 properties

Sulfation pattern and molecular weight (MW) play a key role in the biological actions of sulfated glycans. Besides anticoagulant effects, certain sulfated glycans can also exhibit anti-SARS-CoV-2 properties. To develop a more selective antiviral carbohydrate, an efficient strategy to separate these two actions is required. In this work, low MW fractions derived from the red alga Botryocladia occidentalis sulfated galactan (BoSG) were generated, structurally characterized, and tested for activity against SARS-CoV-2 and blood coagulation. The lowest MW fraction was found to be primarily composed of octasaccharides of monosulfated monosaccharides. Unlike heparin or native BoSG, we found that hydrolyzed BoSG products had weak anticoagulant activities as seen by aPTT and inhibitory assays using purified cofactors. In contrast, lower MW BoSG-derivatives retained anti-SARS-CoV-2 activity using SARS-CoV-2 spike (S)-protein pseudotyped lentivirus vector in HEK-293T-hACE2 cells monitored by GFP. Surface plasmon resonance confirmed that longer chains are necessary for BoSG to interact with coagulation cofactors but is not required for interactions with certain S-protein variants. We observed distinct affinities of BoSG derivatives for the S-proteins of different SARS-CoV-2 strains, including WT, N501Y (Alpha), K417T/E484K/N501Y (Gamma), and L542R (Delta) mutants, and stronger affinity for the N501Y-containing variants. Docking of the four possible monosulfated BoSG disaccharides in interactions with the N501Y mutant S-protein predicted potential binding poses of the BoSG constructs and favorable binding in close proximity to the 501Y residue. Our results demonstrate that depolymerization and fractionation of BoSG are an effective strategy to segregate its anticoagulant property from its anti-SARS-CoV-2 action.

Coagulation System Activation for Targeting of COVID-19: Insights into Anticoagulants, Vaccine-Loaded Nanoparticles, and Hypercoagulability in COVID-19 Vaccines

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also known as COVID-19, is currently developing into a rapidly disseminating and an overwhelming worldwide pandemic. In severe COVID-19 cases, hypercoagulability and inflammation are two crucial complications responsible for poor prognosis and mortality. In addition, coagulation system activation and inflammation overlap and produce life-threatening complications, including coagulopathy and cytokine storm, which are associated with overproduction of cytokines and activation of the immune system; they might be a lead cause of organ damage. However, patients with severe COVID-19 who received anticoagulant therapy had lower mortality, especially with elevated D-dimer or fibrin degradation products (FDP). In this regard, the discovery of natural products with anticoagulant potential may help mitigate the numerous side effects of the available synthetic drugs. This review sheds light on blood coagulation and its impact on the complication associated with COVID-19. Furthermore, the sources of natural anticoagulants, the role of nanoparticle formulation in this outbreak, and the prevalence of thrombosis with thrombocytopenia syndrome (TTS) after COVID-19 vaccines are also reviewed. These combined data provide many research ideas related to the possibility of using these anticoagulant agents as a treatment to relieve acute symptoms of COVID-19 infection.

Antithrombotic Activity of Heparinoid G2 and Its Derivatives from the Clam Coelomactra antiquata

Clam heparinoid G2 (60.25 kDa) and its depolymerized derivatives DG1 (24.48 kDa) and DG2 (6.75 kDa) prepared from Coelomactra antiquata have been documented to have excellent fibrinolytic and anticoagulant activity. In this study, to further explore the antithrombotic activity of G2, DG1 and DG2, azure A, sheep plasma, and clot lytic rate assays were used to determine their anticoagulant and thrombolytic activity in vitro. The results indicated that the anticoagulant titer of G2 was approximately 70% that of heparin and the thrombolytic activity of DG2 was greater than G2, DG1, and heparin activities. Moreover, in a carrageenan-induced venous thrombosis model, oral administration of G2 and DG1 each at 20 mg/kg and 40 mg/kg for 7 days significantly reduced blacktail thrombus formation, increased tissue-type plasminogen activator, fibrin degradation products, and D-dimer levels, decreased von Willebrand factor and thromboxane B2 levels, and restored phylum and genus abundance changes of intestinal bacteria. DG2 had no antithrombotic effect. At 20 mg/kg, G2, DG1, and heparin had comparable antithrombotic activities, and DG1 at 40 mg/kg had more muscular antithrombotic activity than G2. Thus, DG1 could be an antithrombotic oral agent owing to its more robust antithrombotic activity and lower molecular weight.

rDromaserpin: A Novel Anti-Hemostatic Serpin, from the Salivary Glands of the Hard Tick Hyalomma dromedarii

Hemostatic disorders are caused either by platelet-related dysfunctions, defective blood coagulation, or by a combination of both, leading to an increased susceptibility to cardiovascular diseases (CVD) and other related illnesses. The unique specificity of anticoagulants from hematophagous arthropods, such as ticks, suggests that tick saliva holds great promise for discovering new treatments for these life-threatening diseases. In this study, we combined in silico and in vitro analyses to characterize the first recombinant serpin, herein called Dromaserpin, from the sialotranscriptome of the Hyalomma dromedarii tick. Our in silico data described Dromaserpin as a secreted protein of ~43 kDa with high similarities to previously characterized inhibitory serpins. The recombinant protein (rDromaserpin) was obtained as a well-structured monomer, which was tested using global blood coagulation and platelet aggregation assays. With this approach, we confirmed rDromaserpin anticoagulant activity as it significantly delayed plasma clotting in activated partial thromboplastin time and thrombin time assays. The profiling of proteolytic activity shows its capacity to inhibit thrombin in the micromolar range (0.2 to 1 μM) and in the presence of heparin this inhibition was clearly increased. It was also able to inhibit Kallikrein, FXIa and slightly FXIIa, with no significant effect on other factors. In addition, the rDromaserpin inhibited thrombin-induced platelet aggregation. Taken together, our data suggest that rDromaserpin deserves to be further investigated as a potential candidate for developing therapeutic compounds targeting disorders related to blood clotting and/or platelet aggregation.

Total Flavonoids of Chuju Decrease Oxidative Stress and Cell Apoptosis in Ischemic Stroke Rats: Network and Experimental Analyses

Background: Pharmacological research results showed that total flavonoids of Chuju (TFCJ) could be used to treat acute myocardial ischemia and myocardial ischemia-reperfusion injury. In this study, we explored the protective effect of TFCJ on ischemic stroke (IS) in the IS rat model. We hypothesized that TFCJ might exert its neuroprotective effects by suppressing apoptosis and oxidative stress that are closely related to PI3K/Akt/mTOR signaling pathway. Method: TFCJ (10, 20, and 40 mg/kg) was administered for 7 days. Rats (260 ± 20 g) were subjected to middle cerebral artery occlusion (MCAO) for 2 h and reperfusion for 24 h. The neuroprotective effect of TFCJ was substantiated in terms of neurological deficits, oxidative stress (superoxide dismutase, glutathione peroxidase, catalase, and malondialdehyde), pathomorphological changes (HE staining and TUNEL staining), and neurobehavioral functions in the rats. Then, we employed network pharmacology to reveal the potential mechanism of TFCJ against IS. Western blot was used to determine the levels of PI3K/AKT/mTOR pathway proteins. The expression of BCL-2, BAX, and cleaved-Caspase-3 was also measured by Western blots and RT-PCR. Results: The histopathological assessment showed that TFCJ reduced MCAO-induced brain damage. Besides, TFCJ exerted a protective role in MCAO rats by alleviating cell apoptosis and oxidative stress. Network pharmacology showed that TFCJ might be used against IS through the PI3K/AKT signaling pathway. TFCJ reduced cell apoptosis and oxidative stress by increasing the level of p-AKT and p-mTOR in MCAO rats, while the effect of TFCJ was significantly reversed when applying LY294002 (PI3k inhibitor). Conclusion: These results indicated that TFCJ might decrease oxidative stress and apoptosis that are closely related to PI3K/Akt/mTOR pathway in IS. TFCJ is a promising authentic traditional Chinese medicine for the management of IS.

A novel anticoagulant peptide discovered from Crassostrea gigas by combining bioinformatics with the enzymolysis strategy: inhibitory kinetics and mechanisms

A novel anticoagulant peptide (IEELEEELEAER) derived from oyster (Crassostrea gigas) was discovered by combining the emerging bioinformatics with the classical enzymolysis approach. The anticoagulant peptide drastically reduced the extrinsic clotting activity (49% residual PT activity) and impaired the intrinsic clotting activity (77% residual PT activity). Consistent with the clotting data, the thrombin peak height reduced to 88.7 from 123.4 nM, and the thrombin generation time delayed to 5.32 from 4.42 min when an extrinsic trigger was applied. The inhibitory kinetics of FXIa, FIXa, FXa, FIIa, and APC in a purified component system rationally explained the reduction of the extrinsic clotting activity and impairment of thrombin generation. Besides the inhibition of FXa and FIIa activity, the activation processes of FX and FII by an intrinsic/extrinsic tenase complex and prothrombinase were also damaged. The anticoagulant activity in the plasma system was the result of comprehensive inhibition of various factors. The research provided a frame for anticoagulant evaluation and inhibitory mechanism of bioactive peptides from food products.

Marine Natural Products and Coronary Artery Disease

Coronary artery disease is the major cause of mortality worldwide, especially in low- and middle-income earners. To not only reduce angina symptoms and exercise-induced ischemia but also prevent cardiovascular events, pharmacological intervention strategies, including antiplatelet drugs, anticoagulant drugs, statins, and other lipid-lowering drugs, and renin-angiotensin-aldosterone system blockers, are conducted. However, the existing drugs for coronary artery disease are incomprehensive and have some adverse reactions. Thus, it is necessary to look for new drug research and development. Marine natural products have been considered a valuable source for drug discovery because of their chemical diversity and biological activities. The experiments and investigations indicated that several marine natural products, such as organic small molecules, polysaccharides, proteins, and bioactive peptides, and lipids were effective for treating coronary artery disease. Here, we particularly discussed the functions and mechanisms of active substances in coronary artery disease, including antiplatelet, anticoagulant, lipid-lowering, anti-inflammatory, and antioxidant activities.

Marine Ingredients for Sensitive Skin: Market Overview

Marine ingredients are a source of new chemical entities with biological action, which is the reason why they have gained relevance in the cosmetic industry. The facial care category is the most relevant in this industry, and within it, the sensitive skin segment occupies a prominent position. This work analyzed the use of marine ingredients in 88 facial cosmetics for sensitive skin from multinational brands, as well as their composition and the scientific evidence that supports their efficacy. Marine ingredients were used in 27% of the cosmetic products for sensitive skin and included the species Laminaria ochroleuca, Ascophyllum nodosum (brown macroalgae), Asparagopsis armata (red macroalgae), and Chlorella vulgaris (microalgae). Carotenoids, polysaccharides, and lipids are the chemical classes highlighted in these preparations. Two ingredients, namely the Ascophyllum nodosum extract and Asparagopsis armata extracts, present clinical evidence supporting their use for sensitive skin. Overall, marine ingredients used in cosmetics for sensitive skin are proposed to reduce skin inflammation and improve the barrier function. Marine-derived preparations constitute promising active ingredients for sensitive skin cosmetic products. Their in-depth study, focusing on the extracted metabolites, randomized placebo-controlled studies including volunteers with sensitive skin, and the use of extraction methods that are more profitable may provide a great opportunity for the cosmetic industry.

A Network Pharmacology Approach for Exploring the Mechanisms of Panax notoginseng Saponins in Ischaemic Stroke

BACKGROUND

Panax notoginseng saponins (PNS) have been deemed effective herb compounds for treating ischaemic stroke (IS) and improving the quality of life of IS patients. This study aimed to investigate the underlying mechanisms of PNS in the treatment of IS based on network pharmacology.

METHODS

PNS were identified from the Traditional Chinese Medicine System Pharmacology (TCMSP) database, and their possible targets were predicted using the PharmMapper database. IS-related targets were identified from the GeneCards database, OMIM database, and DisGeNET database. A herb-compound-target-disease network was constructed using Cytoscape, and protein-protein interaction (PPI) networks were established with STRING. GO enrichment and KEGG pathway analysis were performed using DAVID. The binding of the compounds and key targets was validated by molecular docking studies using AutoDock Vina. The neuroprotective effect of TFCJ was substantiated in terms of oxidative stress (superoxide dismutase, glutathione peroxidase, catalase, and malondialdehyde) and the levels of IGF1/PI3K/Akt pathway proteins.

RESULTS

A total of 375 PNS targets and 5111 IS-related targets were identified. Among these targets, 241 were common to PNS, and IS network analysis showed that MAPK1, AKT1, PIK3R1, SRC, MAPK8, EGFR, IGF1, HRAS, RHOA, and HSP90AA1 are key targets of PNS against IS. Furthermore, GO and KEGG enrichment analysis indicated that PNS probably exert therapeutic effects against IS by regulating many pathways, such as the Ras, oestrogen, FoxO, prolactin, Rap1, PI3K-Akt, insulin, PPAR, and thyroid hormone signalling pathways. Molecular docking studies further corroborated the experimental results.The network pharmacology results were further verified by molecular docking and in vivo experiments.

CONCLUSIONS

The ameliorative effects of PNS against IS were predicted to be associated with the regulation of the IGF1-PI3K-Akt signalling pathway. Ginsenoside Re and ginsenoside Rb1 may play an important role in the treatment of IS.

Marine sulfated polysaccharides as potential antiviral drug candidates to treat Corona Virus disease (COVID-19)

The viral infection caused by SARS-CoV-2 has increased the mortality rate and engaged several adverse effects on the affected individuals. Currently available antiviral drugs have found to be unsuccessful in the treatment of COVID-19 patients. The demand for efficient antiviral drugs has created a huge burden on physicians and health workers. Plasma therapy seems to be less accomplishable due to insufficient donors to donate plasma and low recovery rate from viral infection. Repurposing of antivirals has been evolved as a suitable strategy in the current treatment and preventive measures. The concept of drug repurposing represents new experimental approaches for effective therapeutic benefits. Besides, SARS-CoV-2 exhibits several complications such as lung damage, blood clot formation, respiratory illness and organ failures in most of the patients. Based on the accumulation of data, sulfated marine polysaccharides have exerted successful inhibition of virus entry, attachment and replication with known or unknown possible mechanisms against deadly animal and human viruses so far. Since the virus entry into the host cells is the key process, the prevention of such entry mechanism makes any antiviral strategy effective. Enveloped viruses are more sensitive to polyanions than non-enveloped viruses. Besides, the viral infection caused by RNA virus types embarks severe oxidative stress in the human body that leads to malfunction of tissues and organs. In this context, polysaccharides play a very significant role in providing shielding effect against the virus due to their polyanionic rich features and a molecular weight that hinders their reactive surface glycoproteins. Significantly the functional groups especially sulfate, sulfate pattern and addition, uronic acids, monosaccharides, glycosidic linkage and high molecular weight have greater influence in the antiviral activity. Moreover, they are very good antioxidants that can reduce the free radical generation and provokes intracellular antioxidant enzymes. Additionally, polysaccharides enable a host-virus immune response, activate phagocytosis and stimulate interferon systems. Therefore, polysaccharides can be used as candidate drugs, adjuvants in vaccines or combination with other antivirals, antioxidants and immune-activating nutritional supplements and antiviral materials in healthcare products to prevent SARS-CoV-2 infection.

A Review on Molecular Mechanisms and Patents of Marine-derived Anti-thrombotic Agents

Thrombosis is a condition of major concern worldwide as it is associated with life-threatening diseases related to the cardiovascular system. The condition affects 1 in 1000 adults annually, whereas 1 in 4 dies due to thrombosis, and this increases as the age group increases. The major outcomes are considered to be a recurrence, bleeding due to commercially available anti-coagulants, and deaths. The side effects associated with available anti-thrombotic drugs are a point of concern. Therefore, it is necessary to discover and develop an improvised benefit-risk profile drug, therefore, in search of alternative therapy for the treatment of thrombosis, marine sources have been used as promising treatment agents. They have shown the presence of sulfated fucans/galactans, fibrinolytic proteases, diterpenes, glycosaminoglycan, glycoside, peptides, amino acids, sterols, polysaccharides, polyphenols, vitamins, and minerals. Out of these marine sources, many chemicals were found to have anti-thrombotic activities. This review focuses on the recent discovery of anti-thrombotic agents obtained from marine algae, sponges, mussels, and sea cucumber, along with their mechanism of action and patents on its extraction process, preparation methods, and their applications. Further, the article concludes with the author's insight related to marine drugs, which have a promising future.

Fucosylated Chondroitin Sulfates from the Sea Cucumbers Paracaudina chilensis and Holothuria hilla: Structures and Anticoagulant Activity

Fucosylated chondroitin sulfates (FCSs) PC and HH were isolated from the sea cucumbers Paracaudina chilensis and Holothuria hilla, respectively. The purification of the polysaccharides was carried out by anion-exchange chromatography on a DEAE-Sephacel column. The structural characterization of the polysaccharides was performed in terms of monosaccharide and sulfate content, as well as using a series of nondestructive NMR spectroscopic methods. Both polysaccharides were shown to contain a chondroitin core [→3)-β-d-GalNAc (N-acethyl galactosamine)-(1→4)-β-d-GlcA (glucuronic acid)-(1→]_n, bearing sulfated fucosyl branches at O-3 of every GlcA residue in the chain. These fucosyl residues were different in their pattern of sulfation: PC contained Fuc2S4S and Fuc4S in a ratio of 2:1, whereas HH included Fuc2S4S, Fuc3S4S, and Fuc4S in a ratio of 1.5:1:1. Moreover, some GalNAc residues in HH were found to contain an unusual disaccharide branch Fuc4S-(1→2)-Fuc3S4S-(1→ at O-6. Sulfated GalNAc4S6S and GalNAc4S units were found in a ratio of 3:2 in PC and 2:1 in HH. Both polysaccharides demonstrated significant anticoagulant activity in a clotting time assay, which is connected with the ability of these FCSs to potentiate the inhibition of thrombin and factor Xa in the presence of anti-thrombin III (ATIII) and with the direct inhibition of thrombin in the absence of any cofactors.

Marine Antithrombotics

Thrombosis remains a prime reason of mortality worldwide. With the available antithrombotic drugs, bleeding remains the major downside of current treatments. This raises a clinical concern for all patients undergoing antithrombotic therapy. Novel antithrombotics from marine sources offer a promising therapeutic alternative to this pathology. However, for any potential new molecule to be introduced as a real alternative to existing drugs, the exhibition of comparable anticoagulant potential with minimal off-target effects must be achieved. The relevance of marine antithrombotics, particularly sulfated polysaccharides, is largely due to their unique mechanisms of action and lack of bleeding. There have been many investigations in the field and, in recent years, results have confirmed the role of potential marine molecules as alternative antithrombotics. Nonetheless, further clinical studies are required. This review covers the core of the data available so far regarding the science of marine molecules with potential medical applications to treat thrombosis. After a general discussion about the major biochemical steps involved in this pathology, we discuss the key structural and biomedical aspects of marine molecules of both low and high molecular weight endowed with antithrombotic/anticoagulant properties.

Therapeutic Uses of Red Macroalgae

Red Seaweed “Rhodophyta” are an important group of macroalgae that include approximately 7000 species. They are a rich source of structurally diverse bioactive constituents, including protein, sulfated polysaccharides, pigments, polyunsaturated fatty acids, vitamins, minerals, and phenolic compounds with nutritional, medical, and industrial importance. Polysaccharides are the main components in the cell wall of red algae and represent about 40–50% of the dry weight, which are extensively utilized in industry and pharmaceutical compounds, due to their thickening and gelling properties. The hydrocolloids galactans carrageenans and agars are the main red seaweed cell wall polysaccharides, which had broad-spectrum therapeutic characters. Generally, the chemical contents of seaweed are different according to the algal species, growth stage, environment, and external conditions, e.g., the temperature of the water, light intensity, nutrient concentrations in the ecosystem. Economically, they can be recommended as a substitute source for natural ingredients that contribute to a broad range of bioactivities like cancer therapy, anti-inflammatory agents, and acetylcholinesterase inhibitory. This review touches on the main points of the pharmaceutical applications of red seaweed, as well as the exploitation of their specific compounds and secondary metabolites with vital roles.

Targeting antimicrobial drug resistance with marine natural products

The rise and spread of antimicrobial resistance represents one of the most pressing health issues of today. Antimicrobial resistance in micro-organisms can arise due to a multiplicity of factors, including permeability changes in the cell membrane, increase of drug efflux pumps, enzymatic modification or inactivation of the antibiotic, target site modification, alternative metabolic pathways and biofilm formation. The marine environment is a valuable source of diverse natural products with a huge variety of biological activities. Among them, antimicrobial compounds show promising biological activities against numerous drug-resistant bacteria and fungi, making marine natural products a very promising resource in the search for novel antimicrobial agents. This review summarises the state-of-art of marine natural products with antibacterial and antifungal properties against drug-resistant micro-organisms. These natural products were categorised based on their chemical structure, and their respective sources and activities are highlighted. The chemical diversity associated with these marine-derived molecules is enormous, including peptides, polyketides, alkaloids, sterols, terpenoids, lactones, halogenated compounds, nucleosides, etc., some of which have rare substructures. Some of the marine compounds mentioned do not have intrinsic antimicrobial activity but potentiate the antimicrobial effect of other antimicrobials via inhibition of efflux pumps. Although these agents are still in preclinical studies, evidence of their in vivo efficacy suggest research of new drugs from the ocean to overcome antimicrobial resistance in order to fulfil an unmet medical need.