Search Results (17)

Blood transports nutrients and oxygen to the cells while removing the waste. It also possesses a hemostasis function to prevent excessive bleeding. However, abnormal clot formation (thrombosis) within healthy blood vessels can lead to life-threatening conditions like heart attacks, strokes, and pulmonary embolism. This review explores anticoagulants, their historical aspects, current clinical applications, and future trends. Anticoagulants play a critical role in preventing and treating thrombosis by interfering with different stages of blood clotting. The journey began with heparin, a rapidly acting injectable medication discovered in 1916. The introduction of warfarin in the 1950s revolutionized anticoagulation by offering long-term oral regimens. Today, anticoagulants are crucial for managing conditions like deep vein thrombosis and pulmonary embolism, especially in an aging population with a rising prevalence of thrombotic complications. Three main types of anticoagulants are used today: vitamin K antagonists (VKAs), injectable heparins, and direct oral anticoagulants (DOACs). Despite advancements, managing anticoagulant therapy remains complex due to individual patient variability, the need for regular monitoring, and the delicate balance between preventing thrombosis and bleeding risks. Emerging trends include the development of factor XIa inhibitors, which promise more targeted thrombosis prevention with potentially lower bleeding risks. This review highlights the ongoing innovation in anticoagulant development, the need for precise management, and potential future avenues like factor XIa inhibitors. Additionally, artificial intelligence holds promise for improving patient outcomes and addressing the complexities of thrombotic disease management by personalizing therapy and reducing bleeding risks. Full article

Coagulation factor XIa is a new serine-protease family drug target for next-generation anticoagulants. With the snake venom Kunitz-type peptide BF9 as the scaffold, we obtained a highly active XIa inhibitor BF9-N17K in our previous work, but it also inhibited the hemostatic target plasmin. Here, in order to enhance the selectivity of BF9-N17K toward XIa, four mutants, BF9-N17K-L19A, BF9-N17K-L19S, BF9-N17K-L19D, and BF9-N17K-L19K, were further designed using the P2′ amino acid classification scanning strategy. The anticoagulation assay showed that the four P2′ single-point mutants still had apparent inhibitory anticoagulation activity that selectively inhibited the human intrinsic coagulation pathway and had no influence on the extrinsic coagulation pathway or common coagulation pathway, which indicated that the single-point mutants had minimal effects on the anticoagulation activity of BF9-N17K. Interestingly, the enzyme inhibitor assay experiments showed that the XIa and plasmin inhibitory activities were significantly changed by the P2′ amino acid replacements. The XIa inhibitory activity of BF9-N17K-L19D was apparently enhanced, with an IC₅₀ of 19.28 ± 2.53 nM, and its plasmin inhibitory was significantly weakened, with an IC₅₀ of 459.33 ± 337.40 nM. BF9-N17K-L19K was the opposite to BF9-N17K-L19D, which had enhanced plasmin inhibitory activity and reduced XIa inhibitory activity. For BF9-N17K-L19A and BF9-N17K-L19S, no apparent changes were found in the serine protease inhibitory activity, and they had similar XIa and plasmin inhibitory activities to the template peptide BF9-N17K. These results suggested that the characteristics of the charge of the P2′ site might be associated with the drug selectivity between the anticoagulant target XIa and hemostatic target plasmin. In addition, according to the molecular diversity and sequence conservation, a common motif GR/PCR/KA/SXIP-XYGGC is proposed in the XIa-inhibitory Kunitz-type peptides, which might provide a new clue for further peptide engineering. In conclusion, through P2′ amino acid classification scanning with the snake venom Kunitz-type peptide scaffold, a new potent and selective XIa inhibitor, BF9-N17K-L19D, was discovered, which provides a new XIa-targeting lead drug template for the treatment of thrombotic-related diseases. Full article

Recent studies have revealed that the coagulation system plays a role in mammalian innate defense by entrapping bacteria in clots and generating antibacterial peptides. So, it is very important for the survival of bacteria to defend against the host coagulation system, which suggests that bacterial exotoxins might be a new source of anticoagulants. In this study, we analyzed the genomic sequences of Acinetobacter baumannii and a new bacterial exotoxin protein, F6W77, with five Kunitz-domains, KABP1-5, was identified. Each Kunitz-type domain features a classical six-cysteine framework reticulated by three conserved disulfide bridges, which was obviously similar to animal Kunitz-domain peptides but different from plant Kunitz-domain peptides. Anticoagulation function evaluation showed that towards the intrinsic coagulation pathway, KABP1 and KABP5 had apparently inhibitory activity, KABP4 had weak inhibitory activity, and KBAP2 and KABP3 had no effect even at a high concentration of 20 μg/mL. All five Kunitz-domain peptides, KABP1-5, had no inhibitory activity towards the extrinsic coagulation pathway. Enzyme-inhibitor experiments showed that the high-activity anticoagulant peptide KABP1 had apparently inhibitory activity towards two key coagulation factors, Xa and XIa, which was further confirmed by pull-down experiments that showed that KABP1 can bind to coagulation factors Xa and XIa directly. Structure-function relationship analyses of five Kunitz-type domain peptides showed that the arginine of the P1 site of three new bacterial anticoagulants, KABP1, KABP4 and KABP5, might be the key residue for their anticoagulation activity. In conclusion, with bioinformatics analyses, peptide recombination, and functional evaluation, we firstly found bacterial-exotoxin-derived Kunitz-type serine protease inhibitors with selectively inhibiting activity towards intrinsic coagulation pathways, and highlighted a new interaction between pathogenic bacteria and the human coagulation system. Full article

Direct oral anticoagulants (DOACs) are increasingly used for the treatment of thrombosis. While inhibitors of factor IIa and factor Xa have shown effectiveness, the risk of bleeding remains a significant concern. Recently, direct factor XIa inhibitors—including asundexian and milvexian—have emerged as potential anticoagulation therapies, based on clinical observations that patients with factor XIa deficiencies seldom present with spontaneous bleeding tendencies. The interferences associated with DOACs in routine and specialised coagulation assays are well-described; however, the interferences associated with emerging FXIa inhibitors are largely uncharacterised. Here, we briefly report the impact of asundexian and milvexian in routine coagulation assays using in vitro plasma-based systems. Asundexian and milvexian induce concentration-dependent prolongations in APTT-based assays with curvilinear regressions, which may be suitable for the measurement of pharmacodynamic effects at peak levels ex vivo. We also report differential sensitivities of APTT-based assays—particularly at higher FXIa inhibitor concentrations—highlighting the clinical need for an extensive evaluation of interferences associated with FXIa inhibitors in coagulation assays. Full article

Pulmonary embolism (PE) is a potentially life-threatening condition requiring prompt diagnosis and treatment. Recent advances have led to the development of newer techniques and drugs aimed at improving PE management, reducing its associated morbidity and mortality and the complications related to anticoagulation. This review provides an overview of the current knowledge and future perspectives on PE treatment. Anticoagulation represents the first-line treatment of hemodynamically stable PE, direct oral anticoagulants being a safe and effective alternative to traditional anticoagulation: these drugs have a rapid onset of action, predictable pharmacokinetics, and low bleeding risk. Systemic fibrinolysis is suggested in patients with cardiac arrest, refractory hypotension, or shock due to PE. With this narrative review, we aim to assess the state of the art of newer techniques and drugs that could radically improve PE management in the near future: (i) mechanical thrombectomy and pulmonary embolectomy are promising techniques reserved to patients with massive PE and contraindications or failure to systemic thrombolysis; (ii) catheter-directed thrombolysis is a minimally invasive approach that can be suggested for the treatment of massive or submassive PE, but the lack of large, randomized controlled trials represents a limitation to widespread use; (iii) novel pharmacological approaches, by agents inhibiting thrombin-activatable fibrinolysis inhibitor, factor Xia, and the complement cascade, are currently under investigation to improve PE-related outcomes in specific settings. Full article

Cardiovascular diseases caused by blood coagulation system disorders are one of the leading causes of morbidity and mortality in the world. Research shows that blood clotting factors are involved in these thrombotic processes. Among them, factor Xa occupies a key position in the blood coagulation cascade. Another coagulation factor, XIa, is also a promising target because its inhibition can suppress thrombosis with a limited contribution to normal hemostasis. In this regard, the development of dual inhibitors as new generation anticoagulants is an urgent problem. Here we report the synthesis and evaluation of novel potential dual inhibitors of coagulation factors Xa and XIa. Based on the principles of molecular design, we selected a series of compounds that combine in their structure fragments of pyrrolo[3,2,1-ij]quinolin-2-one and thiazole, connected through a hydrazine linker. The production of new hybrid molecules was carried out using a two-stage method. The reaction of 5,6-dihydropyrrolo[3,2,1-ij]quinoline-1,2-diones with thiosemicarbazide gave the corresponding hydrazinocarbothioamides. The reaction of the latter with DMAD led to the target methyl 2-(4-oxo-2-(2-(2-oxo-5,6-dihydro-4H-pyrrolo[3,2,1-ij]quinolin-1(2H)-ylidene)hydrazineyl)thiazol-5(4H)-ylidene)acetates in high yields. In vitro testing of the synthesized molecules revealed that ten of them showed high inhibition values for both the coagulation factors Xa and XIa, and the IC₅₀ value for some compounds was also assessed. The resulting structures were also tested for their ability to inhibit thrombin. Full article

Introduction: Despite preventive measures, stroke rates remain high in the primary and secondary prevention settings. Factor XIa inhibition may offer a novel, safe and effective antithrombotic option for stroke prevention. Methods: We conducted a systematic review and meta-analysis including all available randomized controlled clinical trials (RCTs) that investigated the efficacy and safety of factor XIa inhibitors versus controls in primary or secondary stroke prevention. The primary efficacy and safety outcomes of interest were symptomatic ischemic stroke (IS) and the composite of major bleeding and clinically relevant non-major bleeding. Results: Four phase II dose-finding RCTs were included, comprising a total of 4732 patients treated with factor XIa inhibitors versus 1798 controls. Treatment with factor XIa inhibitors did not reduce the risk of IS compared to controls (RR: 0.89; 95% CI: 0.67–1.17). The composite of symptomatic IS and covert infarcts on brain MRI (RR: 1.01; 95% CI: 0.87–1.18), the composite of symptomatic IS and transient ischemic attack (TIA; RR: 0.78; 95% CI: 0.61–1.01), and the composite of major adverse cardiovascular events (RR: 1.07; 95% CI: 0.87–1.31) did not differ between the treatment groups. Treatment with factor XIa inhibitors did not increase the risk of the composite of major bleeding and clinically relevant non-major bleeding (RR: 1.19; 95% CI: 0.65–2.16), major bleeding alone (RR: 1.19; 95% CI: 0.64–2.22), intracranial bleeding (RR: 0.91; 95% CI: 0.26–3.19) or all-cause mortality (RR: 1.21; 95% CI: 0.77–1.90). Conclusion: This meta-analysis provides reassuring evidence regarding the safety of factor XIa inhibitors. These findings, coupled with potential signals of efficacy in reducing IS (and TIA), underscore the importance of ongoing phase III RCTs for providing definitive data regarding the effect of factor XIa inhibition on stroke prevention. Full article

Venous thromboembolism (VTE), comprising pulmonary embolism (PE) and deep vein thrombosis (DVT), poses a significant risk during and after hospitalization, particularly for surgical patients. Among various patient groups, those undergoing major orthopedic surgeries are considered to have a higher susceptibility to PE and DVT. Major lower-extremity orthopedic procedures carry a higher risk of symptomatic VTE compared to most other surgeries, with an estimated incidence of ~4%. The greatest risk period occurs within the first 7–14 days following surgery. Major bleeding is also more prevalent in these surgeries compared to others, with rates estimated between 2% and 4%. For patients undergoing major lower-extremity orthopedic surgery who have a low bleeding risk, it is recommended to use pharmacological thromboprophylaxis with or without mechanical devices. The choice of the initial agent depends on the specific surgery and patient comorbidities. First-line options include low-molecular-weight heparins (LMWHs), direct oral anticoagulants, and aspirin. Second-line options consist of unfractionated heparin (UFH), fondaparinux, and warfarin. For most patients undergoing knee or hip arthroplasty, the initial agents recommended for the early perioperative period are LMWHs (enoxaparin or dalteparin) or direct oral anticoagulants (rivaroxaban or apixaban). In the case of hip fracture surgery, LMWH is recommended as the preferred agent for the entire duration of prophylaxis. However, emerging factor XI(a) inhibitors, as revealed by a recent meta-analysis, have shown a substantial decrease in the occurrence of VTE and bleeding events among patients undergoing major orthopedic surgery. This discovery poses a challenge to the existing paradigm of anticoagulant therapy in this specific patient population and indicates that factor XI(a) inhibitors hold great promise as a potential strategy to be taken into serious consideration. Full article

Background: While current clinically administered anticoagulant medications have demonstrated effectiveness, they have also precipitated significant risks: severe bleeding complications including, but not limited to, gastrointestinal hemorrhaging and intracranial and other life-threatening major bleedings. An ongoing effort is being made to identify the best targets for anticoagulant-targeted drugs. Coagulation factor XIa (FXIa) is emerging as an important target of current anticoagulant treatment. Objective: This review will summarize the development of anticoagulants and recent advances in clinical trials of experimental factor XI inhibitors from a clinical application perspective. Results: As of 1 January 2023, our search screening included 33 clinical trials. We summarized the research progress of FXIa inhibitors from seven clinical trials that evaluated their efficacy and safety. The results showed no statistically meaningful distinction in the primary efficacy between patients receiving FXIa inhibitors compared to controls (RR = 0.796; 95% CI: 0.606–1.046; I² = 68%). The outcomes did not indicate a statistical difference in the occurrence of any bleeding between patients receiving FXIa inhibitors compared to controls (RR = 0.717; 95% CI: 0.502–1.023; I² = 60%). A subgroup analysis found significant differences in severe bleeding and clinically relevant hemorrhaging in subjects receiving FXIa inhibitors compared to Enoxaparin (RR = 0.457; 95% CI: 0.256–0.816; I² = 0%). Conclusions: Clinical trials to date have indicated that factor XIa is a potential anticoagulation target, and factor XIa inhibitors may play an important role in the development of anticoagulants. Full article

Despite extensive research in the field of thrombotic diseases, the prevention of blood clots remains an important area of study. Therefore, the development of new anticoagulant drugs with better therapeutic profiles and fewer side effects to combat thrombus formation is still needed. Herein, we report the synthesis and evaluation of novel pyrroloquinolinedione-based rhodanine derivatives, which were chosen from 24 developed derivatives by docking as potential molecules to inhibit the clotting factors Xa and XIa. For the synthesis of new hybrid derivatives of pyrrolo[3,2,1-ij]quinoline-2-one, we used a convenient structural modification of the tetrahydroquinoline fragment by varying the substituents in positions 2, 4, and 6. In addition, the design of target molecules was achieved by alkylating the amino group of the rhodanine fragment with propargyl bromide or by replacing the rhodanine fragment with 2-thioxoimidazolidin-4-one. The in vitro testing showed that eight derivatives are capable of inhibiting both coagulation factors, two compounds are selective inhibitors of factor Xa, and two compounds are selective inhibitors of factor XIa. Overall, these data indicate the potential anticoagulant activity of these molecules through the inhibition of the coagulation factors Xa and XIa. Full article

Several plant protein inhibitors with anticoagulant properties have been studied and characterized, including the Delonix regia trypsin inhibitor (DrTI). This protein inhibits serine proteases (trypsin) and enzymes directly involved in coagulation, such as plasma kallikrein, factor XIIa, and factor XIa. In this study, we evaluated the effects of two new synthetic peptides derived from the primary sequence of DrTI in coagulation and thrombosis models to understand the mechanisms involved in the pathophysiology of thrombus formation as well as in the development of new antithrombotic therapies. Both peptides acted on in vitro hemostasis-related parameters, showing promising results, prolonging the Partially Activated Thromboplastin Time (aPTT) and inhibited platelet aggregation induced by adenosine diphosphate (ADP) and arachidonic acid. In murine models, for arterial thrombosis induced by photochemical injury, and platelet-endothelial interactions monitored by intravital microscopy, both peptides at doses of 0.5 mg/kg significantly extended the time of artery occlusion and modified the platelet adhesion and aggregation pattern with no changes in bleeding time, demonstrating the high biotechnological potential of both molecules. Full article

Within Neotropical pit-vipers, the Mexican/Central-American clade consisting of Atropoides, Cerrophidion, Metlapilcoatlus, and Porthidium is a wide-ranging, morphologically and ecologically diverse group of snakes. Despite their prevalence, little is known of the functional aspects of their venoms. This study aimed to fill the knowledge gap regarding coagulotoxic effects and to examine the potential of different therapeutic approaches. As a general trait, the venoms were shown to be anticoagulant but were underpinned by diverse biochemical actions. Pseudo-procoagulant activity (i.e., thrombin-like), characterized by the direct cleavage of fibrinogen to form weak fibrin clots, was evident for Atropoides picadoi, Cerrophidiontzotzilorum, Metlapilcoatlus mexicanus, M. nummifer, M. occiduus, M. olmec, and Porthidium porrasi. In contrast, other venoms cleaved fibrinogen in a destructive (non-clotting) manner, with C. godmani and C. wilsoni being the most potent. In addition to actions on fibrinogen, clotting enzymes were also inhibited. FXa was only weakly inhibited by most species, but Cerrophidion godmani and C. wilsoni were extremely strong in their inhibitory action. Other clotting enzymes were more widely inhibited by diverse species spanning the full taxonomical range, but in each case, there were species that had these traits notably amplified relatively to the others. C. godmani and C. wilsoni were the most potent amongst those that inhibited the formation of the prothrombinase complex and were also amongst the most potent inhibitors of Factor XIa. While most species displayed only low levels of thrombin inhibition, Porthidium dunni potently inhibited this clotting factor. The regional polyvalent antivenom produced by Instituto Picado Clodomiro was tested and was shown to be effective against the diverse anticoagulant pathophysiological effects. In contrast to the anticoagulant activities of the other species, Porthidium volcanicum was uniquely procoagulant through the activation of Factor VII and Factor XII. This viperid species is the first snake outside of the Oxyuranus/Pseudonaja elapid snake clade to be shown to activate FVII and the first snake venom of any kind to activate FXII. Interestingly, while small-molecule metalloprotease inhibitors prinomastat and marimastat demonstrated the ability to prevent the procoagulant toxicity of P. volcanicum, neither ICP antivenom nor inhibitor DMPS showed this effect. The extreme variation among the snakes here studied underscores how venom is a dynamic trait and how this can shape clinical outcomes and influence evolving treatment strategies. Full article

Activated factor XI (FXIa) is an important antithrombotic drug target. Clinical and pre-clinical data have demonstrated that its inhibition attenuates thrombosis with minimal risk of excessive bleeding. We isolated Fasxiator from the venom of banded krait Bungarus fasciatus and subsequently engineered Fasxiator_N17R,L19E, with improved affinity (K_i = 0.9 nM) and selectivity towards FXIa. Here, we assess the in vivo efficacy and bleeding risk of rFasxiator_{N17R, L19E} in pre-clinical animal models. Rats injected intravenously (i.v.) with bolus rFasxiator_{N17R, L19E} showed the specific in vivo attenuation of the intrinsic coagulation pathway, lasting for at least 60 min. We performed the in vivo dose-ranging experiments for rFasxiator_{N17R, L19E} as follows: FeCl₃-induced carotid artery occlusion in rats (arterial thrombosis); inferior vena cava ligation in mice (venous thrombosis); tail bleeding time in both rats and mice (bleeding risk). Head-to-head comparisons were made using therapeutic dosages of unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) for arterial and venous thrombosis, respectively. In the arterial thrombosis model, 2 mg/kg i.v. rFasxiator_N17R,L19E achieved a similar antithrombotic efficacy to that of UFH, with >3-fold lower bleeding time. In the venous thrombosis model, the 10 mg/kg subcutaneous (s.c.) injection of rFasxiator_N17R,L19E achieved similar efficacy and bleeding levels to those of LMWH enoxaparin. Overall, rFasxiator_N17R,L19E represents a promising molecule for the development of FXIa-targeting anticoagulants. Full article

In the modern world, complications caused by disorders in the blood coagulation system are found in almost all areas of medicine. Thus, the development of new, more advanced drugs that can prevent pathological conditions without disrupting normal hemostasis is an urgent task. The blood coagulation factor XIIa is one of the most promising therapeutic targets for the development of anticoagulants based on its inhibitors. The initial stage of drug development is directly related to computational methods of searching for a lead compound. In this study, docking followed by quantum chemical calculations was used to search for noncovalent low-molecular-weight factor XIIa inhibitors in a focused library of druglike compounds. As a result of the study, four low-molecular-weight compounds were experimentally confirmed as factor XIIa inhibitors. Selectivity testing revealed that two of the identified factor XIIa inhibitors were selective over the coagulation factors Xa and XIa. Full article

The anticoagulant activity of lignosulfonic acid sodium (LSAS), a non-saccharide heparin mimetic, was investigated in this study. LSAS is a relatively safe industrial byproduct with similar polyanionic characteristics to that of heparin. Human plasma clotting assays, fibrin polymerization testing, and enzyme inhibition assays were exploited to investigate the anticoagulant activity of LSAS. In normal human plasma, LSAS selectively doubled the activated partial thromboplastin time (APTT) at ~308 µg/mL. Equally, LSAS doubled APTT at ~275 µg/mL in antithrombin-deficient plasma. Yet, LSAS doubled APTT at a higher concentration of 429 µg/mL using factor XI-deficient plasma. LSAS did not affect FXIIIa-mediated fibrin polymerization at 1000 µg/mL. Enzyme assays revealed that LSAS inhibits factor XIa (FXIa) with an IC₅₀ value of ~8 μg/mL. LSAS did not inhibit thrombin, factor IXa, factor Xa, factor XIIIa, chymotrypsin, or trypsin at the highest concentrations tested and demonstrated significant selectivity against factor XIIa and plasmin. In Michaelis–Menten kinetics, LSAS decreased the V_MAX of FXIa hydrolysis of a tripeptide chromogenic substrate without significantly changing its K_M indicating an allosteric inhibition mechanism. The inhibitor also disrupted the generation of FXIa–antithrombin complex, inhibited factor XIIa-mediated and thrombin-mediated activation of the zymogen factor XI to FXIa, and competed with heparin for binding to FXIa. Its action appears to be reversed by protamine sulfate. Structure–activity relationship studies demonstrated the advantageous selectivity and allosteric behavior of LSAS over the acetylated and desulfonated derivatives of LSAS. LSAS is a sulfonated heparin mimetic that demonstrates significant anticoagulant activity in human plasma. Overall, it appears that LSAS is a potent, selective, and allosteric inhibitor of FXIa with significant anticoagulant activity in human plasma. Altogether, this study introduces LSAS as a promising lead for further development as an anticoagulant. Full article