UNASSIGNED: Despite the progress in comprehending molecular design principles and biochemical processes associated with thrombin inhibition, there is a crucial need to optimize efforts and curtail the recurrence of synthesis-testing cycles. Nitrogen and N-heterocycles are key features of many anti-thrombin drugs. Hence, a pragmatic analysis of nitrogen and N-heterocycles in thrombin inhibitors is important throughout the drug discovery pipeline. In the present work, the authors present an analysis with a specific focus on understanding the occurrence and distribution of nitrogen and selected N-heterocycles in the realm of thrombin inhibitors.
UNASSIGNED: A dataset comprising 4359 thrombin inhibitors is used to scrutinize various categories of nitrogen atoms such as ring, non-ring, aromatic, and non-aromatic. In addition, selected aromatic and aliphatic N-heterocycles have been analyzed.
UNASSIGNED: The analysis indicates that ~62% of thrombin inhibitors possess five or fewer nitrogen atoms. Substituted N-heterocycles have a high occurrence, like pyrrolidine (23.24%), pyridine (20.56%), piperidine (16.10%), thiazole (9.61%), imidazole (7.36%), etc. in thrombin inhibitors.
UNASSIGNED: The majority of active thrombin inhibitors contain nitrogen atoms close to 5 and a combination of N-heterocycles like pyrrolidine, pyridine, piperidine, etc. This analysis provides crucial insights to optimize the transformation of lead compounds into potential anti-thrombin inhibitors.

UNASSIGNED: In patients with atrial fibrillation (AF), direct oral anticoagulants (DOACs) have been utilized as an alternative to warfarin, which is known to have several limitations. This study aimed to clarify the selection criteria for anticoagulants, considering both individual patient factors and the differences between various drugs.
UNASSIGNED: This study conducted a web-based questionnaire from September 20, 2023 to October 3, 2023, among physicians who were members of a cardiology-specific website.
UNASSIGNED: In total, 172 respondents were enrolled in this study. Edoxaban was the most frequently selected anticoagulant (39.1%), followed by apixaban (32.7%) and rivaroxaban (16.8%). Logistic regression analysis revealed that increased concern for adherence enhanced the frequency of selecting edoxaban (odds ratio [OR] = 2.42; p = 0.047), with the opposite trend observed for dabigatran (OR = 0.404; p = 0.029). The selection of apixaban is related to whether the patient is able to maintain a regular lifestyle, including adherence to medication schedules (OR = 1.874; p = 0.031). Furthermore, detailing activities from a medical representative, especially regarding a new indication, were found to influence drug selection for rivaroxaban (OR = 2.422; p = 0.047).
UNASSIGNED: This study revealed that edoxaban is the most frequently selected anticoagulant. Although prescribing cardiologists select drugs based on background factors, adherence to medication and information from medical representatives were also crucial factors in the selection process.

In this study, thrombin was immobilized with magnetic particles modified by glutaraldehyde. The changes in secondary structures of immobilized enzyme revealed an increment in conformational rigidity and stability, which can be reflected in temperature and pH stability as well as the tolerance of organic reagents. The optimal reutilization times of magnetic particle immobilized thrombin were 7 times, and the half-life of enzyme activity preserved at room temperature was 5 days, which was 2.5 times higher than that of free enzyme. Ligusticum chuanxiong and Anemarrhenae Rhizoma with high enzyme inhibitory activity were selected for primary screening, and six potential inhibitors of thrombin were identified by HPLC/MS. The results showed that three compounds in Anemarrhenae Rhizoma had better predictive thrombin inhibitory activity. Through the in vitro thrombin activity inhibition experiment, it was also verified that mangiferin and neo-mangiferin had an ideal thrombin activity inhibition effect, which was consistent with the results of molecular docking.

Thromboprophylaxis is indicated in patients at an elevated risk of developing thrombotic disorders, typically using direct oral anticoagulants or low-molecular-weight heparins. We postulated that transient thromboprophylaxis (days-weeks) could be provided by a single dose of an anticoagulant engineered for prolonged pharmacokinetics. In the present work, d-phenylalanyl-l-prolyl-l-arginine chloromethyl ketone (PPACK) was used as a model anticoagulant to test the hypothesis that conjugation of thrombin inhibitors to the surface of albumin would provide durable protection against thrombotic insults. Covalent conjugates were formed between albumin and PPACK using click chemistry, and they were tested in vitro using a thrombin activity assay and a clot formation assay. Thromboprophylactic efficacy was tested in mouse models of arterial thrombosis, both chemically induced (FeCl3) and following ischemia-reperfusion (transient middle cerebral artery occlusion; tMCAO). Albumin-PPACK conjugates were shown to have nanomolar potency in both in vitro assays, and following intravenous injection had prolonged circulation. Conjugates did not impact hemostasis (tail clipping) or systemic coagulation parameters in normal mice. Intravenous injection of conjugates prior to FeCl3-induced thrombosis provided significant protection against occlusion of the middle cerebral and common carotid arteries, and injection immediately following ischemia-reperfusion reduced stroke volume measured 3 days after injury by ∼40% in the tMCAO model. The data presented here provide support for the use of albumin-linked anticoagulants as an injectable, long-circulating, safe thromboprophylactic agent. In particular, albumin-PPACK provides significant protection against thrombosis induced by multiple mechanisms, without adversely affecting hemostasis.

Thrombin, a crucial enzyme involved in blood coagulation and associated diseases, requires accurate detection of its activity and screening of inhibitors for clinical diagnosis and drug discovery. To address this, an electrochemiluminescence (ECL) method was developed to detect thrombin activity based on the sensitization of Ti3C2Tx MXene, which could sensitize the Ru(bpy)32+ ECL system greatly. The thrombin-cleavable substrate bio-S-G-R-P-V-L-G-C was used as recognizer to evaluate the activity of thrombin. Under the optimal conditions, the limit of detection for thrombin in serum was 83 pU/mL (S/N = 3) with a linear range from 0.1 nU/mL to 1 µU/mL. Moreover, the developed ECL biosensor was employed to screen for thrombin inhibitors from Artemisiae argyi Folium. Four potential thrombin inhibitors (isoquercitrin, nepetin, L-camphor, L-borneol) were screened out with inhibition rates beyond 50%, among which isoquercitrin had the best inhibition rate of 90.26%. Isoquercitrin and nepetin were found to be competitive inhibitors of thrombin, with [Formula: see text] values of 0.91 μM and 2.18 μM, respectively. Molecular docking results showed that these compounds could interact with the active sites of thrombin through hydrogen bonds including ASP189, SER195, GLY216, and GLY219. The electrochemical biosensor constructed provides a new idea for the detection of thrombin activity and screening of its inhibitors.

Ecarin is a venom from the saw-scaled viper, Echis carinatus, which catalyzes prothrombin into meizothrombin. This venom is used in several hemostasis laboratory assays, including ecarin clotting time (ECT) and ecarin chromogenic assays (ECA). The use of these ecarin-based assays was first implemented as a tool for monitoring the infusion of a direct thrombin inhibitor, hirudin. Subsequently, this method has been more recently employed for measuring either the pharmacodynamic or pharmacokinetic properties of the oral direct thrombin inhibitor, dabigatran. In this chapter, the procedure for performing manual ECT and automated and manual ECA for measuring thrombin inhibitors is described.

The rational discovery of new peptidomimetic inhibitors of the coagulation factor Xa (fXa) could help set more effective therapeutic options (to prevent atrial fibrillation). In this respect, we explored the conformational impact on the enzyme inhibition potency of the malonamide bridge, compared to the glycinamide one, as a linker connecting the P1 benzamidine anchoring moiety to the P4 aryl group of novel selective fXa inhibitors. We carried out structure-activity relationship (SAR) studies aimed at investigating para- or meta-benzamidine as the P1 basic group as well as diversely decorated aryl moieties as P4 fragments. To this end, twenty-three malonamide derivatives were synthesized and tested as inhibitors of fXa and thrombin (thr); the molecular determinants behind potency and selectivity were also studied by employing molecular docking. The malonamide linker, compared to the glycinamide one, does significantly increase anti-fXa potency and selectivity. The meta-benzamidine (P1) derivatives bearing 2\',4\'-difluoro-biphenyl as the P4 moiety proved to be highly potent reversible fXa-selective inhibitors, achieving inhibition constants (Ki) in the low nanomolar range. The most active compounds were also tested against cholinesterase (ChE) isoforms (acetyl- or butyrylcholinesterase, AChE, and BChE), and some of them returned single-digit micromolar inhibition potency against AChE and/or BChE, both being drug targets for symptomatic treatment of mild-to-moderate Alzheimer\'s disease. Compounds 19h and 22b were selected as selective fXa inhibitors with potential as multimodal neuroprotective agents.

Recent studies concerning products that originate from natural plants have sought to clarify active ingredients, which both explains the mechanisms of the function and aids in quality control during production. As a traditional functional plant, Curcumae Rhizoma (CR) has been proven to be effective in promoting blood circulation and removing blood stasis. However, the components that play a role in its huge compound library are still unclear. The present study aimed to develop a high-throughput screening method to identify thrombin inhibitors in CR and validate them by in vitro and in vivo experiments. The effect of CR on thrombin in HUVECs cells was determined by ELISA, then an affinity-ultrafiltration-UPLC-Q-Exactive Orbitrap/MS approach was applied. Agatroban and adenosine were used as positive and negative drugs respectively to verify the reliability of the established method. The in vitro activity of the compounds was determined by specific substrate S-2238. The in vivo effect of the active ingredients was determined using zebrafish. Molecular docking was used to understand the internal interactions between compounds and enzymes. ELISA results showed that CR had an inhibitory effect on thrombin. The screening method established in this paper is reliable, by which a total of 15 active compounds were successfully identified. This study is the first to report that C7, 8, and 11 have in vitro thrombin-inhibitory activity and significantly inhibit thrombosis in zebrafish models at a safe dose. Molecular docking studies were employed to analyze the possible active binding sites, with the results suggesting that compound 16 is likely a better thrombin inhibitor compared with the other compounds. Based on the affinity-ultrafiltration-UPLC-Q-Exactive Orbitrap/MS approach, a precisely targeted therapy method using bio-active compounds from CR might be successfully established, which also provides a valuable reference for targeted therapy, mechanism exploration, and the quality control of traditional herbal medicine.

In this study; a spectrum-effect relationship analysis combined with a high-performance liquid chromatography-mass spectrometry (LC-MS) analysis was established to screen and identify active components that can inhibit thrombin and factor Xa (THR and FXa) in Salviae Miltiorrhizae Radix et Rhizoma-Chuanxiong Rhizoma (Danshen-Chuanxiong) herbal pair. Ten potential active compounds were predicted through a canonical correlation analysis (CCA), and eight of them were tentatively identified through an LC-MS analysis. Furthermore; the enzyme inhibitory activity of six available compounds; chlorogenic acid; Z-ligustilide; caffeic acid; ferulic acid; tanshinone I and tanshinone IIA; were tested to verify the feasibility of the method. Among them; chlorogenic acid was validated to possess a good THR inhibitory activity with IC50 of 185.08 µM. Tanshinone I and tanshinone IIA are potential FXa inhibitors with IC50 of 112.59 µM and 138.19 µM; respectively. Meanwhile; molecular docking results show that tanshinone I and tanshinone IIA; which both have binding energies of less than -7.0 kcal·mol-1; can interact with FXa by forming H-bonds with residues of SER214; GLY219 and GLN192. In short; the THR and FXa inhibitors in the Danshen-Chuanxiong herbal pair have been successfully characterized through a spectrum-effect relationship analysis and an LC-MS analysis.

BACKGROUND: Severe bleeding under antithrombotic therapy is common and challenging in intensive care medicine; on the one hand, rapid bleeding control must be achieved and, on the other hand, thromboembolic complications must be avoided.
OBJECTIVE: The paper will provide a brief overview of direct oral anticoagulants, therapeutic options and precise instructions for dealing with severe bleeding.
RESULTS: In addition to general measures in direct oral anticoagulant (DOAC)-associated major bleeding, prothrombin complex concentrate (PCC), idarucizumab and andexanet alfa are available as specific antidote therapy. In case of bleeding under heparin therapy, protamine sulfate is available as a possible antidote.
CONCLUSIONS: In particular, the importance of andexanet alfa in the treatment of factor Xa inhibitor-associated bleeding requires further investigation.
UNASSIGNED: HINTERGRUND: Schwere Blutungen unter antithrombotischer Therapie sind im intensivmedizinischen Alltag häufig und herausfordernd, einerseits muss eine rasche Blutungskontrolle erreicht werden, andererseits müssen thromboembolische Komplikationen vermieden werden.
UNASSIGNED: In dem Leitthemenbeitrag wird eine kurze Übersicht über die direkten oralen Antikoagulanzien, therapeutische Optionen und konkrete Handlungsanweisungen gegeben.
UNASSIGNED: Neben Allgemeinmaßnahmen bei mit direkten oralen Antikoagulanzien (DOAK-)assoziierten Majorblutungen stehen im Wesentlichen Prothrombinkonzentrate (PPSB) und Idarucizumab als Antidottherapie zur Verfügung. Bei Blutungen unter Heparinen steht als mögliches Antidot Protaminsulfat zur Verfügung.
UNASSIGNED: Insbesondere zum Stellenwert von Andexanet alfa in der Therapie von Faktor-Xa-Inhibitor-assoziierten Blutungen sind weitere Studien erforderlich.