Functional and binding studies of gallic acid showing platelet aggregation inhibitory effect as a thrombin inhibitor / 中草药·英文版

Objective: This study was devoted to identifying natural thrombin inhibitors from traditional Chinese medicine (TCM) and evaluating its biological activity in vitro and binding characteristics. Methods: A combination strategy containing molecular docking, thrombin inhibition assay, surface plasmon resonance (SPR) and molecular dynamics simulation were applied to verify the study result. Results: Gallic acid was confirmed as a direct thrombin inhibitor with IC

A Peptide Microarray-Based Fluorescent and Resonance Light Scattering Assay for Screening Thrombin Inhibitor / 分析化学

A peptide microarray-based fluorescence and resonance light scattering ( RLS ) two readout assay was developed for screening thrombin inhibitors in blood samples. In this assay, the biotinylated peptide microarray was used as the platform. The peptide C-terminal fragments carried biotin sites departed from the slide when the biotinylated peptides were digested by thrombin hydrolysis reaction. The hydrolysis progress was labeled by fluorescence and 30 nm peptide-stabilized gold nanoparticles through the biotin-avidin reaction. In the presence of thrombin inhibitors, the hydrolysis reactions were blocked, and the inhibition capability of inhibitors could be detected by the fluorescent and RLS signal changes. The order of the half maximal inhibitory concentration ( IC50 ) of thrombin inhibitors in pure thrombin solution and spiked human serum were argatrobanHAT-Ⅲ>trypsin inhibitor>E-64>AEBSF. The reversible or irreversible characters of argatroban and HAT-Ⅲ had been estimated in human plasma. Compared with the experimental data of fluorescent and RLS assay in blood sample, the RLS assay labeled by 30 nm gold nanoparticles are more suitable for the inhibitor detection in complicated blood sample.

Analysis of Novel Anticoagulants for Atrial Fibrillation – Pharmacokinetics and Pharmacological Considerations.

Atrial Fibrillation (AF) is the most common arrhythmia. AF is a major risk factor for stoke. Warfarin has been available for more than 60 years and until recently it was the only oral anticoagulant used for the prevention of stroke. Despite the extensive studies and proven efficacy, its utility is limited by multiple factors. Warfarin interacts with a multitude of drugs and foods, has a delayed onset of action, has a narrow therapeutic range, requires routine lab monitoring and exhibits variable responses in patients. The novel agents dabigatran, rivaroxaban and apixaban have the potential to have some of the limitations of warfarin. This article will discuss the pharmacokinetic and pharmacological considerations and different characteristics of the novel anticoagulants when used for the prevention of AF.

Expanding horizons of anticoagulant therapy: Dabigatran etexilate a novel oral anticoagulant.

Thrombo-embolic disease is a major challenging clinical problem associated with significant mortality and morbidity. Anticoagulation with the existing heparin products and vitamin K antagonist (VKA) anticoagulants are still the mainstay of management. However, due to the risk of bleeding and well-documented drawbacks, the quest for a novel oral anticoagulant has led to the clinical development of dabigatran etexilate. Dabigatran etexilate is a direct thrombin (IIa) inhibitor which has recently been approved in India for prevention of venous thromboembolic events (VTE) in patients who have undergone major orthopaedic (total knee or hip replacement) surgery and for prevention of stroke, systemic embolism and reduction of vascular mortality in adult patients with atrial fibrillation. Thus dabigatran etexilate is a promising alternative to the current heparin products and VKAs in patients who require long-term oral anticoagulation.

Expression and Characterization of Thrombin Inhibitor TTI / 中国生物工程杂志

TTI gene coding for Tsetse thrombin inhibitor was modified with E.coli bias codon and expressed in Escherichia coli with high efficiency.Recombinant protein was purified to more than 98% purity.Assay for enzyme activity determination was set up.The result showed that the fusion protein exhibited inhibiting activity for thrombin.Inhibitory rate of purified TTI was 73% when concentration of thrombin and substrate was 10U/ml and 250?mol/L respectively.Inhibition pattern was determined as competitive with Ki at 35?mol/L.

Argatroban Treatment in Acute Ischemic Stroke: Multicenter, Randomized, Aspirin-Controlled Study

BACKGROUND: Argatroban, a direct thrombin inhibitor, has been suggested to be beneficial in acute ischemic stroke by preventing microthrombi formation. The aim of this multicenter, aspirin-controlled, randomized trial is to determine the safety and the efficacy of argatroban compared with aspirin in acute ischemic stroke. METHODS: The patients within 48 hours of noncardioembolic ischemic stroke were recruited from 8 centers. Argatroban was infused continuously at 2.5 mg/hr for the first 48 h, and then 10mg of argatroban was infused over 3 h twice a day on days 3-7. Control group received aspirin 300 mg/day for 7 days. The primary outcome was the NIHSS at 30 days and the secondary outcome was Barthel index (BI) and modified Rankin scale (mRS) at 90 days. The safety was evaluated by the incidence of bleeding complication. RESULTS: A total of 236 patients (123 for argatroban and 113 for aspirin) were included. NIHSS at 30 days, BI at 90 days and mRS at 90 days did not show significant difference between the argatroban and the aspirin group (3.1 +/- 3.1 vs 3.5 +/- 3.0, 88.9 +/- 22.5 vs 86.2 +/- 23.8, 1.4 +/- 1.1 vs 1.6 +/- 1.3, p>0.3, respectively). Post hoc analysis revealed that as for the patients who were treated within 24 hours after onset, numbers of patients with NIHSS=1 at 30 days were larger in the argatroban group (23 of 49) than in the aspirin group (10 of 40) (p=0.03). Bleeding complication was not different between the two groups (2 of 123 vs 0 of 113: p>0.4). CONCLUSIONS: Argatroban treatment is relatively safe in acute ischemic stroke. The efficacy of argatroban is not superior to aspirin. However, argatroban may be more beneficial in some subgroup of stroke patients than aspirin.

LB30057, A Direct Thrombin Inhibitor, Inhibits Vascular Smooth Muscle Cell proliferation in vitro and the Neointimal Hyperplasia in Rat Carotid Injury Model

BACKGROUND: Recent data showed prolonged administration of direct thrombin inhibitor might be needed to counteract the persistent thrombin activity and reduce the neointimal hyperplasia after arterial injury. We hypothesized that prolonged administration of LB30057, orally active direct thrombin inhibitor, might inhibit the vascular smooth muscle cell (SMC) proliferation in vitro and neointimal hyperplasia in rat carotid injury model. METHODS: In phase I, thrombin stimulated [methyl-3H] thymidine uptake was measured after LB30057 administration in cell culture study using rat aortic SMC. In phase II, LB30057 (low-dose: 5mg/kg, bid: mid-dose: 25mg/kg, bid: high-dose: 50mg/kg, bid) or placebo was administrated orally twice a day starting from 30minutes before injury until sacrifice for 14days in separated 2 sets of experiment. The histo-morphometric analysis for lumen area, intimal area, medial area, intima-to-medial ratio was performed. RESULTS: In vitro rat aortic SMC culture study, LB30057 inhibited thrombin-induced thymidine uptake. The mean neointimal area was significantly less in high-dose and mid-dose group than placebo group (high-dose vs. placebo: 0.14+/-0.02mm2 vs. 0.25+/-0.02mm2: mid-dose vs. placebo: 0.16+/-0.02mm2 vs. 0.29+/-0.03mm2, p<0.005) respectively and the mean ratio of neointima to medial area were significantly less in high-dose and mid-dose group than in placebo group (high-dose vs. placebo: 1.20+/-0.57 vs. 1.94+/-0.67, mid-dose vs. placebo: 1.58+/-0.29 vs. 2.39+/-0.27, p<0.05). There was no significant difference in the mean area of internal elastic lamina, external elastic lamina and mean luminal area between groups. In 2nd set experiment, the mean neointimal area (placebo: 0.29+/-0.03mm2, mid-dose: 0.16+/-0.02mm2: p<0.005), the mean area of internal elastic lamina and external elastic lamina were significantly less in mid-dose group than in placebo group. The mean ratio of neointima to medial area was significantly less in mid-dose group(1.58+/-0.29) than in placebo group (2.39+/-0.27) (p<0.05). CONCLUSION: LB30057 inhibits SMC proliferation in a dose dependent manner. Prolonged 14-day oral administration of LB30057 is effective in reducing the neointimal hyperplasia in rat carotid balloon injury model.