The progress in the research of antiplatelet agents (1995-2017)

Design and characterization of antithrombotic ClEKnsTy-Au nanoparticles as diagnostic and therapeutic reagents

Thrombosis can cause various cardiovascular diseases, which seriously endanger human life. Development of diagnostic and therapeutic reagents for thrombosis at an early stage would be helpful for the improvement of treatment and the reduction of mortality. In the present study, based on an antithrombotic peptide lEKnsTy (lowercase letters represent D-amino acid residues), a diagnostic and therapeutic reagent targeting collagen and the early stage of thrombosis was proposed, where cysteine was introduced into the amino terminus of lEKnsTy to prepare ClEKnsTy, followed by coupling with AuNPs to prepare nanoconjugate AuNP-Cl. The binding of AuNP-Cl on the collagen surface was then confirmed by the molecular dynamics simulations of the binding of ClEKnsTy on collagen, and the experimental results of the binding of AuNP-Cl on collagen. The inhibition of platelet adhesion on the collagen surface by AuNP-Cl was also confirmed. Moreover, the good imaging ability of AuNP-Cl was confirmed by dark-field microscopy. These results indicated that AuNP-Cl was a potential effective diagnostic and therapeutic reagent targeting collagen, which would be helpful for the research and development of multifunctional antithrombotic reagents.

Therapeutic charisma of imidazo [2,1-b] [1,3,4]-thiadiazole analogues: a patent review

Imidazothiadiazole was discovered around the 1950s era, containing an imidazole ring fused to a thiadiazole ring. Imidazothiadiazole exhibit versatile pharmacological properties including anticonvulsant, cardiotonic, anti-inflammatory, diuretic, antifungal, antibacterial and anticancer. Despite of the being discovered in 1950s, the imidazothiadiazole derivatives are unable to being processed to clinical trials because of lack of bioavailability, efficacy and cytotoxicity. The recent patent literature focused on structural modification of imidazothiadiazole core to overcome these problems. This review limelight a disease-centric perspective on patented imidazothiadiazole from 2015-2023 and to understand their mechanism of action in related diseases. The relevant granted patent applications were located using patent databases, Google Patents, USPTO, EPO, WIPO, Espacenet and Lens.

Mechanisms of thrombosis and research progress on targeted antithrombotic drugs

Globally, the incidence of thromboembolic diseases has increased in recent years, accompanied by an increase in patient mortality. Currently, several targeting delivery strategies have been developed to treat thromboembolic diseases. In this review, we discuss the mechanisms of thrombolysis and current anticoagulant drugs, particularly those with targeting capability, highlighting advances in the accurate treatment of thrombolysis with fewer adverse effects. Such approaches include magnetic drug-loading systems combined with molecular imaging to recanalize blood vessels and systems based on chimeric Arg-Gly-Asp (RGD) sequences that can target platelet glycoprotein receptor. With such progress in targeted antithrombotic drugs, targeted thrombolysis treatment shows significant potential benefit for patients.

The PI3Kδ Inhibitor Idelalisib Diminishes Platelet Function and Shows Antithrombotic Potential

Background: Clinical management of ischemic events and prevention of vascular disease is based on antiplatelet drugs. Given the relevance of phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) as a candidate target in thrombosis, the main goal of the present study was to identify novel antiplatelet agents within the existing inhibitors blocking PI3K isoforms. Methods: We performed a biological evaluation of the pharmacological activity of PI3K inhibitors in platelets. The effect of the inhibitors was evaluated in intracellular calcium release and platelet functional assays, the latter including aggregation, adhesion, and viability assays. The in vivo drug antithrombotic potential was assessed in mice undergoing chemically induced arterial occlusion, and the associated hemorrhagic risk evaluated by measuring the tail bleeding time. Results: We show that PI3K Class IA inhibitors potently block calcium mobilization in human platelets. The PI3K p110δ inhibitor Idelalisib inhibits platelet aggregation mediated by ITAM receptors GPVI and CLEC-2, preferentially by the former. Moreover, Idelalisib also inhibits platelet adhesion and aggregation under shear and adhesion to collagen. Interestingly, an antithrombotic effect was observed in mice treated with Idelalisib, with mild bleeding effects at high doses of the drug. Conclusion: Idelalisib may have antiplatelet effects with minor bleeding effects, which provides a rationale to evaluate its antithrombotic efficacy in humans.

A novel di-peptide Met-Glu from collagen hydrolysates inhibits platelet aggregation and thrombus formation via regulation of Gq-mediated signaling

Increasing evidence has shown that collagen peptides had various biological activities. In this study, a novel antiplatelet peptide Met-Glu (ME) was separated and identified from silver carp skin by YMC ODS-A C18 separation and ESI-MS/MS analysis. Peptide ME inhibited platelet aggregation and secretion of platelet granules induced by ADP, thrombin and collagen, and significantly attenuated ferric chloride-induced thrombus formation in rats. It did not prolong the bleeding time in mice even at the dose of 300 μmol/kg body weight that showed potent anti-thrombosis effects. Additionally, peptide ME targeted at Gq-protein to downregulate the phosphorylation of PLCβ, an important upstream effector of PI3K/Akt and Erk/MAPK signaling to inhibit intracellular calcium ion mobilization. These results suggest that peptide ME inhibited thrombosis in vivo and inhibited Gq-mediated signaling in platelets, indicating the possibility that ME could potentially be developed as a novel therapeutic agent in the prevention and treatment of thrombotic diseases. PRACTICAL APPLICATIONS: Cardiovascular diseases (CVDs) are the leading cause of mortality and morbidity worldwide. The proximal cause of CVDs is intravascular thrombosis formation, which mostly results from platelet activation, aggregation, and granules secretion. Traditional drugs in the prevention of thrombotic disease, such as aspirin and clopidogrel, are still limited for their side effects, especially bleeding complications. Collagen is a natural source for bioactive peptides and our previous study has shown that collagen peptides could inhibit platelet aggregation in vitro. Understanding the mechanism of collagen peptides on regulation of platelet activation and their in vivo anti-thrombosis activities were important for the development of novel-specific medical food in the prevention of thrombotic diseases.

Novel compounds of hybrid structure pyridazinone–coumarin as potent inhibitors of platelet aggregation

Aim: The current limitations of antiplatelet therapy promote the search for new antithrombotic agents. Here we describe novel platelet aggregation inhibitors that combine pyridazinone and coumarin scaffolds in their structure. Results: The target compounds were synthesized in good yield from maleic anhydride, following a multistep strategy. The in vitro studies demonstrated significant antiplatelet activity in many of these compounds, with IC50 values in the low micromolar range, revealing that the activity was affected by the substitution pattern of the two selected cores. Additional studies point out their effect as inhibitors of glycoprotein (Gp) IIb/IIIa activation. Conclusion: This novel hybrid structure can be considered a good prototype for the development of potent platelet aggregation inhibitors.

Progress in the development of antiplatelet agents: Focus on the targeted molecular pathway from bench to clinic

Antiplatelet drugs serve as a first-line antithrombotic therapy for the management of acute ischemic events and the prevention of secondary complications in vascular diseases. Numerous antiplatelet therapies have been developed; however, currently available agents are still associated with inadequate efficacy, risk of bleeding, and variability in individual response. Understanding the mechanisms of platelet involvement in thrombosis and the clinical development process of antiplatelet agents is critical for the discovery of novel agents. The functions of platelets in thrombosis are regulated by two major mechanisms: the interaction between surface receptors and their ligands, and the downstream intracellular signaling pathways. Recently, most of the progress made in antiplatelet drug development has been achieved with P2Y receptor antagonists. Additionally, the usage of GP IIb/IIIa receptor antagonists has decreased, because it is associated with a higher risk of bleeding and thrombocytopenia. Agents targeting other platelet surface receptors such as PARs, TP receptor, EP3 receptor, GPIb-IX-V receptor, P-selectin, as well as intracellular signaling factors, such as PI3Kβ, have been evaluated in an attempt to develop the next generation of antiplatelet drugs, reduce or eliminate interpatient variability of drug efficacy and significantly lower the risk of drug-induced bleeding. The aim of this review is to describe the pathways of platelet activation in thrombosis, and summarize the development process of antiplatelet agents, as well as the preclinical and clinical evaluations performed on these agents.

Developments in inhibiting platelet aggregation based on different design strategies

Platelet aggregation is the central event in hemostasis and thrombosis. Up to now, many agents inhibiting platelet aggregation have been approved for the treatment of thrombotic disorders. In this review, we mainly summarized the progress in the research of platelet aggregation inhibitors based on different design strategies. The advantage and challenge of corresponding targets are also discussed in this article. We hope more platelet aggregation inhibitors with efficacy and safety will be discovered in the future.

Bioactive peptides and proteins as alternative antiplatelet drugs

Antiplatelet drugs reduce the risks associated with atherothrombotic events and show various applications in diverse cardiovascular diseases including myocardial infarctions. Efficacy of the current antiplatelet medicines including aspirin, clopidogrel, prasugrel and ticagrelor, and the glycoprotein IIb/IIIa antagonists, are limited due to their increased risks of bleeding, and antiplatelet drug resistance. Hence, it is important to develop new effective antiplatelet drugs, with fewer side-effects. The vast repertoire of natural peptides can be explored towards this goal. Proteins and peptides derived from snake venoms and plants represent exciting candidates for the development of novel and potent antiplatelet agents. Consequently, this review discusses multiple peptides that have displayed antiplatelet aggregation activity in preclinical drug development stages. This review also describes the antiplatelet mechanisms of the peptides, emphasizing the signaling pathways intervened by them. Also, the hurdles encountered during the development of peptides into antiplatelet drugs have been listed. Finally, hitherto unexplored peptides with the potential to prevent platelet aggregation are explored.

AOS ameliorates monocrotaline-induced pulmonary hypertension by restraining the activation of P-selectin/p38MAPK/NF-κB pathway in rats

Perivascular inflammation, vascular luminal area reduction and hemodynamics changes are important pathophysiologic bases of pulmonary hypertension (PH). In this study, PH was induced by an intraperitoneal single injection of monocrotaline (MCT, 60 mg/kg). Alginate oligosaccharides (AOS), one of the most famous marine drugs, provided protections in the perivascular inflammation, vascular luminal area reduction and hemodynamics changes of the PH rat induced by MCT. The downregulation of P-selectin plays an important role in the protective effects of AOS against MCT induced PH. The results showed that the treatment with AOS (5, 10, or 20 mg/kg) dose-dependently decreased the expression of P-selectin in serum, pulmonary tissue and pulmonary artery of MCT-induced pulmonary arterial hypertension rats. What's more, the study showed that the protective effects were mediated by the inhibition of p38MAPK/NF-κB pathway, which was caused by reducing the p-p38MAPK protein expression, IκBα degradation and nuclear transcription of NF-κB protein in the pulmonary artery of MCT-induced PH rats. These findings provided an alternative potent medicine for the prevention and therapy of PH.

Heptapeptide-based modification leading to enhancing the action of MTCA on activated platelets, P-selectin, GPIIb/IIIa

AIM

The modification of platelet inhibitor to enhance its targeting capacity toward platelets is of clinical importance. Thus, (1R, 3S)-1-methyl-1, 2, 3, 4-tetrahydro-β-carboline-3-carboxylic acid (MTCA), a platelet inhibitor, was modified with Lys(Pro-Ala-Lys)-Arg-Gly-Asp-Val (KKV), platelet targeting peptide, to form MTCA-KKV.

MATERIALS & METHODS

MTCA and MTCA-KKV were synthesized to identify the effect of KKV modification on MTCA and platelets.

RESULTS

Atomic force microscopy imaged MTCA-KKV effectively accumulated on activated platelets. UV spectra showed that MTCA-KKV concentration dependently changed P-selectin and GPIIb/IIIa conformations. For platelet aggregation, the IC₅₀ of MTCA-KKV was approximately 1/10 folds of MTCA.

CONCLUSION

KKV modification led to forming MTCA-KKV that is superior to MTCA in terms of accumulating on activated platelets, targeting P-selectin and GPIIb/IIIa and inhibiting platelet aggregation. MTCA-KKV could be a promising lead for further investigation.