Switching a Xanthine Oxidase Inhibitor to a Dual-Target Antagonist of P2Y1 and P2Y12 as an Oral Antiplatelet Agent with a Wider Therapeutic Window in Rats than Ticagrelor

Selective Inhibition of P2Y1 and P2Y12 Receptor Signal Pathways in Platelet Aggregation in Transgenic Cell Lines and Rats by Potassium 2-(1-Hydroxypentyl)-Benzoate, Puerarin and Salvianolic Acid B

AIM

Potassium 2-(1-hydroxypentyl)-benzoate (dl-PHPB), puerarin and salvianolic acid B are three natural products or derivatives that can inhibit platelet aggregation. However, the mechanisms of dl-PHPB, puerarin and salvianolic acid B to inhibit platelet aggregation are still not clear.

METHOD

Here, 2-methylthioadenosine diphosphate (2-MeSADP) was used as an inducer to confirm the effects of three drugs on platelet aggregation and illustrate the corresponding mechanisms.

RESULT

The results indicated that dl-PHPB, puerarin and salvianolic acid B significantly inhibited platelet aggregation both in vivo and in vitro. In addition, the content of IP3, cAMP and intracellular [Ca2+]i were measured in HEK293 cell lines overexpressing P2Y1 and P2Y12. Dl-PHPB and puerarin could obviously reduce 2-MeSADP-induced IP3 increase, but salvianolic acid B showed no effects. Unlike dl-PHPB and puerarin, which had no effects on 2-MeSADP-induced cAMP decrease, salvianolic acid B significantly reversed the reduction of cAMP. Both dl-PHPB and puerarin could decrease the enhanced intracellular [Ca2+]i induced by 2-MeSADP; however, salvianolic acid B showed no effect on intracellular [Ca2+]i elevation.

CONCLUSION

These results suggested that dl-PHPB and puerarin inhibited platelet aggregation via targeting at P2Y1 receptor and P2Y1-Gq-IP3-Ca2+ signal pathway. Differently, salvianolic acid B inhibited platelet aggregation via targeting at P2Y12 receptor and via Gi-AC-cAMP signal pathway.

2-Aryl-1-hydroxyimidazoles possessing antiviral activity against a wide range of orthopoxviruses, including the variola virus

Scientific interest in orthopoxvirus infections and search for new highly effective compounds possessing antiviral activity against orthopoxviruses have significantly increased as a result of worldwide mpox outbreak in 2022. The present work deals with the synthesis of new 2-arylimidazoles exhibiting in vitro activity not only against the vaccinia virus, cowpox virus and ectromelia (mousepox) virus but also against the variola virus. Among the imidazole derivatives under consideration (1-hydroxyimidazoles, 1-methoxyimidazoles, 1-benzyloxyimidazoles, and imidazole N-oxides), the most promising antiviral activity is demonstrated by 1-hydroxyimidazoles, which may exist as two prototropic tautomers. Both of these tautomers may be manifested in different crystal structures of these compounds, according to single-crystal X-ray diffraction analysis, while predominantly one of them (N-hydroxy-tautomeric form) is present in DMSO-d 6 solutions and in the gaseous state, as shown by NMR spectroscopy and quantum-chemical calculations. The leader compound 1-hydroxy-2-(4-nitrophenyl)imidazole 4a demonstrated the highest selectivity indices against the vaccinia virus (SI = 1072) and the variola virus (SI = 373).

Comprehensive insights into potential roles of purinergic P2 receptors on diseases: Signaling pathways involved and potential therapeutics

BACKGROUND

Purinergic P2 receptors, which can be divided into ionotropic P2X receptors and metabotropic P2Y receptors, mediate cellular signal transduction of purine or pyrimidine nucleoside triphosphates and diphosphate. Based on the wide expression of purinergic P2 receptors in tissues and organs, their significance in homeostatic maintenance, metabolism, nociceptive transmission, and other physiological processes is becoming increasingly evident, suggesting that targeting purinergic P2 receptors to regulate biological functions and signal transmission holds significant promise for disease treatment.

AIM OF REVIEW

This review highlights the detailed mechanisms by which purinergic P2 receptors engage in physiological and pathological progress, as well as providing prospective strategies for discovering clinical drug candidates.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The purinergic P2 receptors regulate complex signaling and molecular mechanisms in nervous system, digestive system, immune system and as a result, controlling physical health states and disease progression. There has been a significant rise in research and development focused on purinergic P2 receptors, contributing to an increased number of drug candidates in clinical trials. A few influential pioneers have laid the foundation for advancements in the evaluation, development, and of novel purinergic P2 receptors modulators, including agonists, antagonists, pharmaceutical compositions and combination strategies, despite the different scaffolds of these drug candidates. These advancements hold great potential for improving therapeutic outcomes by specifically targeting purinergic P2 receptors.

Strategies for targeting the P2Y12 receptor in the central nervous system

The purinergic 2Y type 12 receptor (P2Y₁₂R) is a well-known biological target for anti-thrombotic drugs due to its role in platelet aggregation and blood clotting. While the importance of the P2Y₁₂R in the periphery has been known for decades, much less is known about its expression and roles in the central nervous system (CNS), where it is expressed exclusively on microglia - the first responders to brain insults and neurodegeneration. Several seminal studies have shown that P2Y₁₂ is a robust, translatable biomarker for anti-inflammatory and neuroprotective microglial phenotypes in models of degenerative diseases such as multiple sclerosis and Alzheimer's disease. An enduring problem for studying this receptor in vivo, however, is the lack of selective, high-affinity small molecule ligands that can bypass the blood-brain barrier and accumulate in the CNS. In this Digest, we discuss previous attempts by researchers to target the P2Y₁₂R in the CNS and opine on strategies that may be employed to design and assess the suitability of novel P2Y₁₂ ligands for this purpose going forward.

P2Y12 antagonists: Approved drugs, potential naturally isolated and synthesised compounds, and related in-silico studies

P2Y₁₂ is a platelet surface protein which is responsible for the amplification of P2Y₁ response. It plays a crucial role in platelet aggregation and thrombus formation through an ADP-induced platelet activation mechanism. Despite that P2Y₁₂ platelets' receptor is an excellent target for developing antiplatelet agents, only five approved medications are currently in clinical use which are classified into thienopyridines and nucleoside-nucleotide derivatives. In the past years, many attempts for developing new candidates as P2Y₁₂ inhibitors have been made. This review highlights the importance and the role of P2Y₁₂ receptor as part of the coagulation cascade, its reported congenital defects, and the type of assays which are used to verify and measure its activity. Furthermore, an overview is given of the clinically approved medications, the potential naturally isolated inhibitors, and the synthesised candidates which were tested either in-vitro, in-vivo and/or clinically. Finally, we outline the in-silico attempts which were carried out using virtual screening, molecular docking and dynamics simulations in efforts of designing novel P2Y₁₂ antagonists. Various phytochemical classes might be considered as a corner stone for the discovery of novel P2Y₁₂ inhibitors, whereas a wide range of ring systems can be deliberated as leading scaffolds in that area synthetically and theoretically.

G protein-coupled purinergic P2Y receptor oligomerization: Pharmacological changes and dynamic regulation

P2Y receptors (P2YRs) are a δ group of rhodopsin-like G protein-coupled receptors (GPCRs) with many essential functions in physiology and pathology, such as platelet aggregation, immune responses, neuroprotective effects, inflammation, and cellular proliferation. Thus, they are among the most researched therapeutic targets used for the clinical treatment of diseases (e.g., the antithrombotic drug clopidogrel and the dry eye treatment drug diquafosol). GPCRs transmit signals as dimers to increase the diversity of signalling pathways and pharmacological activities. Many studies have frequently confirmed dimerization between P2YRs and other GPCRs due to their functions in cardiovascular and cerebrovascular processes in vivo and in vitro. Recently, some P2YR dimers that dynamically balance physiological functions in the body were shown to be involved in effective signal transduction and exert pathological responses. In this review, we summarize the types, pharmacological changes, and active regulators of P2YR-related dimerization, and delineate new functions and pharmacological activities of P2YR-related dimers, which may be a novel direction to improve the effectiveness of medications.

Design, synthesis and biological evaluation of novel FXIa inhibitors with 2-phenyl-1H-imidazole-5-carboxamide moiety as P1 fragment

Factor XIa, as a blood coagulation enzyme, amplifies the generation of the last enzyme thrombin in the blood coagulation cascade. It was proved that direct inhibition of factor XIa could reduce pathologic thrombus formation without an enhanced risk of bleeding. WSJ-557, a nonpurine imidazole-based xanthine oxidase inhibitor in our previous reports, could delay blood coagulation during its animal experiments, which prompted us to investigate its action mechanism. Subsequently, during the exploration of the action mechanism, it was found that WSJ-557 exhibited weak in vitro factor XIa binding affinity. Under the guide of molecular modeling, we adopted molecular hybridization strategy to develop novel factor XIa inhibitors with WSJ-557 as an initial compound. This led to the identification of the most potent compound 44g with a Ki value of 0.009 μM, which was close to that of BMS-724296 (Ki = 0.0015 μM). Additionally, serine protease selectivity study indicated that compound 44g display a desired selectivity, more 400-fold than those of thrombin, factor VIIa and factor Xa in coagulation cascade. Moreover, enzyme kinetics studies suggested that the representative compound 44g acted as a competitive-type inhibitor for FXIa, and molecular modeling revealed that it could tightly bind to the S1, S1' and S2' pockets of factor XIa. Furthermore, in vivo efficacy in the rabbit arteriovenous shunt model suggested that compound 44g demonstrated dose-dependent antithrombotic efficacy. Therefore, these results supported that compound 44g could be a potential and efficacious agent for the treatment of thrombotic diseases.