Synthesis and evaluation of NO-release from symmetrically substituted furoxans

Small-Molecule Disruptors of the Interaction between Calcium- and Integrin-Binding Protein 1 and Integrin αIIbβ3 as Novel Antiplatelet Agents

Thrombosis, a key factor in most cardiovascular diseases, is a major contributor to human mortality. Existing antithrombotic agents carry a risk of bleeding. Consequently, there is a keen interest in discovering innovative antithrombotic agents that can prevent thrombosis without negatively impacting hemostasis. Platelets play crucial roles in both hemostasis and thrombosis. We have previously characterized calcium- and integrin-binding protein 1 (CIB1) as a key regulatory molecule that regulates platelet function. CIB1 interacts with several platelet proteins including integrin αIIbβ3, the major glycoprotein receptor for fibrinogen on platelets. Given that CIB1 regulates platelet function through its interaction with αIIbβ3, we developed a fluorescence polarization (FP) assay to screen for potential inhibitors. The assay was miniaturized to 1536-well and screened in quantitative high-throughput screening (qHTS) format against a diverse compound library of 14,782 compounds. After validation and selectivity testing using the FP assay, we identified 19 candidate inhibitors and validated them using an in-gel binding assay that monitors the interaction of CIB1 with αIIb cytoplasmic tail peptide, followed by testing of top hits by intrinsic tryptophan fluorescence (ITF) and microscale thermophoresis (MST) to ascertain their interaction with CIB1. Two of the validated hits shared similar chemical structures, suggesting a common mechanism of action. Docking studies further revealed promising interactions within the hydrophobic binding pocket of the target protein, particularly forming key hydrogen bonds with Ser180. The compounds exhibited a potent antiplatelet activity based on their inhibition of thrombin-induced human platelet aggregation, thus indicating that disruptors of the CIB1- αIIbβ3 interaction could carry a translational potential as antithrombotic agents.

Tert-Butyl Nitrite-initiated C-N Bond Cleavage of 1-Nitromethyl-N-aryltetrahydroisoquinolines: Synthesis of Furoxans with N-NO Skeleton

A series of furoxan derivatives with N-nitroso groups were synthesized in good yields by TBN initiated radical sp³ C-N bond cleavage of 1-nitromethyl-N-aryltetrahydroisoquinolines. This reaction grafts the biologically important furoxan skeleton and N-nitroso group into on molecule, greatly improving the molecular complexity in one step transformation. The mechanistic study shows that this reaction is mediated by the in situ generated α-carbonyl nitrile oxide, which is afforded by TBN promoted C-N bond cleavage.

Synthesis and application of α-carbonyl nitrile oxides

A strategy has been developed to synthesize α-carbonylfuran and isoxazole using tert-butyl nitrite (TBN) as a nitrogen source.

In Vitro Metabolic Stability and in Vivo Biodistribution of 3-Methyl-4-furoxancarbaldehyde Using PET Imaging in Rats

Painful diabetic neuropathy (PDN) is a type of peripheral neuropathic pain that is currently difficult to treat using clinically available analgesics. Recent work suggests a progressive depletion of nitric oxide (NO) in nerve cells may be responsible for the pathobiology of PDN. The nitric oxide donor, 3-methyl-4-furoxancarbaldehyde (PRG150), has been shown to produce dose-dependent analgesia in a rat model of PDN. To gain insight into the mechanism of analgesia, methods to radiolabel PRG150 were developed to assess the in vivo biodistribution in rats. The furoxan ring was labeled with (13)N to follow any nitric oxide release and the 3-methyl substituent was labeled with (11)C to track the metabolite using PET imaging. The in vitro metabolic stability of PRG150 was assessed in rat liver microsomes and compared to in vivo metabolism of the synthesized radiotracers. PET images revealed a higher uptake of (13)N over (11)C radioactivity in the spinal cord. The differences in radioactive uptake could indicate that a NO release in the spinal cord and other components of the somatosensory nervous system may be responsible for the analgesic effects of PRG150 seen in the rat model of PDN.

Synthesis of Oxadiazole-2-oxide Analogues as Potential Antischistosomal Agents

The synthesis of several 1,2,5-oxadiazole-2-oxide (Furoxan) analogues is described herein. These compounds were prepared in an effort to probe the SAR around the phenyl substituent and oxadiazole core for our studies toward thioredoxin-glutathione reductase (TGR) inhibition and anti-schistosomal activity.