Design, parallel synthesis, and crystal structures of pyrazinone antithrombotics as selective inhibitors of the tissue factor VIIa complex
Research article published in Journal of medicinal chemistry (2003)
Abstract
Structure-based drug design (SBDD) and polymer-assisted solution-phase (PASP) library synthesis were used to develop a series of pyrazinone inhibitors of the Tissue Factor/Factor VIIa (TF/VIIa) complex. The crystal structure of a tripeptide-alpha-ketothiazole complexed with TF/VIIa was utilized in a docking experiment to identify the pyrazinone core as a starting scaffold. The pyrazinone core could orient the substituents in the correct spatial arrangement to probe the S1, S2, and S3 pockets of the enzyme. A multistep PASP library synthesis was designed to prepare the substituted pyrazinones varying the P1, P2, and P3 moieties. Hundreds of pyrazinone TF/VIIa inhibitors were prepared and tested in several serine protease enzyme assays involved in the coagulation cascade. The inhibitors exhibited modest activity on TF/VIIa with excellent selectivity over thrombin (IIa) and Factor Xa. The structure-activity relationship of the pyrazinone inhibitors will be discussed and X-ray crystal structures of selected compounds complexed with the TF/VIIa enzyme will be described. This study ultimately led to the synthesis of compound 34, which exhibited 16 nM (IC50) activity on TF/VIIa with >6250 x selectivity vs Factor Xa and thrombin. This potent and highly selective inhibitor of TF/VIIa was chosen for preclinical, intravenous proof-of-concept studies to demonstrate the separation between antithrombotic efficacy and bleeding side effects in a nonhuman primate model of electrolytic-induced arterial thrombosis.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Summary
Peer-reviewed research on therapeutic compound development relevant to leech-derived anticoagulants and antithrombotic agents. Indexed in PubMed and verified against the NCBI record.
Why This Matters for Hirudotherapy
This drug-design study used structure-based design and polymer-assisted solution-phase library synthesis to build pyrazinone inhibitors of the Tissue Factor/Factor VIIa (TF/VIIa) coagulation-cascade complex, using a crystal-structure docking experiment to identify the pyrazinone core and synthesizing and testing hundreds of analogs in serine-protease coagulation assays; while the series showed modest TF/VIIa activity with excellent selectivity, it ultimately yielded compound 34, a potent (16 nM IC50) and highly selective TF/VIIa inhibitor (>6250-fold over factor Xa and thrombin) selected for intravenous preclinical proof-of-concept in a nonhuman-primate electrolytic-induced arterial-thrombosis model to probe the separation of antithrombotic efficacy from bleeding. It connects to the leech-secretome narrative by exemplifying rational antithrombotic drug discovery targeting the coagulation cascade, the same broad pathway that medicinal-leech salivary proteins (hirudin, factor Xa inhibitors, and others) modulate, underscoring why characterizing the leech secretome is a credible source of selective anticoagulant leads. Caveat: this is preclinical medicinal chemistry with in-vitro enzyme assays, crystallography, and only planned/early animal proof-of-concept; the compounds are synthetic, not leech-derived, and the work makes no clinical efficacy or safety claims in humans.
Citation
Design, parallel synthesis, and crystal structures of pyrazinone antithrombotics as selective inhibitors of the tissue factor VIIa complex.
Parlow JJ et al. · Journal of medicinal chemistry, 2003
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