One-pot synthesis of α-aminophosphonates by yttrium-catalyzed Birum-Oleksyszyn reaction

Chemically diverse activity-based probes with unexpected inhibitory mechanisms targeting trypsin-like serine proteases

Activity-based probes (ABP) are molecules that bind covalently to the active form of an enzyme family, making them an attractive tool for target and biomarker identification and drug discovery. The present study describes the synthesis and biochemical characterization of novel activity-based probes targeting trypsin-like serine proteases. We developed an extensive library of activity-based probes with "clickable" affinity tags and a diaryl phosphonate warhead. A wide diversity was achieved by including natural amino acid analogs as well as basic polar residues as side chains. A detailed enzymatic characterization was performed in a panel of trypsin-like serine proteases. Their inhibitory potencies and kinetic profile were examined, and their IC₅₀ values, mechanism of inhibition, and kinetic constants were determined. The activity-based probes with a benzyl guanidine side chain showed the highest inhibitory effects in the panel. Surprisingly, some of the high-affinity probes presented a reversible inhibitory mechanism. On the other hand, probes with different side chains exhibited the expected irreversible mechanism. For the first time, we demonstrate that not only irreversible probes but also reversible probes can tightly label recombinant proteases and proteases released from human mast cells. Even under denaturing SDS-PAGE conditions, reversible slow-tight-binding probes can label proteases due to the formation of high-affinity complexes and slow dissociation rates. This unexpected finding will transform the view on the required irreversible nature of activity-based probes. The diversity of this library of activity-based probes combined with a detailed enzyme kinetic characterization will advance their applications in proteomic studies and drug discovery.

Improved Synthesis of the Selected Serine Protease uPA Inhibitor UAMC-00050, a Lead Compound for the Treatment of Dry Eye Disease

The α-aminophosphonate UAMC-00050, a newly developed trypsin-like serine protease inhibitor, is a lead compound for the treatment of dry eye syndrome and ocular inflammation. The medicinal chemistry route developed at the University of Antwerp possessed several problems hampering the scale-up such as poor yields for some of the steps, hazardous reagents, and environmental footprint. Herein, we report an optimized route for the UAMC-00050, in which environmental unfriendly solvents were excluded, hazardous reagents were replaced with safer alternatives, and are more efficient in terms of atom economy. Every reaction step was optimized to reach a higher yield, and design of experiment was used to find the optimum conditions in the last step. Furthermore, all the flash chromatography purifications of intermediates were replaced with plug filtration, slurry purifications, or crystallization. The overall yield was increased from 3% in the medicinal chemistry route to 22% in the process development route.