A panel of novel cinnamic ester derivatives showed a potent inhibitory effect against SARS-CoV-2 M ^pro and efficiently impaired the in vitro replication of two human coronaviruses in the low micromolar range.

The search for disease-modifying agents targeted against Parkinson’s disease led us to rationally design a small array of six Anle138b-centered PROTACs, 7a,b, 8a,b and 9a,b, targeting αSynuclein (αSyn) aggregates for binding, polyubiquitination by the E3 ligase Cereblon (CRBN), and proteasomal degradation. Lenalidomide and thalidomide were used as CRBN ligands and coupled with amino- and azido Anle138b derivatives through flexible linkers and coupling reactions (amidation, ‘click’ chemistry). Four Anle138b-PROTACs, 8a,b and 9a,b, were characterized against in vitro αSyn aggregation, monitoring them in a Thioflavin T (ThT) fluorescence assay and in dopaminergic neurons derived from a set of isogenic pluripotent stem cell (iPSC) lines with SNCA multiplications. Native and seeded αSyn aggregation was determined with a new biosensor, and a partial correlation between αSyn aggregation, cellular dysfunctions, and neuronal survival was obtained. Anle138b-PROTAC 8a was characterized as the most promising αSyn aggregation inhibitor/degradation inducer, with potential usefulness against synucleinopathies and cancer.

SARS-CoV-2 M^pro is a chymotrypsin-like cysteine protease playing a relevant role during the replication and infectivity of SARS-CoV-2, the coronavirus responsible for COVID-19. The binding site of M^pro is characterized by the presence of a catalytic Cys145 which carries out the hydrolytic activity of the enzyme. As a consequence, several M^pro inhibitors have been proposed to date in order to fight the COVID-19 pandemic. In our work, we designed, synthesized and biologically evaluated MPD112, a novel inhibitor of SARS-CoV-2 M^pro bearing a trifluoromethyl diazirine moiety. MPD112 displayed in vitro inhibition activity against SARS-CoV-2 M^pro at a low micromolar level (IC₅₀ = 4.1 μM) in a FRET-based assay. Moreover, an inhibition assay against PL^pro revealed lack of inhibition, assuring the selectivity of the compound for the M^pro. Furthermore, the target compound MPD112 was docked within the binding site of the enzyme to predict the established intermolecular interactions in silico. MPD112 was subsequently tested on the HCT-8 cell line to evaluate its effect on human cells’ viability, displaying good tolerability, demonstrating the promising biological compatibility and activity of a trifluoromethyl diazirine moiety in the design and development of SARS-CoV-2 M^pro binders.