2-Imidazole as a Substitute for the Electrophilic Group Gives Highly Potent Prolyl Oligopeptidase Inhibitors

Abstract

Different five-membered nitrogen-containing heteroaromatics in the position of the typical electrophilic group in prolyl oligopeptidase (PREP) inhibitors were investigated and compared to tetrazole. The 2-imidazoles were highly potent inhibitors of the proteolytic activity. The binding mode for the basic imidazole was studied by molecular docking as it was expected to differ from the acidic tetrazole. A new putative noncovalent binding mode with an interaction to His680 was found for the 2-imidazoles. Inhibition of the proteolytic activity did not correlate with the modulating effect on protein–protein-interaction-derived functions of PREP (i.e., dimerization of alpha-synuclein and autophagy). Among the highly potent PREP inhibiting 2-imidazoles, only one was also a potent modulator of PREP-catalyzed alpha-synuclein dimerization, indicating that the linker length on the opposite side of the molecule from the five-membered heteroaromatic is critical for the disconnected structure–activity relationships.

Nonpeptidic Oxazole-Based Prolyl Oligopeptidase Ligands with Disease-Modifying Effects on α-Synuclein Mouse Models of Parkinson’s Disease

“…To study the effect of compounds on early phases of αSyn aggregation, αSyn dimerization was assessed by a PCA that has been described in the study by Savolainen et al and used by us in several studies. ,, Briefly, N2A cells were seeded on 96-well plates (Isoplate white wall, PerkinElmer Life Sciences) at a density of 13,000 cells/well and transfected with 25 ng of both αSyn-Gluc1 and αSyn-Gluc2 or 50 ng mock plasmid as a control by using Lipofectamine 3000 (L3000001; ThermoFisher Scientific) as the transfection reagent. Forty-eight hours post-transfection, cells were incubated for 4 h with study compounds (10 μM) in DMEM without phenol red (11039021; ThermoFisher Scientific).…”

“…6,10,23 By studying different PREP inhibitors, we have demonstrated that the structure−activity relationships (SARs) for inhibition of the proteolytic activity and modulation of PPImediated functions, αSyn dimerization and autophagy, are disconnected in the way that some weak PREP inhibitors are highly effective modulators of the PPIs and some highly potent inhibitors do not affect the PPIs at all. 17,24,25 In an αSyndimerization assay performed with PREP knock-out (PREP-KO) cells, the effect of all PREP inhibitors on αSyn dimerization was lost, demonstrating that their effect is the result of an interaction with PREP. 17 As PREP is a highly dynamic protein and inhibitor binding has been reported to restrict its conformational freedom, 26,27 our hypothesis is that the functions of PREP are dependent on what conformations PREP can adopt, and these dynamic features can be regulated differently by different ligands.…”

Inhibition-mediated changes in prolyl oligopeptidase dynamics possibly related to α-synuclein aggregation

“…8,9,11 Remarkably, experimental studies of PREP suggest that not all PREP inhibitors affect syneculein aggregation at the same level. 12,13…”

“…24–26 They differ in the way of binding (KYP 2047 binds covalently to PREP, whereas SUAM 1221 and S 17 092 do not) and inhibition efficacy (KYP 2047 is a potent inhibitor, whereas S 17 092 and SUAM 1221 are weak inhibitors with the IC 50 values 0.2 nM, 27 1.5 nM, 26 and 2.0 nM, 28 respectively). 12,13 More importantly, it has been shown that these inhibitors differently affect dimerisation of α-synuclein – 25%, 20% and the lack of reduction of α-synucleins interaction. 12…”

Multicomponent Cascade Reaction of 3-Cyanochromones: Highly Site-Selective Synthesis of 2-(1H-Imidazol-1-yl)-4H-chromen-4-one Derivatives

“…Imidazoles are also privileged heterocyclic rings that are ubiquitous throughout natural and synthetic compounds, many of which boast a variety of biological activities (Figure ), including antitumor (Compound A), antiviral, anti-HIV (Compound B), antibacterial, and anti-inflammatory (SB216995), by acting as inhibitors of Bruton’s tyrosine kinase (BTK), prolyl oligopeptidase (PREP), and other enzymes. For example, temozolomide and nilotinib have been approved for use to treat cancer; losartan and losartan hydrochlorothiazide are marketed antihypertensive drugs; ketoconazole, miconazole, econazole, and clotrimazole are well-known antifungal agents; and metronidazole, ornidazole, tinidazole, and secnidazole are anti-infective agents used to treat various bacterial and protozoan infections.…”