Prolyl Oligopeptidase Research Articles

Neuroinflammatory Response and Redox-regulation Activity of Hyperoside in Manganese-induced Neurotoxicity Model of Wistar Rats.

Excessive manganese exposure can lead to neurotoxicity with detrimental effects on the brain. Neuroinflammatory responses and redox regulation play pivotal roles in this process. Exploring the impact of hyperoside in a Wistar rat model offers insights into potential neuroprotective strategies against manganese-induced neurotoxicity. The study investigated the neuroprotective efficacy of hyperoside isolated from the ethanol leaf extract of Gongronema latifolium (HELEGL), in the brain tissue of Wistar rats following 15 consecutive days of exposure to 30 mg/L of MnCl2. Control animals in Group 1 had access to regular drinking water, while animals in groups 2-4 were exposed to MnCl2 in their drinking water. Groups 3 and 4 also received additional HELEGL at doses of 100 mg/kg and 200 mg/kg of body weight, respectively. In Group 5, HELEGL at a dose of 100 mg/kg of body weight was administered alone. Treatment with HELEGL commenced on day 8 via oral administration. HELEGL effectively mitigated MnCl2-induced memory impairment, organ-body weight discrepancies, and fluid intake deficits. Exposure to MnCl2 increased the activities or levels of various markers such as acyl peptide hydrolase, tumour necrosis factor-α, dipeptidyl peptidase IV, nitric oxide, IL-1β, prolyl oligopeptidase, caspase-3, myeloperoxidase, H2O2, and malondialdehyde, while it decreased the activities or levels of others, including AChE, BChE, DOPA, serotonin, epinephrine, norepinephrine, GST, GPx, CAT, SOD, GSH, and T-SH (p < 0.05). In contrast, HELEGL effectively counteracted the adverse effects of MnCl2 by alleviating oxidative stress, inflammation, apoptosis, mitochondrial dysfunction, cognitive deficits, and bolstering the antioxidant status. Moreover, HELEGL restored the normal histoarchitecture of the brain, which had been distorted by MnCl2. In summary, HELEGL reversed the causative factors of neurodegenerative diseases induced by MnCl2 exposure, suggesting its potential for further exploration as a prospective therapeutic agent in the management of Alzheimer's disease and related forms of dementia.

Synthesis of 2,4-Bis(trifluoromethyl)benzaldehyde Hybrid Thiosemicarbazones as Prolyl Oligopeptidase Inhibitors for Neurodegenerative Disorders and their In-silico Analysis.

Prolyl-specific oligopeptidase (POP), one of the brain's highly expressed enzymes, is an important target for the therapy of central nervous system disorders, notably autism spectrum disorder, schizophrenia, Parkinson's, Alzheimer's disease, and dementia. The current study was designed to investigate 2,4-bis(trifluoromethyl) benzaldehyde- based thiosemicarbazones as POP inhibitors to treat the above-mentioned disorders. A variety of techniques, such as nuclear magnetic resonance (NMR), mass spectrometry (MS), and Fourier-transform infrared spectroscopy (FTIR), were used for the structural confirmation of synthesized compounds. After in-vitro evaluation, all of these compounds were found to be prominent inhibitors of the POP enzyme (IC50= 10.14 - 41.73 μM). Compound 3a emerged as the most active compound (IC50 10.14 ± 0.72 μM) of the series. The kinetic study of the most active 3a (Ki =13.66 0.0012 μM) indicated competitive inhibition of the aforementioned enzyme. Moreover, molecular docking depicted a noticeable role of thiosemicarbazide moiety in the binding of these molecules within the active site of the POP enzyme.

Structural adaptations for carboxypeptidase activity in putative S9 acylaminoacyl peptidase from Bacillus subtilis

Prolyl oligopeptidase, or S9 (MEROPS) family enzymes are crucial drug targets due to their association with various diseases, neurological disorders, cell growth, and survival. These implications render them an exceptionally fascinating field of research. Despite sharing similar structural features, they exhibit diverse enzyme activities, including endopeptidase, dipeptidyl peptidase, and acylaminoacyl peptidase. Additionally, a few members of the S9 family demonstrate carboxypeptidase activity. A recent study showed that the S9 peptidase of Bacillus subtilis (S9bs) possesses the conserved sequence feature necessary for carboxypeptidase activity despite being annotated as an acylaminoacyl peptidase in the UniProt database. However, the mechanism of action and identity of S9bs as carboxypeptidase remain unclear. Consequently, we focused our studies on thoroughly investigating S9bs for its carboxypeptidase activity. In the present study, we report biochemical and biophysical analyses of S9bs, confirming its identity as a carboxypeptidase. Further, structural analysis reveals the molecular basis of S9bs' carboxypeptidase activity, highlighting the crucial structural elements like the “cavity loop” and the “two-arginine” residues essential for this activity. Additionally, our studies confirmed that S9bs forms a stable tetrameric assembly and established its quaternary molecular arrangement, which reveals the presence of an oligomeric pore. Altogether, these structural features play a are crucial role in substrate selection for S9 carboxypeptidases. Overall, our findings reveal a distinct carboxypeptidase within the S9 family and significantly enhance our understanding of these enzymes. Moreover, this study sheds light on the mechanisms underlying carboxypeptidase activity, offering valuable insights that could contribute to therapeutic and drug design.

Morpholine-tethered Novel Hydrazones as Promising Non-peptidic Prolyl Oligopeptidase (POP) Inhibitors: Synthesis In Vitro and In Silico Studies.

Prolyl oligopeptidase (POP) is a pivotal druggable target implicated in diverse biological processes and linked to the development of various ailments, including neurodegenerative disorders. While conventional peptide-based inhibitors have been a centerpiece, their limitations, such as restricted bioavailability, necessitate exploration of non-peptidic inhibitors for their therapeutic potential. This study focuses on designing, synthesizing, and assessing morpholine-based hydrazones targeting the catalytic serine residue of POP. The hydrazones (5a-o), reported as moderately potent analogs compared to the renowned Z-Pro-Prolinal, demonstrated in vitro POP inhibition with IC50 values ranging from 13.60 ± 2.51 to 36.51 ± 1.82 μM. The derivative 5h, with an IC50 of 13.60 ± 2.51 μM, emerged as the most potent inhibitor. Moreover, the in vitro kinetic study of compound 5h indicated that it exhibited concentration-dependent type of inhibition. in silico docking studies of 5h revealed robust interactions in the POP enzyme's active site, yielding a docking score of -6.30 Kcal/- mol, consistent with experimental results. All findings underscored the potential of synthesized derivatives for drug development.

Synthesis of Novel Benzimidazole Analogs for Neurodegenerative Diseases by Targeting Prolyl Oligopeptidase

AbstractA novel series of benzimidazole hydrazone‐Schiff bases have been prepared through multi‐step reaction process and structurally confirmed by13C‐,1H‐NMR and HR‐MS (ESI) spectroscopic techniques and evaluated against prolyl oligopeptidase (POP) inhibitory activity. In the series, eleven derivatives 20, 14 15, 19, 10, 9, 11, 4, 5, 18, and 21 revealed excellent inhibition potential having IC50 values from (IC50=1.44±0.08 μM) to (IC50=5.66±0.48 μM). However, six out of twenty compounds 12, 16, 13, 17, 22, and 3 attributed significant activity while, three compounds were found good active in the range of IC50 values 10.43±0.57 to 11.45±0.63 μM. The docking studies indicates that the hydrazone moiety show an imperative part in binding with one of the catalytic residues (Arg643) in the substrate binding region of POP enzyme. The excellent inhibitions of these compounds for POP enzyme may lead them to be a good candidates for drug against neurodegenerative diseases.

Structural visualization of inhibitor binding in prolyl oligopeptidase.

The association and dissociation of proteins and ligands are crucial in biophysics for potential drug development [Baron and McCammon, Annu. Rev. Phys. Chem. 64, 151-175 (2013)]. However, identifying and characterizing the reaction pathways for these rare events has been a long-standing challenge. Molecular dynamics (MD) simulations are limited in exploring biophysical processes on experimental timescales, so ligand transport processes through complex transient tunnels formed by proteins during dynamics are often simulated using enhanced sampling MD [Rydzewski and Nowak, Phys. Life Rev. 22-23, 58-74 (2017)]. Erroneously identified ligand binding pathways can affect thermodynamic and kinetic characteristics calculated from MD trajectories. A system that has the potential to be a therapeutic target for neurodegenerative diseases is prolyl oligopeptidase (PREP). This is due to its involvement in promoting protein aggregation and disrupting cellular function through affecting protein-protein interactions (PPI). The recent discovery of a new type of PREP inhibitor that targets PPI raises important questions about the diversity of ligand binding pathways in PREP and their impact on protein dynamics [Pätsi et al., J. Med. Chem. 67, 5421-5436 (2024); Kilpeläinen et al., J. Med. Chem. 66, 7475-7496 (2023); and Walczewska-Szewc et al., Phys. Chem. Chem. Phys. 24, 4366-4373 (2022)]. In this article, using results from enhanced sampling MD, we visually present how the binding process in PREP depends on subtle changes in inhibitors, which could be crucial in treating neurodegenerative disorders.

Potent Small Molecules Inhibitors Discovery through Ligand-based Modelling for Effective Treatment of Parkinson’s Disease

Background: Parkinson’s disease (PD) is a chronic neurodegenerative disease affecting mostly aged people. The disease's symptoms develop gradually over time and include tremors, bradykinesia, rigidity, and postural instability. Current treatment options for PD are only symptom-targeted. Prolyl oligopeptidase (POP) is a serine protease enzymes implicated in PD pathogenesis via an increase in the aggregation of α-synuclein protein in the brain. Aim: This study aims to identify potent anti-PD ligands with inhibitory potential against POP Methods: Ligand-based pharmacophore modeling, Glide extra precision (XP) docking, and post-simulation analysis methods were used. Results: The adopted ligand-based (LB) modeling generated pharmacophoric features, including 1 hydrophobic group, 1 positive ionizable group, 2 aromatic rings, and 2 hydrogen bond acceptors. A total of 23 hits with a Gunner-Henry score of 0.7 and an enrichment factor of 30.24 were obtained as validation protocols, making it an ideal model. The LB model retrieved 177 hit compounds from the 69,543 natural screening ligands available in the Interbioscreen database. Interestingly, ligands 1, 2, 3, 4, and 5 orderly demonstrated higher binding affinities with Glide XP docking of -9.0, -8.8, -8.7, -8.7, -8.7 kcal/mol compared to reference drugs, GSK552 and ZPP with -8.2, and -6.8 kcal/mol respectively. Similarly, their MM/GBSA values were recorded as -54.4, -51.3, -58.4, -49.3, - 33.5, &amp; -32.5 kJ/mol respectively. Further, MD analysis indicated that ligands had higher favorable binding and stability to the receptor. Conclusion: Overall, the study paves the way for developing potential anti-PD therapeutics. The ligands are recommended as adjuvant/single candidate as anti-PD candidates upon further experiment.

Gene cloning, IPTG-independent auto-induction and characterization of a novel hyperstable S9 prolyl oligopeptidase having lipolytic activity from Thermotoga naphthophila RKU-10T with applications

A hyperstable lipase from Thermotoga naphthophila (TnLip) was cloned and overexpressed as a soluble and active monomeric protein in an effectual mesophilic host system. Sequence study revealed that TnLip is a peptidase S9 prolyl oligopeptidase domain (acetyl esterase/lipase-like protein), belongs to alpha/beta (α/β)-hydrolase superfamily containing a well-conserved α/β-hydrolase fold and penta-peptide (GLSAG) motif. Various cultivation and induction strategies were applied to improve the heterologous expression and bacterial biomass, but TnLip intracellular activity was enhanced by 14.25- fold with IPTG-independent auto-induction approach after 16 h (26 °C, 150 rev min−1) incubation. Purified TnLip (35 kDa) showed peak activity at 85 °C in McIlvaine buffer (pH 7.0–8.0), and has great stability over a broad range of pH (5.0–10.0), and temperature (40–85 °C) for 8 h. TnLip exhibited prodigious resistance toward various commercial detergents, chemical additives, and salt. TnLip activity was improved by 170.51 %, 130.67 %, 127.42 %, 126.54 %, 126.61 %, 120.32 %, and 116.31 % with 50 % (v/v) of methanol, ethanol, n-butanol, isopropanol, acetone, glycerol, and acetic acid, respectively. Moreover, with 3.0 M of NaCl, and 10 mM of Ca2+, Mn2+, and Mg2+ TnLip activity was augmented by 210 %, 185.64 %, 152.03 %, and 116.26 %, respectively. TnLip has an affinity with various substrates (p-nitrophenyl ester and natural oils) but maximal hydrolytic activity was perceived with p-nitrophenyl palmitate (pNPP, 3600 U mg−1) and olive oil (1182.05 U mg−1). The values of Km (0.576 mM), Vmax (4216 μmol mg−1 min−1), VmaxKm−1 (7319.44 min−1), kcat (1106.74 s−1), and kcatKm−1 (1921.42 mM−1 s−1) were calculated using pNPP substrate. Additionally, TnLip degraded animals' fats and removed oil stains within 3 h and 5 min, respectively. All these features make halo-alkali-thermophilic TnLip as an auspicious contender for laundry detergents (cleaning bio-additive), fat degradation, wastewater treatment and endorse eco-friendly stewardship along with various other biotechnological applications.

Synthesis, biological evaluation, and molecular modelling of substituted thiazolyl thiourea derivatives: A new class of prolyl oligopeptidase inhibitors

Prolyl oligopeptidase (POP) is a compelling therapeutic target associated with aging and neurodegenerative disorders due to its pivotal role in neuropeptide processing. Despite initial promise demonstrated by early-stage POP inhibitors, their progress in clinical trials has been halted at Phase I or II. This impediment has prompted the pursuit of novel inhibitors. The current study seeks to contribute to the identification of efficacious POP inhibitors through the design, synthesis, and comprehensive evaluation (both in vitro and in silico) of thiazolyl thiourea derivatives (5a-r). In vitro experimentation exhibited that the compounds displayed significant higher potency as POP inhibitors. Compound 5e demonstrated an IC50 value of 16.47 ± 0.54 μM, representing a remarkable potency. A meticulous examination of the structure-activity relationship indicated that halogen and methoxy substituents were the most efficacious. In silico investigations delved into induced fit docking, pharmacokinetics, and molecular dynamics simulations to elucidate the intricate interactions, orientation, and conformational changes of these compounds within the active site of the enzyme. Moreover, our pharmacokinetic assessments confirmed that the majority of the synthesized compounds possess attributes conducive to potential drug development.

Design of a Fibroblast Activation Protein-Targeted Radiopharmaceutical Therapy with High Tumor-to-Healthy-Tissue Ratios.

Because of upregulated expression on cancer-associated fibroblasts, fibroblast activation protein (FAP) has emerged as an attractive biomarker for the imaging and therapy of solid tumors. Although many FAP ligands have already been developed for radiopharmaceutical therapies (RPTs), most suffer from inadequate tumor uptake, insufficient tumor residence times, or off-target accumulation in healthy tissues, suggesting a need for further improvements. Methods: A new FAP-targeted RPT with a novel ligand (FAP8-PEG3-IP-DOTA) was designed by combining the desirable features of several previous ligand-targeted RPTs. Uptake and retention of [111In]In or [177Lu]Lu-FAP8-PEG3-IP-DOTA were assessed in KB, HT29, MDA-MB-231, and 4T1 murine tumor models by radioimaging or ex vivo biodistribution analyses. Radiotherapeutic potencies and gross toxicities were also investigated by monitoring tumor growth, body weight, and tissue damage in tumor-bearing mice. Results: FAP8-PEG3-IP-DOTA exhibited high affinity (half-maximal inhibitory concentration, 1.6 nM) and good selectivity for FAP relative to its closest homologs, prolyl oligopeptidase (half-maximal inhibitory concentration, ∼14.0 nM) and dipeptidyl peptidase-IV (half-maximal inhibitory concentration, ∼860 nM). SPECT/CT scans exhibited high retention in 2 different solid tumor models and minimal uptake in healthy tissues. Quantitative biodistribution analyses revealed tumor-to-healthy-tissue ratios of more than 5 times for all major organs, and live animal studies demonstrated 65%-93% suppression of tumor growth in all 4 models tested, with minimal or no evidence of systemic toxicity. Conclusion: We conclude that [177Lu]Lu-FAP8-PEG3-IP-DOTA constitutes a promising and safe RPT candidate for FAPα-targeted radionuclide therapy of solid tumors.

Identification of DPP-IV inhibitory peptides derived from buffalo colostrum: Mining through bioinformatics, in silico and in vitro approaches.

Bioactive peptides derived from foods provide physiological health benefits beyond nutrition. This study focused on profiling small peptide inhibitors against two key serine proteases, dipeptidyl peptidase-IV (DPP-IV) and prolyl oligopeptidase (POP). DPP-IV is a well-known protein involved in diverse pathways regulating inflammation, renal, cardiovascular physiology, and glucose homeostasis. POP is yet another key target protein for neurodegenerative disorders. The study evaluated peptide libraries of buffalo colostrum whey and fat globule membrane proteins derived from pepsin and pepsin-pancreatin digestion through in silico web tools and structure-based analysis by molecular docking and binding free-energy estimation, followed by in vitro assay for DPP-IV inhibition for the lead peptides. The bioinformatic study indicated 49 peptides presented motifs with DPP-IV inhibition while 5 peptides with sequences for POP inhibition. In the molecular docking interactions study, 22 peptides interacted with active site residues of DPP-IV and 3 peptides with that of POP. The synthesized peptides, SFVSEVPEL and LTFQHNF inhibited DPP-IV in vitro with an IC50 of 193.5 μM and 1.782 mM, respectively. The study revealed the key residues for inhibition of DPP-IV and POP thus affirming the DPP-IV inhibitory potential of milk-derived peptides.

Study of the Conformational Dynamics of Prolyl Oligopeptidase by Mass Spectrometry: Lessons Learned.

Ion mobility mass spectrometry (IM-MS) can be used to analyze native proteins according to their size and shape. By sampling individual molecules, it allows us to study mixtures of conformations, as long as they have different collision cross sections and maintain their native conformation after dehydration and vaporization in the mass spectrometer. Even though conformational heterogeneity of prolyl oligopeptidase has been demonstrated in solution, it is not detectable in IM-MS. Factors that affect the conformation in solution, binding of an active site ligand, the stabilizing Ser554Ala mutation, and acidification do not qualitatively affect the collision-induced unfolding pattern. However, measuring the protection of accessible cysteines upon ligand binding provides a principle for the development of MS-based ligand screening methods.

Indole-based thiosemicarbazones for neurodegenerative diseases as prolyl oligopeptidase inhibitors

One of the highly expressed enzymes in the brain, prolyl specific oligopeptidase (POP), is a key target for the treatment of illnesses of the central nervous system including, autism spectrum, schizophrenia, Parkinson's, dementia, and Alzheimer's. In the current studies we report a series of indole based thiosemicarbazone as prolyl oligopeptidase (POP) inhibitors. Numerous approaches, such as Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and mass-spectrometry (MS) procedures, were used to confirm the structures of all substances. These compounds were evaluated against POP interestingly all these tested molecules significantly inhibit POP in vitro at very low doses (5.74–25.30 µM). Compound 3g displayed the highest inhibition with IC50 value 5.74 ± 0.27 µM. Kinetic studies of compounds, 3g, revealed concentration dependent type of inhibition with Ki value 4.31 ± 0.0012 µM. Furthermore, molecular docking was also performed to understand the binding modes of compounds, which correlates with our in vitro outcomes.

Angiotensin-(1-12): Does It Exist? A Critical Evaluation in Humans, Rats, and Mice.

Angiotensin-(1-12), measured by a self-developed, polyclonal antibody-based radioimmunoassay, has been suggested to act as an alternative precursor of angiotensin II. A more reliable detection method would be liquid chromatography-tandem mass spectrometry. We set up the quantification of human and murine angiotensin-(1-12) by liquid chromatography-tandem mass spectrometry and then used this method to measure angiotensin-(1-12) in human, rat, and mouse blood samples, as well as in mouse brain, mouse kidney, and rat heart. We also verified ex vivo angiotensin-(1-12) generation and metabolism in human blood samples incubated at 37 °C. Stabilization of blood in guanidine hydrochloride was chosen for sample collection since this allowed full recovery of spiked angiotensin-(1-12). Angiotensin-(1-12) was undetectable in human blood samples when incubating nonstabilized plasma at 37 °C, while angiotensin-(1-12) added to nonstabilized human plasma disappeared within 10 minutes. Stabilized human blood samples contained angiotensin II, while angiotensin-(1-12) was undetectable. Blood, hearts, and kidneys, but not brains, of wild-type mice and rats contained detectable levels of angiotensin II, while angiotensin-(1-12) was undetectable. In renin knockout mice, all angiotensins, including angiotensin-(1-12), were undetectable at all sites, despite a 50% rise in angiotensinogen. Angiotensin-(1-12) metabolism in human blood plasma was not affected by renin inhibition. Yet, blockade of angiotensin-converting enzyme and aminopeptidase A, but not of chymase, neutral endopeptidase, or prolyl oligopeptidase, prolonged the half-life of angiotensin-(1-12), and angiotensin-converting enzyme inhibition prevented the formation of angiotensin II. We were unable to detect intact angiotensin-(1-12) in humans, rats, and mice, either in blood or tissue, suggesting that this metabolite is an unlikely source of endogenous angiotensins.

5-Aminothiazoles Reveal a New Ligand-Binding Site on Prolyl Oligopeptidase Which is Important for Modulation of Its Protein-Protein Interaction-Derived Functions.

A series of novel 5-aminothiazole-based ligands for prolyl oligopeptidase (PREP) comprise selective, potent modulators of the protein-protein interaction (PPI)-mediated functions of PREP, although they are only weak inhibitors of the proteolytic activity of PREP. The disconnected structure-activity relationships are significantly more pronounced for the 5-aminothiazole-based ligands than for the earlier published 5-aminooxazole-based ligands. Furthermore, the stability of the 5-aminothiazole scaffold allowed exploration of wider substitution patterns than that was possible with the 5-aminooxazole scaffold. The intriguing structure-activity relationships for the modulation of the proteolytic activity and PPI-derived functions of PREP were elaborated by presenting a new binding site for PPI modulating PREP ligands, which was initially discovered using molecular modeling and later confirmed through point mutation studies. Our results suggest that this new binding site on PREP is clearly more important than the active site of PREP for the modulation of its PPI-mediated functions.

Novel hydrazone schiff’s base derivatives of polyhydroquinoline: synthesis, in vitro prolyl oligopeptidase inhibitory activity and their Molecular docking study

This research work reports the synthesis of new derivatives of the hydrazone Schiff bases (1–17) based on polyhydroquinoline nucleus through multistep reactions. HR-ESIMS,1H- and 13C-NMR spectroscopy were used to structurally infer all of the synthesized compounds and lastly evaluated for prolyl oligopeptidase inhibitory activity. All the prepared products displayed good to excellent inhibitory activity when compared with standard z-prolyl-prolinal. Three derivatives 3, 15 and 14 showed excellent inhibition with IC50 values 3.21 ± 0.15 to 5.67 ± 0.18 µM, while the remaining 12 compounds showed significant activity. Docking studies indicated a good correlation with the biochemical potency of compounds estimated in the in-vitro test and showed the potency of compounds 3, 15 and 14. The MD simulation results confirmed the stability of the most potent inhibitors 3, 15 and 14 at 250 ns using the parameters RMSD, RMSF, Rg and number of hydrogen bonds. The RMSD values indicate the stability of the protein backbone in complex with the inhibitors over the simulation time. The RMSF values of the binding site residues indicate that the potent inhibitors contributed to stabilizing these regions of the protein, through formed stable interactions with the protein. The Rg. analysis assesses the overall size and compactness of the complexes. The maintenance of stable hydrogen bonds suggests the existence of favorable binding interactions. SASA analysis suggests that they maintained stable conformations without large-scale exposure to the solvent. These results indicate that the ligand–protein interactions are stable and could be exploited to design new drugs for disease treatment. Communicated by Ramaswamy H. Sarma

Ex vivo degradation of β-Casomorphin-7 by human plasma peptidases: Potential implications for peptide systemic effects

Susceptibility to proteolytic activity is a critical limitation for food-derived peptides possibly influencing human physiological processes. This study explores the ex vivo stability and degradation kinetics of the milk-derived opioid peptide β-casomorphin-7 (BCM7) in human blood. Blood specimens collected from three healthy volunteers were individually spiked with synthetic BCM7 and sampled at seven time points over 2 h. Liquid chromatography-electrospray-high resolution tandem mass spectrometry was used to monitor the stability of BCM7 and the formation of its hydrolytic fragments. Human plasma peptidases rapidly hydrolyzed BCM7 generating inactive peptides with similar sharp degradation kinetics across the blood of different individuals. The estimated plasma half-life (t1/2) value of BCM7 ranged from 35 to 40 min. The peptide degradation pattern pointed to prolyl oligopeptidase, prolidase, and dipeptidyl peptidase as the primary enzyme candidates responsible for BCM7 hydrolysis. Overall, the findings of this study suggest that BCM7 cannot exert systemic effects in humans.

Novel benzimidazole derivatives as effective inhibitors of prolyl oligopeptidase: synthesis, in vitro and in silico analysis.

Background: This research aims to discover novel derivatives having potential therapeutic applications in treating conditions related to prolyl oligopeptidase (POP) dysfunction. Method: Novel benzimidazole derivatives have been synthesized, characterized and screened for their in vitro POP inhibition. Results: All these derivatives showed excellent-to-good inhibitory activities in the range of IC50 values of 3.61±0.15to 43.72±1.18μM, when compared with standard Z-prolyl-prolinal. The docking analysis revealed the strong interactions between our compounds and the target enzyme, providing critical insights into their binding affinities and potential implications for drug development. Conclusion: The significance of these compounds in targeting POP enzymeoffers promising prospects for future research in the field of neuropharmacology.

Novel Small‐Molecular Ligands for Prolyl Oligopeptidase to Combat Tauopathies

AbstractBackgroundTauopathies that include e.g. frontotemporal dementia and Alzheimer’s disease, are neurodegenerative diseases characterized by accumulation of hyperphosphorylated Tau in the brain. Tau is a tempting drug target for tauopathies but no Tau‐targeting therapies are in clinical use. We have recently shown that small‐molecular inhibitors of prolyl oligopeptidase (PREP) can activate protein phosphatase 2A (PP2A) by regulating PREP‐PP2A interaction. PP2A is the main phosphatase regulating Tau, and therefore, we decided to test the efficacy of a reference PREP inhibitor, KYP‐2047, and novel PREP ligands on cellular and animal models of tauopathies.MethodThe compounds, KYP‐2047 and HUP‐46, 55 and 59 (1, 5 and 10 μM), were first screened in the GFP‐2N4R‐Tau transfected HEK‐293 cells where the Tau aggregation was induced by small‐dose okadaic acid (OA; 10 nM), a PP2A inhibitor. The results were verified by using 2N4R‐Tau transfected HEK‐293 cells with 10 nM OA. After the treatment the cells were fractioned to RIPA soluble and SDS‐fractions, and total Tau and S262 phosphorylated Tau (pS262 Tau) levels were studied by Western blot (WB). Finally, KYP‐2047 and HUP‐46 were tested in PS19 Tau transgenic mouse. PS19 mice were treated with the ligands for 4 weeks (10 mg/kg/day, Alzet minipump i.p.) starting from 5.5 months old when the behavioral deficits were observed. After the treatment, the mice behavior was tested by Barnes Maze and locomotor activity assay, and total Tau, pS262 Tau and PP2A levels were studied.ResultIn the GFP‐Tau aggregation assay, all compounds decreased the GFP signal as an indicative of Tau aggregation with 10 mM concentration but HUP‐46 was the most effective (Fig. 1). WB that showed that PREP ligands had the most significant effect on total Tau and pS262 Tau in the SDS‐fraction. In the PS19 mice, KYP‐2047 restored normal behavior in Barnes maze and locomotor activity assay. HUP‐46 had similar effect but did not reach significance (Fig. 2). However, both compounds reduced significantly total Tau and pS262 Tau levels in mouse hippocampus and cortex, and activated PP2A (Fig. 3).ConclusionSmall‐molecular PREP ligands, such as KYP‐2047 and HUP‐46 have disease‐modifying effects on cellular and animal models of tauopathies.

Synergistic Pulmonoprotective Effect of Natural Prolyl Oligopeptidase Inhibitors in In Vitro and In Vivo Models of Acute Respiratory Distress Syndrome.

Acute respiratory distress syndrome (ARDS) is a highly morbid inflammatory lung disease with limited pharmacological interventions. The present study aims to evaluate and compare the potential pulmonoprotective effects of natural prolyl oligopeptidase (POP) inhibitors namely rosmarinic acid (RA), chicoric acid (CA), epigallocatechin-3-gallate (EGCG) and gallic acid (GA), against lipopolysaccharide (LPS)-induced ARDS. Cell viability and expression of pro-inflammatory mediators were measured in RAW264.7 cells and in primary murine lung epithelial and bone marrow cells. Nitric oxide (NO) production was also assessed in unstimulated and LPS-stimulated RAW264.7 cells. For subsequent in vivo experiments, the two natural products (NPs) with the most favorable effects, RA and GA, were selected. Protein, cell content and lipid peroxidation levels in bronchoalveolar lavage fluid (BALF), as well as histopathological changes and respiratory parameters were evaluated in LPS-challenged mice. Expression of key mediators involved in ARDS pathophysiology was detected by Western blotting. RA and GA favorably reduced gene expression of pro-inflammatory mediators in vitro, while GA decreased NO production in macrophages. In LPS-challenged mice, RA and GA co-administration improved respiratory parameters, reduced cell and protein content and malondialdehyde (MDA) levels in BALF, decreased vascular cell adhesion molecule-1 (VCAM-1) and the inducible nitric oxide synthase (iNOS) protein expression, activated anti-apoptotic mechanisms and down-regulated POP in the lung. Conclusively, these synergistic pulmonoprotective effects of RA and GA co-administration could render them a promising prophylactic/therapeutic pharmacological intervention against ARDS.