Substituted cinnamic anhydrides act as selective inhibitors of acetylcholinesterase

Cinnamic anhydrides have been shown to be more than reactive reagents, but they also act as inhibitors of the enzyme acetylcholinesterease (AChE). Thus, out of a set of 33 synthesised derivatives, several of them were mixed type inhibitors for AChE (from electric eel). Thus, (E)-3-(2,4-dimethoxyphenyl)acrylic anhydride (2c) showed K_i = 8.30 ± 0.94 µM and K_i′ = 9.54 ± 0.38 µM, and for (E)-3-(3-chlorophenyl)acrylic anhydride (2u) K_i = 8.23 ± 0.93 µM and K_i′ = 13.07 ± 0.46 µM were measured. While being not cytotoxic to many human cell lines, these compounds showed an unprecedented and noteworthy inhibitory effect for AChE but not for butyrylcholinesterase (BChE).     

Unexpected AChE inhibitory activity of (2E)α,β-unsaturated fatty acids

A small library of (E) α,β-unsaturated fatty acids was prepared, and 20 different saturated and mono-unsaturated fatty acids differing in chain length were subjected to Ellman’s assays to determine their ability to act as inhibitors for AChE or BChE. While the compounds were only very weak inhibitors of BChE, seven molecules were inhibitors of AChE holding IC₅₀?=?4.3–12.8?M with three of them as significant inhibitors of this enzyme. The results have shown trans 2-mono-unsaturated fatty acids are better inhibitors for AChE than their saturated analogs. Furthermore, the screening results indicate that the chain length is crucial for obtaining an inhibitory efficacy. The best results were obtained for (2E) eicosenoic acid (14) showing inhibition constants K_i?=?1.51?±?0.09?M and K_i′?=?7.15?±?0.55?M. All tested compounds were mixed-type inhibitors with a dominating competitive part. Molecular modelling calculations indicate a different binding mode of active/inactive compounds for the enzymes AChE and BChE.     

Evaluation of α-hydroxycinnamic acids as pyruvate carboxylase inhibitors

Through a structure-based drug design project (SBDD), potent small molecule inhibitors of pyruvate carboxylase (PC) have been discovered. A series of α-keto acids (7) and α-hydroxycinnamic acids (8) were prepared and evaluated for inhibition of PC in two assays. The two most potent inhibitors were 3,3′-(1,4-phenylene)bis[2-hydroxy-2-propenoic acid] (8u) and 2-hydroxy-3-(quinoline-2-yl)propenoic acid (8v) with IC₅₀ values of 3.0 ± 1.0 μM and 4.3 ± 1.5 μM respectively. Compound 8v is a competitive inhibitor with respect to pyruvate (K_i = 0.74 μM) and a mixed-type inhibitor with respect to ATP, indicating that it targets the unique carboxyltransferase (CT) domain of PC. Furthermore, compound 8v does not significantly inhibit human carbonic anhydrase II, matrix metalloproteinase-2, malate dehydrogenase or lactate dehydrogenase.     

Discovery,molecular dynamic simulation and biological evaluation of structurally diverse cholinesterase inhibitors with new scaffold through shape-based pharmacophore virtual screening

Designing small molecule inhibitors targeting cholinesterases (ChEs) is considered as an efficient strategy for the treatment of Alzheimer′s disease (AD). In the present study, based on a shaped-based pharmacophore (SBP) model that we reported previously, virtual screening was performed on four commercial compound databases, from which eight small molecules containing new structurally scaffolds were retained and evaluated. In general, six of these potential hits were identified to be selective ChEs inhibitors. Three compounds exhibited IC₅₀ values and K_i values in micromolar range on acetylcholinesterase (AChE), the most active compound 4 showed IC₅₀ value of 6.31 ± 2.68 μM and K_i value of 4.76 μM. Other three compounds displayed IC₅₀ values and K_i values in micromolar range on butyrylcholinesterase (BChE) with high target selectivity, the most active compound 1 showed IC₅₀ value of 3.87 ± 2.48 μM and K_i value of 1.52 μM. Multiple biological evaluations were performed to determine their cytotoxicity, cyto-protective effects, antioxidant effect as well as druglike properties. These compounds provide new cores for the further design and optimization, with the aim to discover new ChEs inhibitors for the treatment of AD.     

Syntheses of 1-[2-(Phosphonomethoxy)Alkyl]Thymine Monophosphates and an Evaluation of their Inhibitory Activity Toward Human Thymidine Phosphorylase

A series of new monophosphates of 1-[2-(phosphonomethoxy)alkyl]thymines, such as PMPTp_, 3-MeO-PMPTp, HPMPTp, and FPMPTp, were synthesized and tested for their ability to inhibit human thymidine phosphorylase. Kinetic measurements of enzyme activity were performed using thymidine and inorganic phosphate as the substrates. The data show that some monophosphates provide a considerable increase of the multisubstrate inhibitory effect. The highest inhibitory potency was found with (R)-FPMPTp 4c (K _i ^dT = 4.09 ± 0.47 μM, K _i(P_i) = 2.13 ± 0.29 μM) and (R) 3-MeO-PMPTp 4d (K _i ^dT = 5.78 ± 0.71 μM, K _i(P_i) = 2.71 ± 0.37 μM).     

Adenine nucleotide metabolism of blood platelets. VIII. Transport of adenine into human platelets

Adenine uptake into human blood platelets is a carrier-mediated process with a K_m of 159±21 nM and a V of 100±10 pmoles/min per 10⁹ platelets (in citrated platelet-rich plasma). The Q₁₀ was 2.53±0.22. A pH optimum was found at 7.5. Washing of the platelets increased the K_m to 453±33 nM and V to 397±38 pmoles/min per 10⁹ platelets. The change in shape induced in platelets by ADP was accompanied by an increase in V (2 times) and K_m (1.5 times).Guanine (K_i 50 μM), hypoxanthine (K_i 390 μM), adenine-N′-oxide (K_i 40 μM), adenosine (K_i 100 μM), RA 233 (K_i 75 μM) and papaverine (K_i 15 μM) acted as competitive inhibitors. Adenosine at low concentrations, and prostaglandin E₁ gave inhibition at only high adenine levels. A similar inhibition was obtained with 2-deoxy-d-glucose. Sulfhydryl-group inhibitors, pyrimidines and ouabain had no effect.     

Synthesis,biological evaluation,and docking studies of novel 5,6-diaryl-1,2,4-triazine thiazole derivatives as a new class of α-glucosidase inhibitors

A novel 5,6-diaryl-1,2,4-triazine thiazole derivatives (7a-7q) were synthesized and characterized by ¹H NMR and ¹³C NMR and evaluated for their α-glucosidase inhibitory activity. All tested compounds displayed good α-glucosidase inhibitory activity with IC₅₀ values ranging between 2.85 ± 0.13 and 14.19 ± 0.23 μM when compared to the standard drug acarbose (IC₅₀ = 817.38 ± 6.27 μM). Compound 7i (IC₅₀ = 2.85 ± 0.13 μM) exhibited the highest activity among this series of compounds. Molecular docking studies were carried out in order to investigate the binding mode of this class of compounds to α-glucosidase. This study showed that these 5,6-diaryl-1,2,4-triazine thiazole derivatives are a new class of α-glucosidase inhibitors.     

Design,synthesis, docking study, α-glucosidase inhibition,and cytotoxic activities of acridine linked to thioacetamides as novel agents in treatment of type 2 diabetes

A novel series of acridine linked to thioacetamides 9a–o were synthesized and evaluated for their α-glucosidase inhibitory and cytotoxic activities. All the synthesized compounds exhibited excellent α-glucosidase inhibitory activity in the range of IC₅₀ = 80.0 ± 2.0–383.1 ± 2.0 µM against yeast α-glucosidase, when compared to the standard drug acarbose (IC₅₀ = 750.0 ± 1.5 µM). Among the synthesized compounds, 2-((6-chloro-2-methoxyacridin-9-yl)thio)-N-(p-tolyl) acetamide 9b displayed the highest α-glucosidase inhibitory activity (IC₅₀ = 80.0 ± 2.0 μM). The in vitro cytotoxic assay of compounds 9a–o against MCF-7 cell line revealed that only the compounds 9d, 9c, and 9n exhibited cytotoxic activity. Cytotoxic compounds 9d, 9c, and 9n did not show cytotoxic activity against the normal human cell lines HDF. Kinetic study revealed that the most potent compound 9b is a competitive inhibitor with a K_i of 85 μM. Furthermore, the interaction modes of the most potent compounds 9b and 9f with α-glucosidase were evaluated through the molecular docking studies.     

Highly selective carbamate-based butyrylcholinesterase inhibitors derived from a naturally occurring pyranoisoflavone

This current study described the design and synthesis of a series of derivatives based on a natural pyranoisaflavone, which was obtained from the seeds of Millettia pachycarpa and displayed attractive BChE inhibition and high selectivity in our previous study. The inhibitory potential of all derivatives against two cholinesterases was evaluated. Only a few compounds demonstrated AChE inhibitory activity at the tested concentrations, while 26 compounds showed significant inhibition on BChE (the IC₅₀ values varied from 9.34 μM to 0.093 μM), most of them presented promising selectivity to ward BChE. Prediction of ADME properties for 7 most active compounds was performed. Among them, 9g (IC₅₀ = 222 nM) and 9h (IC₅₀ = 93 nM) were found to be the most potent BChE inhibitors with excellent selectivity over AChE (SI ratio = 1339 and 836, respectively). The kinetic analysis demonstrated both of them acted as mixed-type BChE inhibitors, while the molecular docking results indicated that they interacted with both residues in the catalytic active site. A cytotoxicity test on PC12 cells showed that both 9g and 9h had a therapeutic safety range similar to tacrine. Overall, the results indicate that 9h could be a good candidate of BChE inhibitors.     

New antibacterial and 5-lipoxygenase activities of synthetic benzyl phenyl ketones: Biological and docking studies

We investigated twelve benzyl phenyl ketone derivatives which are synthetic precursors of isoflavonoids that are shown be good 5-hLOX inhibitors, especially those that have the catechol group, but these precursors never have been assayed as 5-hLOX inhibitors being a novelty as inhibitors of the enzyme, due to sharing important structural characteristics. Screening assays, half maximal inhibitory concentration (IC₅₀) and kinetic assays of all the studied molecules (5 µg/ml in media assay) showed that 1-(2,4-dihydroxy-3-methylphenyl)-2-(3-chlorophenyl)-ethanone (K205; IC₅₀ = 3.5 µM; K_i = 4.8 µM) and 1-(2,4-dihydroxy-3-methylphenyl)-2-(2-nitrophenyl)-ethanone (K206; IC₅₀ = 2.3 µM; K_i = 0.7 µM) were potent, selective, competitive and nonredox inhibitors of 5-hLOX. Antioxidant behavior was also assayed by DPPH, FRAP, and assessing ROS production, and those with antibacterial and antiproliferative properties relating to 1-(2,4-dihydroxy-3-methylphenyl)-2-(2-chlorophenyl)-ethanone (K208) established it as the most interesting and relevant compound studied, as it showed nearly 100% inhibition of bacterial growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Finally, docking studies were done that helped to characterize how the inhibitor structures correlated to decreased 5-hLOX activity.     

Antiplasmodial activity of hydroxyethylamine analogs: Synthesis,biological activity and structure activity relationship of plasmepsin inhibitors

Malaria, particularly in endemic countries remains a threat to the human health and is the leading the cause of mortality in the tropical and sub-tropical areas. Herein, we explored new C₂ symmetric hydroxyethylamine analogs as the potential inhibitors of Plasmodium falciparum (P. falciparum; 3D7) in in-vitro cultures. All the listed compounds were also evaluated against crucial drug targets, plasmepsin II (Plm II) and IV (Plm IV), enzymes found in the digestive vacuole of the P. falciparum. Analog 10f showed inhibitory activities against both the enzymes Plm II and Plm IV (K_i, 1.93?±?0.29?µM for Plm II; K_i, 1.99?±?0.05?µM for Plm IV). Among all these analogs, compounds 10g selectively inhibited the activity of Plm IV (K_i, 0.84?±?0.08?µM). In the in vitro screening assay, the growth inhibition of P. falciparum by both the analogs (IC₅₀, 2.27?±?0.95?µM for 10f; IC₅₀, 3.11?±?0.65?µM for 10g) displayed marked killing effect. A significant growth inhibition of the P. falciparum was displayed by analog 12c with IC₅₀ value of 1.35?±?0.85?µM, however, it did not show inhibitory activity against either Plms. The hemolytic assay suggested that the active compounds selectively inhibit the growth of the parasite. Further, potent analogs (10f and 12c) were evaluated for their cytotoxicity towards mammalian HepG2 and vero cells. The selectivity index (SI) values were noticed greater than 10 for both the analogs that suggested their poor toxicity. The present study indicates these analogs as putative lead structures and could serve as crucial for the development of new drug molecules.     

Design,synthesis and bioevaluation of tricyclic fused ring system as dual binding site acetylcholinesterase inhibitors

Due to recently discovered non-classical acetylcholinesterase (AChE) function, dual binding-site AChE inhibitors have acquired a paramount attention of drug designing researchers. The unique structural arrangements of AChE peripheral anionic site (PAS) and catalytic site (CAS) joined by a narrow gorge, prompted us to design the inhibitors that can interact with dual binding sites of AChE. Eighteen homo- and heterodimers of desloratadine and carbazole (already available tricyclic building blocks) were synthesized and tested for their inhibition potential against electric eel acetylcholinesterase (eeAChE) and equine serum butyrylcholinesterase (eqBChE). We identified a six-carbon tether heterodimer of desloratadine and indanedione based tricyclic dihydropyrimidine (4c) as potent and selective inhibitor of eeAChE with IC₅₀ value of 0.09 ± 0.003 μM and 1.04 ± 0.08 μM (for eqBChE) with selectivity index of 11.1. Binding pose analysis of potent inhibitors suggest that tricyclic ring is well accommodated into the AChE active site through hydrophobic interactions with Trp84 and Trp279. The indanone ring of most active heterodimer 4b is stabilized into the bottom of the gorge and forms hydrogen bonding interactions with the important catalytic triad residue Ser200.     

Synthesis and antiproliferative activity of sulfonamide-based peptidomimetic calpain inhibitors

The calpains are a conserved family of cysteine proteases that includes several isoforms of which µ–calpain and m-calpain are the most widely distributed in mammalian cells. Calpains have been implicated in normal physiological processes as well as cellular abnormalities such as neurodegenerative disorders, cataract, and cancer. Therefore, calpain inhibitors are of interest as potential therapeutic agents. We have synthesized four new sulfonamide-based peptidomimetic compounds 2–5 as inhibitors of μ-calpain that incorporate (E)-1-(phenyl)-2-phenyldiazene and (E)-1-(phenyl)-2-phenylethene functionalities as the N-terminal capping groups of the inhibitors. Compound 5 with K_i value of 9 nM versus μ-calpain was the most potent member of the group. The compounds were predicted to be more lipophilic compared to MDL28170 based on CLogP estimation. They displayed moderate to good antiproliferative activity versus melanoma cell lines (A-375 and B-16F1) and PC-3 prostate cancer cells in vitro. Additionally, one member of the group (compound 3) inhibited DU-145 cell invasion by 80% at 2 μM concentration in the Matrigel cell invasion assay.     

Synthesis,neuroprotective and antioxidant capacity of PBN-related indanonitrones

In this work six PBN-related indanonitrones 1–6 have been designed, synthesized, and their neuroprotection capacity tested in vitro, under OGD conditions, in SH-SY5Y human neuroblastoma cell cultures. As a result, we have identified indanonitrones 1, 3 and 4 (EC₅₀ = 6.64 ± 0.28 μM) as the most neuroprotective agents, and in particular, among them, indanonitrone 4 was also the most potent and balanced nitrone, showing antioxidant activity in three experiments [LOX (100 μM), APPH (51%), DPPH (36.5%)], being clearly more potent antioxidant agent than nitrone PBN. Consequently, we have identified (Z)-5-hydroxy-N-methyl-2,3-dihydro-1H-inden-1-imine oxide (4) as a hit-molecule for further investigation.     

Competitive neutrophil elastase inhibitory isoflavones from the roots of Flemingia philippinensis

Flemingia philippinensis has been used throughout history to cure rheumatism associated with neutrophil elastase (NE). In this study, we isolated sixteen NE inhibitory flavonoids (1–16), including the most potent and abundant prenyl isoflavones (1–9), from the F. philippinensis plant. These prenyl isoflavones (2, 3, 5, 7, and 9) competitively inhibited NE, with IC₅₀ values of 1.3–12.0 μM. In addition, they were reversible, simple, slow-binding inhibitors according to their respective parameters. Representative compound 3 had an IC₅₀ = 1.3 μM, k₃ = 0.04172 μM⁻¹ min⁻¹, k₄ = 0.0064 min⁻¹, and K_i^app = 0.1534 μM. The K_ik/K_iv ratios (18.5 ∼ 24.6) for compound 3 were consistent with typical competitive inhibitors. The prenyl functionality of isoflavones significantly affected inhibitory potencies and mechanistic behavior by shifting the competitive mode to a noncompetitive one. The remaining flavonoids (10–16) were confirmed as mixed type I inhibitors that preferred to bind free enzyme rather than the enzyme-substrate complex. Fluorescence quenching analyses indicated that the inhibitory potency (IC₅₀) closely followed the binding affinity (K_SV).     

Novel anti-viability ceramide analogs: Design,synthesis, and structure–activity relationship studies of substituted (S)-2-(benzylideneamino)-3-hydroxy-N-tetradecylpropanamides

A group of novel l-serinamides, substituted (S)-2-(benzylideneamino)-3-hydroxy-N-tetradecylpropanamides (3a–o) and substituted (S)-2-(benzylamino)-3-hydroxy-N-tetradecyl propanamides (4c, 4i, 4l, and 4o), were synthesized as potential anti-tumor lead compounds. In vitro cell viability assay results indicate treatment with 3a–o compounds resulted in significant inhibition of cell viability in the chemoresistant breast cancer cell line, MCF-7TN-R. Compounds 3i and 3l, both ortho-substituted analogs, show the greatest efficacy with IC₅₀ values of 10.3 μM and 12.5 μM, respectively. The SAR analysis indicate that the imine functional group of 3a–o is critical for the cellular anti-viability effect, and the partial atomic charge (PAC) value of imine C atom is a valuable structural parameter for predicting the activity of these ceramide analogs.     

Leishmania mexicana: Conversion of dihydroorotate to orotate in amastigotes and promastigotes

The specific activity of dihydroorotate dehydrogenase, catalysing the conversion of l-5,6-dihydroorotate (l-DHO) to orotate, in Leishmania mexicana mexicana was found to be 22.1 ± 3.5 nmole/hr/mg protein in the amastigote, and 28.7 ± 4.6 nmole/hr/mg protein in the promastigote. The enzyme was found to be soluble and to require molecular O₂ for activity in both forms of the parasite. Oxygen utilisation was not mediated through the mitochondrial cytochrome-containing respiratory chain, and phenazine methosulphate and ferricyanide could be used as electron acceptors by the enzyme in both aerobic and anaerobic conditions. The enzyme from both amastigote and promastigote had a pH optimum of 7.0, and the K_m values for l-DHO were 11.8 ± 4.9 and 2.3 ± 0.4 μM, respectively. The pyrimidine analogs 5-methylorotate (K_i = 8.8 μM) and 5-aminoorotate (K_i = 57 μM) were shown to be competitive inhibitors of the promastigote enzyme, as was the reaction product orotate (K_i = 10 μM).     

Synthesis,and In Vitro and In Silico α-Glucosidase Inhibitory Studies of 5-Chloro-2-Aryl Benzo[d]thiazoles

Twenty-five derivatives of 5-chloro-2-aryl benzo[d]thiazole (1–25) were synthesized and evaluated for their α-glucosidase (S. cerevisiae EC 3.2.1.20) inhibitory activity in vitro. Among them eight compounds showed potent activity with IC₅₀ values between 22.1 ± 0.9 and 136.2 ± 5.7 μM, when compared with standard acarbose (IC₅₀ = 840 ± 1.73 μM). The most potent compounds 4, 9, and 10 showed IC₅₀ values in the range of 22.1 ± 0.9 to 25.6 ± 1.5 μM. Compounds 2, 5, 11, and 19 showed IC₅₀ values within the range of 40.2 ± 0.5 to 60.9 ± 2.0 μM. Compounds 1 and 3 were also found to be good inhibitors with IC₅₀ values 136.2 ± 5.7 and 104.8 ± 9.9 μM, respectively. Their activities were compared with α-glucosidase inhibitor drug acarbose (standard) (IC₅₀ = 840 ± 1.73 μM). The remaining compounds were inactive. Structure-activity relationships (SAR) have also been established. Kinetics studies indicated compounds 2, 3, 10, 19, and 25 to be non-competitive, while 1, 5, 9, and 11 as competitive inhibitors of α-glucosidase enzyme. All the active compounds (1–5, 9–11, and 19) were also found to be non-cytotoxic, in comparison to the standard drug i.e., doxorubicin (IC₅₀ = 0.80 ± 0.12 μM) in MTT assay. Furthermore, molecular interactions of active compounds with the enzyme binding sites were predicted through molecular modeling studies.     

Vinyl functionalized 5,6-dimethylbenzimidazolium salts: Synthesis and biological activities

A series of vinyl functionalized 5,6-dimethylbenzimidazolium salts are synthesized. All compounds were fully characterized by elemental analyses, MS, ¹H-NMR, ¹³C-NMR, and IR spectroscopy techniques. Enzyme inhibition is a very active area of research in drug design and development. In this study, the synthesized novel benzimidazolium salts were evaluated toward the human erythrocyte carbonic anhydrase I (hCA I), and II (hCA II) isoenzymes, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. They demonstrated highly potent inhibition ability against hCA I with K_i values of 484.8 ± 62.6–1389.7 ± 243.2 nM, hCA II with K_i values of 298.9 ± 55.7–926.1 ± 330.0 nM, α-glycosidase with K_i values of 170.3 ± 27–760.1 ± 269 μM, AChE with K_i values of 27.1 ± 3–77.6 ± 1.7 nM, and BChE with K_i values of 21.0 ± 5–61.3 ± 15 nM. As a result, novel vinyl functionalized 5,6-dimethylbenzimidazolium salts (1a–g) exhibited effective inhibition profiles toward studied metabolic enzymes. Therefore, we believe that these results may contribute to the development of new drugs particularly to treat some global disorders including glaucoma, Alzheimer's disease, and diabetes.     

Design,synthesis, anticancer evaluation,molecular docking and cell cycle analysis of 3-methyl-4,7-dihydropyrazolo[1,5-a]pyrimidine derivatives as potent histone lysine demethylases (KDM) inhibitors and apoptosis inducers

A novel series of pyrazolo[1,5-a]pyrimidines were synthesized and proved by their spectral and elemental analysis, some elected of the newly synthesized compounds were examined for their cytotoxic activity employing MTT assay on two cancer cell lines (Breast and Hela cancers). Compounds 5, 7e and 7i showed the higher cytotoxicity against two cancer cell lines with (IC₅₀ = 13.91 ± 1.4 and 22.37 ± 1.8 μM/L), (IC₅₀ = 6.56 ± 0.5 and 8.72 ± 0.9 μM/L) and (IC₅₀ = 4.17 ± 0.2 and 5.57 ± 0.4 μM/L) for two cancer cell lines breast and hela respectively, using doxorubicin as a reference drug. The most potent cytotoxic active compounds 5, 7e and 7i presented inhibitory activity against KDM (histone lysine demethylases) with IC₅₀ = 4.05, 1.91 and 2.31 μM, respectively. The most potent KDM inhibitor 7e (IC₅₀ = 1.91 μM) showed to cause cell cycle arrest at G2/M phase by 4 folds than control and induce total apoptotic effect by 10 folds more than control. In silico studies performed on the more potent cytotoxic active compounds 5, 7e and 7i included lipinisk's rule of five. Moreover, molecular docking study was utilized to explore the binding mode of the most active compounds to the target enzyme (PDB-ID: 5IVE). Also, some bioinformatics studies were carried out for compounds 7e and 7i using Swiss ADME (Swiss Institute of bioinformatics 2018).