Novel benzimidazole derivatives as phosphodiesterase 10A (PDE10A) inhibitors with improved metabolic stability

In this study, we report the identification of potent benzimidazoles as PDE10A inhibitors. We first identified imidazopyridine 1 as a high-throughput screening hit compound from an in-house library. Next, optimization of the imidazopyridine moiety to improve inhibitory activity gave imidazopyridinone 10b. Following further structure–activity relationship development by reducing lipophilicity and introducing substituents, we acquired 35, which exhibited both improved metabolic stability and reduced CYP3A4 time-dependent inhibition.     

Green chemistry appended synthesis,metabolic stability and pharmacokinetic assessment of medicinally important chromene dihydropyrimidinones

A green chemistry approach has been developed for the synthesis of chromene dihydropyrimidinone (CDHPM) using recyclable Fe/Al pillared clay catalyst. Pharmacokinetic parameters like aqueous solubility, lipophilicity, P-glycoprotein (P-gp) ATPase activity, permeability, plasma protein binding, red blood cell (RBC) partitioning, metabolic stability in liver microsomes and in silico computations have been studied for the most potent anticancer chromene dihydropyrimidinone hybrid 1. This compound exhibited low solubility, optimum lipophilicity, no P-gp inhibitory activity, intermediate permeability, high plasma protein binding, low RBC partitioning, acceptable metabolic stability in rat liver microsomes (RLM) as well as human liver microsomes (HLM) with transitional hepatic extraction ratio.     

Design,synthesis, and evaluation of carboxyl-modified oseltamivir derivatives with improved lipophilicity as neuraminidase inhibitors

In this study, a series of carboxyl-modified oseltamivir analogs with improved lipophilicity were designed and synthesized, and their inhibitory activities against neuraminidase from influenza A virus H5N1 subtype were evaluated. The results demonstrated that compound 5m exhibited potent inhibitory activity (IC₅₀?=?1.30?±?0.23?μM), and it targeted the recently discovered 430-cavity. Compound 5m (Log D?=??0.12) is more lipophilic than oseltamivir carboxylate (Log D?=??1.69) at pH 7.4, which is potentially propitious to improved membrane permeability and oral drug absorption. Meanwhile, 5m showed high stability in human liver microsomes. The findings of this study can be valuable in identifying neuraminidase inhibitors with optimal lipophilicity and in the exploration of 430-cavity.     

Lead generation and optimization of novel GPR119 agonists with a spirocyclic cyclohexane structure

We describe here the generation of a lead compound and its optimization studies that led to the identification of a novel GPR119 agonist. Based on a spirocyclic cyclohexane structure reported in our previous work, we identified compound 8 as a lead compound, being guided by ligand-lipophilicity efficiency (LLE), which linked potency and lipophilicity. Subsequent optimization studies of 8 for improvement of solubility afforded representative 21. Compound 21 had no inhibitory activity against six CYP isoforms and showed favorable pharmacokinetic properties and hypoglycemic activity in rats.     

Discovery, synthesis and biological evaluation of isoquinolones as novel and highly selective JNK inhibitors (2)

3-Metoxycarbonyl isoquinolone derivative 1 has been identified as a potent JNK inhibitor and significantly inhibited cardiac hypertrophy in a rat pressure-overload model. Herein, a series of isoquinolones with an imidazolylmethyl or a pyrazolylmethyl group at the 2-position were designed based on X-ray crystallographic analysis of the complex between the isoquinolone compound and JNK3, as wells as the relationship between compound lipophilicity (logD) and activity in a cell-based assay. The compounds prepared showed potent JNK1 inhibitory activities in a cell-based assay. Among them the isoquinolone derivative possessing 5-[(cyclopropylamino)carbonyl]-1-methyl-1H-pyrazole (16e) exhibited significant anti-hypertrophic activity at doses of more than 1mg/kg (po) in a pressure-overload model.     

Effect of a phenyl group in quaternary ammonium compounds on thiamine uptake in isolated rat hepatocytes

The inhibitory effect of a phenyl group in quaternary ammonium compounds on thiamine uptake in isolated rat hepatocytes was investigated. The phenyltrimethylammonium ion was a more potent inhibitor than the tetramethylammonium ion, while the dibenzyldimethylammonium ion was the most potent inhibitor of thiamine uptake among those compounds examined. A kinetic study showed that this compound was a competitive inhibitor. The cetyltrimethylammonium ion was a less effective inhibitor than the benzyltrimethylammonium ion, and the palmitoylcholine ion was a weak inhibitor. These results indicate that the lipophilicity of a quaternary ammonium compound is not always correlated with its affinity for thiamine-carrier binding, but the presence of a phenyl group plays a significant role in affinity. The inhibitory effect of the series of (CH₃)₃N⁺(CH₂)_nC₆H₅ (n = 0−6) compounds on thiamine uptake in isolated rat hepatocytes was studied. The maximal inhibitory activity occurred at n = 5. These results suggest that the phenyl group in a quaternary ammonium compound has a specific interaction with the thiamine-binding site in rat liver plasma membrane.     

Pharmacokinetic evaluation of medicinally important synthetic N,N′ diindolylmethane glucoside: Improved synthesis and metabolic stability

An improved route for the synthesis of N,N′-diindolyl methane (DIM) glycosides has been developed by using Fe/Al pillared clay catalyst. In-silico pharmacokinetics followed by in-vitro studies like aqueous solubility, lipophilicity, P-glycoprotein (P-gp) dependent ATPase activity, permeability, plasma protein binding, RBC partitioning, metabolic stability in different liver microsomes and its in-vitro-in-vivo extrapolation were conducted for the most potent derivative namely NGD16. The compound was found to have low solubility, optimum lipophilicity, no P-gp inhibitory activity, intermediate permeability, high plasma protein binding, low RBC partitioning, acceptable metabolic stability in rat liver microsomes (RLM) as well as human liver microsomes (HLM) with intermediate hepatic extraction ratio.     

Novel 3-O-acyl mesquitol analogues as free-radical scavengers and enzyme inhibitors: synthesis,biological evaluation and structure-activity relationship

A new isomer of mesquitol (2,3-trans-3',4',7,8-tetrahydroxyflavan-3-ol) was isolated from Dichrostachys cinerea in excellent yields. It has shown free-radical scavenging property and alpha-glucosidase inhibitory activities but, it could not display xanthine oxidase inhibitory property. However, it was observed that acylation of 3-OH group significantly enhanced the alpha-glucosidase inhibition and displayed xanthine oxidase inhibitory potential. The structure activity relationship revealed that the degree of lipophilicity played a major role in improving enzyme inhibitory activities. A positive correlation was observed between enzyme inhibitory potential and acyl chain length (upto C-16) of aliphatic esters.     

The discovery of YM-60828: a potent, selective and orally-bioavailable factor Xa inhibitor

Since Factor Xa (FXa) is well known to play a central role in thrombosis and hemostasis, inhibition of FXa is an attractive target for antithrombotic strategies. As a part of our investigation of a non-peptide, orally available FXa inhibitor, we found that a series of N-[(7-amidino-2-naphthyl)methyl]aniline derivatives possessed potent and selective inhibitory activities. Structure--activity relationship (SAR) of the substituent (R(1)) on the central aniline moiety suggested that increasing lipophilicity caused a detrimental effect on anticoagulant activity (prothrombin time assay) in plasma. Several compounds bearing a hydrophilic substituent in R(1) showed not only potent FXa inhibitory activities but also high anticoagulant activities. The best compound in this series was sulfamoylacetic acid derivative (YM-60828) which was a potent, selective and orally bioavailable FXa inhibitor and was chosen for clinical development.     

Glycogen phosphorylase inhibitory effects of 2-oxo-1,2-dihydropyridin-3-yl amide derivatives

Glycogen phosphorylase (GP) plays a crucial role in the conversion of glycogen to glucose-1-phosphate (and in turn glucose) and is a promising target for therapeutic intervention in diabetes. In this study we synthesized new derivatives of 2-oxo-1,2-dihydropyridin-3-yl amides using a facile aminolysis reaction, in which different alkyl and aryl esters and amides are substituted at N-1 and C-3 of the heterocyclic ring. The in vitro inhibitory activity of compounds against glycogen phosphorylase was evaluated. From this series the most potent compound exhibits good GPa inhibition (IC₅₀ = 6.3 μM). A preliminary study of these compounds showed that anti-GP activity was decreased by the incorporation of a C3–N carbonyl group and favored by increased lipophilicity.     

Design, synthesis, and anticancer activity of phosphonic acid diphosphate derivative of adenine-containing butenolide and its water-soluble derivatives of paclitaxel with high antitumor activity

Synthesis of adenine derivative of triphosphono-gamma-(Z)-ethylidene-2,3-dimethoxybutenolide 4 was accomplished by treatment of phosphonate 3 with 5-phosphoribosyl 1-pyrophosphate in the presence of 5-phosphoribosyl 1-pyrophosphate synthetase. It was found that triphosphonate 4 functions as an irreversible stoichiometric inactivator of the Escherichia coli ribonucleoside diphosphate reductase (RDPR). Triphosphonate 4 exhibited potent inhibitory activity against murine leukemias (L1210 and P388), breast carcinoma (MCF7), and human T-lymphoblasts (Molt4/C8 and CEM/0) cell lines. Paclitaxel ester derivatives of adenine-containing triphosphono-gamma-(Z)-ethylidene-2,3-dimethoxybutenolide 8-10 were also synthesized. Like triphosphonate 4, compound 8 exhibited inhibitory property toward RDPR. It also induced microtubule assembly similar to paclitaxel (5). The structure of the chlorodiester linker in 8 was found to account for this dual property. After treatment of MCF7 cells with compounds 4, 5, and 8, fluorescence microscope examination demonstrated the presence of nucleus shrinkage or segmentation. Bifunctional prodrug 8 exhibited higher lipophilicity than 4 and higher water-solubility than 5. Pro-dual-drug 8 exhibited more pronounced anticancer activity relative to that of the triphosphonate 4 and paclitaxel (5). In contrast, compound 9, resulting from the linkage of triphosphonate 4 and paclitaxel (5) through a diester unit, was only found to function as a highly water-soluble prodrug for paclitaxel (5). It induced microtubule assembly in vitro, but did not show inhibitory property toward RDPR. On the other hand, compound 10, an aggregate of triphosphonate 4 and paclitaxel (5), neither functioned as an inhibitor of RDPR nor exhibited microtubule assembly stimulating activity in vitro.     

Comparative Effects of Heterocyclic Compounds on Inhibition of Lettuce Fruit Germination

The molecules of many biologically active plant constituentscontain heterocyclic ring systems. Inhibitory effects of a numberof heterocyclic compounds and their alicyclic and open-chainanalogues on lettuce (Lactuca sativa L. cv. Great Lakes) germinationwere therefore determined under specified conditions. The mostobvious property which correlates chemical structure with biologicalactivity is lipophilicity, as was found in previous studies.However, other less obvious factors play a part. The inhibitoryactivity of coumarin, for instance, is much greater than wouldbe expected in comparison with compounds of related structures.In general, substitution of a carbon atom in a ring structureby oxygen or nitrogen has either little effect or a loweringeffect on activity, unless the increased solubility in waterallows an inhibitory concentration to be reached which did notoccur with the carbocyclic compound. However, introduction ofunsaturation increases activity markedly, especially with someof the indole compounds. Key words: Heterocyclic compounds, inhibitory compounds, lettuce germination     

Effects of substituted aryloxyaminopropanols on photosynthesis and photosynthesizing organisms

The inhibitory activity of 22 substituted aryloxyaminopropanols having beta-lytic and local anaesthetic properties was studied from the view-point of their influences on photosynthesis in plant chloroplasts as well as growth and synthesis of chlorophyll in algae and wheat plants. The inhibitory activity increased significantly with the increasing length of alkyl-substituents of the aryloxyaminopropanol molecule. Less pronounced dependences were found with respect to the position of the substituent chain on benzene ring. The inhibitory activity was found to correlate well with the lipophilicity of the compounds studied.     

Comparative Effects of Alicyclic Compounds and Quinones on Inhibition of Lettuce Fruit Germination

Germination of lettuce (Lactuca sativa L. cv. Great Lakes) fruitswas inhibited by many alicyclic compounds including monoterpenes.Quinones were particularly active. The hydrocarbons showed littleactivity correlated with their insolubility in water while compoundscontaining a keto group conjugated with a double bond showedhighest activity. As in previous studies the lipophilicity ofthe molecule was one of the main contributing factors to inhibition,provided that the value was not extreme, as for the hydrocarbons.In natural compounds noted for high inhibitory activity, severaldifferent substituents were present in the molecule and it seemslikely that each contributes different factors to the overalleffect. Some of these compounds are well known plant constituentsimplicated in allelopathy. Lettuce germination, Lactuca saliva, monoterpenes, quinones, abscisic acid, lipophilicity, inhibitory activity     

Platanetin: A Potent Natural Uncoupler and Inhibitor of the Exogenous NADH Dehydrogenase in Intact Plant Mitochondria

Platanetin is a 3,5,7,8-tetrahydroxy, 6-isoprenyl flavone isolated from the bud scales of the plane tree (Platanus acerifolia Willd.). Its effects on the oxidative activities of isolated potato and mung bean mitochondria have been studied. The most noticeable effect is the selective inhibitory effect of this compound on the activity of the external NADH dehydrogenase of the inner membrane. A 50% inhibition of the NADH oxidation rate is obtained at a 2 micromolar concentration. This activity is probably due to the flavonoid structure and the high lipophilicity of platanetin associated with the presence of the isoprenyl chain. Another important effect of platanetin is its uncoupling activity on oxidative phosphorylation. The presence of easily dissociable hydroxyl groups and the high lipophilicity of platanetin allow a potent H⁺ transfer through the mitochondrial inner membrane. This uncoupling activity is comparable to that of carbonyl cyanide p-trifluoromethoxyphenylhydrazone. Platanetin is therefore the most active natural uncoupler known at the present time (full uncoupling at 2 micromolar with succinate as substrate). At higher concentrations (10 micromolar and more), platanetin can transfer electrons from the mitochondrial inner membrane to O₂; the branching point of this KCN-salicylhydroxamic acid insensitive platanetin dependent oxidative pathway is located at the level of flavoproteins, no transfer occurring when succinate is the substrate. The redox properties of platanetin are in accord with such an activity.     

Design and synthesis of 6-fluoro-2-naphthyl derivatives as novel CCR3 antagonists with reduced CYP2D6 inhibition

In our previous study on discovering novel types of CCR3 antagonists, we found a fluoronaphthalene derivative (1) that exhibited potent CCR3 inhibitory activity with an IC(50) value of 20 nM. However, compound 1 also inhibited human cytochrome P450 2D6 (CYP2D6) with an IC(50) value of 400 nM. In order to reduce its CYP2D6 inhibitory activity, we performed further systematic structural modifications on 1. In particular, we focused on reducing the number of lipophilic moieties in the biphenyl part of 1, using ClogD(7.4) values as the reference index of lipophilicity. This research led to the identification of N-{(3-exo)-8-[(6-fluoro-2-naphthyl)methyl]-8-azabicyclo[3.2.1]oct-3-yl}-3-(piperidin-1-ylcarbonyl)isonicotinamide 1-oxide (30) which showed comparable CCR3 inhibitory activity (IC(50)=23 nM) with much reduced CYP2D6 inhibitory activity (IC(50)=29,000 nM) compared with 1.     

Synthesis and anti-HSV activity of tricyclic penciclovir and hydroxybutylguanine derivatives

A series of tricyclic penciclovir (PCV) and hydroxybutylguanine (HBG) derivatives have been prepared with enhanced lipophilicity following an efficient synthetic route. All the novel tricyclic derivatives were evaluated for inhibitory activity against herpes simplex virus 1 and 2 (HSV-1, HSV-2) and thymidine kinase deficient (ACV resistant) HSV-1. The tricyclic HBG derivatives were devoid of inhibitory activity however several of the tricyclic PCV derivatives showed promising antiviral activity, in particular 9g (R?=?4-MeO-C₆H₄) displayed good inhibitory activity (HSV-1 EC₅₀ 1.5?μM, HSV-2 EC₅₀ 0.8?μM) and retained inhibitory activity in HSV-1 TK^? cells (EC₅₀ 0.8?μM). Computational docking experiments supported the biological data observed and this preliminary study provides useful data for further development of tricyclic acyclic nucleoside derivatives with improved lipophilicity and retention of activity in HSV-1 TK deficient strains. Also, the new tricyclic derivatives were evaluated against a broad range of other DNA and RNA viruses, but were found to be inactive at subtoxic concentrations. In addition, weak to moderate cytostatic effect was observed for the new compounds.     

Lipophilicity and antiproliferative activity profiling of 2-benzylidencycloalkanones

High performance liquid chromatographic (HPLC) method has been developed to separate the members of a library including 24 benzylidenecycloalkanone-type structures and to characterize their lipophilicity. The experimental lipophilicity data (k) of the compounds have been compared with their calculated lipophilicity parameters (CLOGP). In general, good correlations between the measured and calculated lipophilicities have been found and these results were in good accordance with our previously data obtained in case of structurally related molecular libraries. In addition, cytotoxicity screening has been performed to determine the antiproliferative activity of these compounds. Some of the investigated compounds possessed noticeable inhibitory potential. Based on the correlation between the antiproliferative activity and experimentally determined lipophilicity of the molecules investigated, limited structural demands to obtain more potent compounds can be exhibited to support the synthetic design.