Synthesis and evaluation of novel α-heteroaryl-phenylpropanoic acid derivatives as PPARα/γ dual agonists

The synthesis of a new series of phenylpropanoic acid derivatives incorporating an heteroaryl group at the α-position and their evaluation for binding and activation of PPARα and PPARγ are presented in this report. Among the new compounds, (S)-3-{4-[3-(5-methyl-2-phenyl-oxazol-4-yl)-propyl]-phenyl}-2-1,2,3-triazol-2-yl-propionic acid (17j), was identified as a potent human PPARα/γ dual agonist (EC₅₀ = 0.013 and 0.061 μM, respectively) with demonstrated oral bioavailability in rat and dog. 17j was shown to decrease insulin levels, plasma glucose, and triglycerides in the ZDF female rat model. In the human apolipoprotein A-1/CETP transgenic mouse model 17j produced increases in hApoA1 and HDL-C and decreases in plasma triglycerides. The increased potency for binding and activation of both PPAR subtypes observed with 17j when compared to previous analogs in this series was explained based on results derived from crystallographic and modeling studies.     

Design,synthesis and evaluation of novel zwitterionic compounds as PPARα/γ dual agonists (1)

We describe here the design, syntheses and structure–activity relationships (SAR) of novel zwitterionic compounds as non-thiazolidinedion (TZD) based peroxisome proliferator activated receptor (PPAR) α/γ dual agonists. We commenced the medicinal research with compound 1 originated by Eli Lilly, which was reported to possess PPAR α/γ dual agonist activity. We incorporated an amine linker and optimized it on the nitrogen of the linker, thereby envisioning the enhancement of the PPAR α/γ dual agonist activity together with altering the physicochemical properties. As a result, we could generate compounds showing the PPAR α/γ dual activity, especially among which compound 22e had a franylmethyl group on the linker and 2,6-dimethyl phenyl ring at the carboxylic acid head group furnishing a highly potent dual agonist activity, together with a great glucose lowering effect. Moreover, it remedied the lipid profile, that is, triglyceride without body weight gain in the db/db mice model.     

Synthesis and biological evaluation of bis-N2,N2′-(4-hydroxycoumarin-3-yl)ethylidene]-2,3-dihydroxysuccinodihydrazides

A series of N²,N²′-bis[4-hydroxycoumarin-3-yl)ethylidene]-2,3-dihydroxysuccino-hydrazides, containing 4-hydroxycoumarin, hydrazine and tartaric acid moieties, have been prepared and examined for possible biological activity. Several of these compounds exhibit promising HIV-1 integrase inhibition (IC₅₀ = 3.5 μM), and anti-T. brucei (32% viability) and anti-mycobacterial (Visual MIC90 = 15.63 μM) activity.     

Discovery of (3S,4S)-3-methyl-3-(4-fluorophenyl)-4-(4-(1,1,1,3,3,3-hexafluoro-2-hydroxyprop-2-yl)phenyl)pyrrolidines as novel RORγt inverse agonists

A novel series of cis-3,4-diphenylpyrrolidines were designed as RORγt inverse agonists based on the binding conformation of previously reported bicyclic sulfonamide 1. Preliminary synthesis and structure–activity relationship (SAR) study established (3S,4S)-3-methyl-3-(4-fluorophenyl)-4-(4-(1,1,1,3,3,3-hexafluoro-2-hydroxyprop-2-yl)phenyl)pyrrolidine as the most effective scaffold. Subsequent SAR optimization led to identification of a piperidinyl carboxamide 31, which was potent against RORγt (EC₅₀ of 61 nM in an inverse agonist assay), selective relative to RORα, RORβ, LXRα and LXRβ, and stable in human and mouse liver microsomes. Furthermore, compound 31 exhibited considerably lower PXR Y_max (46%) and emerged as a promising lead. The binding mode of the diphenylpyrrolidine series was established with an X-ray co-crystal structure of 10A/RORγt.     

Synthesis and biological evaluation of 1-substituted-3(5)-(6-methylpyridin-2-yl)-4-(quinolin-6-yl)pyrazoles as transforming growth factor-β type 1 receptor kinase inhibitors

A series of 1-substituted-3(5)-(6-methylpyridin-2-yl)-4-(quinolin-6-yl)pyrazoles 14a-e, 15a-e, 17a-c, and 18a-d have been synthesized and evaluated for their ALK5 inhibitory activity in an enzyme assay and in a cell-based luciferase reporter assay. The 6-quinolinyl pyrazole analogue 14b inhibited ALK5 phosphorylation with IC(50) value of 0.022 μM and showed 84% inhibition at 0.1 μM in a luciferase reporter assay using HaCaT cells permanently transfected with p3TP-luc reporter construct.     

Synthesis,molecular modeling and evaluation of novel N′-2-(4-benzylpiperidin-/piperazin-1-yl)acylhydrazone derivatives as dual inhibitors for cholinesterases and Aβ aggregation

To develop new drugs for treatment of Alzheimer’s disease, a group of N′-2-(4-Benzylpiperidin-/piperazin-1-yl)acylhydrazones was designed, synthesized and tested for their ability to inhibit acetylcholinesterase, butyrylcholinesterase and aggregation of amyloid beta peptides (1–40, 1–42 and 1–40_1–42). The enzyme inhibition assay results indicated that compounds moderately inhibit both acetylcholinesterase and butyrylcholinesterase. β-Amyloid aggregation results showed that all compounds exhibited remarkable Aβ fibril aggregation inhibition activity with a nearly similar potential as the reference compound rifampicin, which makes them promising anti-Alzheimer drug candidates. Docking experiments were carried out with the aim to understand the interactions of the most active compounds with the active site of the cholinesterase enzymes.     

Synthesis and biological evaluation of 4β-(thiazol-2-yl)amino-4′-O-demethyl-4-deoxypodophyllotoxins as topoisomerase-II inhibitors

A series of 4β-(thiazol-2-yl)amino-4′-O-demethyl-4-deoxypodophyllotoxins were synthesized, and their cytotoxicities were evaluated against four human cancer cell lines (A549, HepG2, HeLa, and LOVO cells) and normal human diploid fibroblast line WI-38. Some of the compounds exhibited promising antitumor activity and less toxicity than the anticancer drug etoposide. Among them, compounds 15 and 17 were found to be the most potent synthetic derivatives as topo-II inhibitors, and induced DNA double-strand breaks via the p73/ATM pathway as well as the H2AX phosphorylation in A549 cells. These compounds also arrested A549 cells cycle in G2/M phase by regulating cyclinB1/cdc2(p34). Taken together, these results show that a series of compounds are potential anticancer agents.     

Synthesis and biological evaluation of 4-(piperid-3-yl)amino substituted 6-pyridylquinazolines as potent PI3Kδ inhibitors

PI3Kδ is an intriguing target for developing anti-cancer agent. In this study, a new series of 4-(piperid-3-yl)amino substituted 6-pyridylquinazoline derivatives were synthesized. After biological evaluation, compounds A5 and A8 were identified as potent PI3Kδ inhibitors, with IC₅₀ values of 1.3 and 0.7 nM, respectively, which are equivalent to or better than idelalisib (IC₅₀ = 1.2 nM). Further PI3K isoforms selectivity evaluation showed that compound A5 afforded excellent PI3Kδ selectivity over PI3Kα, PI3Kβ and PI3Kγ. A8 exhibited superior PI3Kδ/γ selectivity over PI3Kα and PI3Kβ. Moreover, compounds A5 and A8 selectively exhibited anti-proliferation against SU-DHL-6 in vitro with IC₅₀ values of 0.16 and 0.12 μM. Western blot analysis indicated that A8 could attenuate the AKT^S473 phosphorylation. Molecular docking study suggested that A8 formed three key H-bonds action with PI3Kδ, which may account for its potent inhibition of PI3Kδ. These findings indicate that 4-(piperid-3-yl)amino substituted 6-pyridylquinazoline derivatives were potent PI3Kδ inhibitors with distinctive PI3K-isoforms and anti-proliferation profiles.     

Synthesis and biological evaluation of 4(5)-(6-methylpyridin-2-yl)imidazoles and -pyrazoles as transforming growth factor-β type 1 receptor kinase inhibitors

A series of 4(5)-(6-methylpyridin-2-yl)imidazoles 16–19 and -pyrazoles 22–29, 33, and 34 have been synthesized and evaluated for their ALK5 inhibitory activity in an enzyme assay and in cell-based luciferase reporter assays. The 6-quinolinyl imidazole analogs 16 and 18 inhibited ALK5 phosphorylation with IC₅₀ values of 0.026 and 0.034 μM, respectively. In a luciferase reporter assay using HaCaT cells transiently transfected with p3TP-luc reporter construct, 18 displayed 66% inhibition at 0.05 μM, while competitor compounds 2 and 3 showed 44% inhibition. The binding mode of 18 generated by flexible docking studies with ALK5:18 complex shows that it fits well into the active site cavity of ALK5 by forming broad and tight interactions.     

Synthesis and evaluation of benzofuran-2-yl(phenyl)methanone derivatives as ligands for β-amyloid plaques

A series of benzofuran-2-yl(phenyl)methanone derivatives were synthesized and evaluated as novel probes for β-amyloid plaques. These derivatives were produced by a Rap-Stoermer condensation reaction. Compounds with a N,N-dimethylamino group displayed high affinity for Aβ(1-42) aggregates with K(i) values in the nanomolar range. Autoradiography with brain sections of AD model mice (APP/PS1) revealed that a radioiodinated probe, [(125)I]10, labeled β-amyloid plaques selectively and displayed good brain uptake (3.53% ID/g) at 2 min. The results suggest that benzofuran-2-yl(phenyl)methanone derivatives should be investigated further as potential probes for detecting β-amyloid plaques in the AD brain.     

Discovery and characterization of potent and selective 4-oxo-4-(5-(5-phenyl-1,2,4-oxadiazol-3-yl)indolin-1-yl)butanoic acids as S1P₁ agonists

S1P(1) receptor driven lymphopenia has proven utility in the treatment of an array of autoimmune disease states. As a part of our efforts to develop potent and selective S1P(1) receptor agonists, we have identified a novel chemical series of 4-oxo-4-(5-(5-phenyl-1,2,4-oxadiazol-3-yl)indolin-1-yl)butanoic acid S1P(1) receptor agonists.     

Synthesis of phenyl 2-acetamido-2-deoxy-3-O-α-l-fucopyranosyl-β-d-glucopyranoside and related compounds

The reaction of phenyl 2-acetamido-2-deoxy-4,6- O-(p-methoxybenzylidene)-β-d-glucopyranoside with 2,3,4-tri-O-benzyl-α-l-fucopyranosyl bromide under halide ion-catalyzed conditions proceeded readily, to give phenyl 2-acetamido-2-deoxy-4,6-O-(p-methoxybenzylidene)-3-O-(2,3,4-tri-O-benzyl-α-l-fucopyranosyl)-β-d-glucopyranoside (8). Mild treatment of 8 with acid, followed by hydrogenolysis, provided the disaccharide phenyl 2-acetamido-2-deoxy-3-O-α-l-fucopyranosyl-β-d-glucopyranoside. Starting from 6-(trifluoroacetamido)hexyl 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-d-glucopyranoside, the synthesis of 6-(trifluoroacetamido)hexyl 2-acetamido-2-deoxy-3-O-β-l-fucopyranosyl-β-d-glucopyranoside has been accomplished by a similar reaction-sequence. On acetolysis, methyl 2-acetamido-2-deoxy-3-O-α-l-fucopyranosyl-α-d-glucopyranoside gave 2-methyl-[4,6-di-O-acetyl-1,2-dideoxy-3-O-(2,3,4-tri-O-acetyl-α-l-fucopyranosyl)-α-d-glucopyrano]-[2, 1-d]-2-oxazoline as the major product.     

Synthesis and evaluation of 11β-(4-substituted phenyl) estradiol analogs: transition from estrogen receptor agonists to antagonists

IntroductionAs part of our program to develop estrogen receptor (ER) targeted imaging and therapeutic agents we chose to evaluate 11β-substituted estradiol analogs as a representative scaffold. Previous synthetic studies provided an entry into this class of compounds and other work indicated that 11β-(substituted aryl) estradiol analogs were potent antagonists of the ER. Little information existed about the specific structural features involved in the transition from agonism to antagonism for the 11β-aryl estradiol analogs or their potential as scaffolds for drug conjugation.MethodsWe prepared and characterized a series of 11β-(4-Substituted phenyl) estradiol analogs using modifications of existing synthetic methods. The new compounds, as well as standard steroidal agonists and antagonists, were evaluated as competitive ligands for the ERβ-LBD. Functional assays used the induction of alkaline phosphatase in Ishikawa cells to determine potency of the compounds as ER agonists or antagonists.ResultsThe synthetic strategy successfully generated a series of compounds in which the 4-substituent was sequentially modified from hydroxyl to methoxy to azidoethoxy/N,N-dimethylaminoethoxy and eventually to a prototypical 1,4-naphthoquinone-containing moiety. The new compounds all retained high relative binding affinity (RBA) for the ERα-LBD, ranging from 13–83% that of estradiol. No subtype selectivity was observed. More importantly, the transition from agonist to antagonist activity occurs at the 4-methoxy stage where the compound is a mixed antagonist. More notably, antagonism appeared to be more dependent upon the size of the 11β-substituent than upon the nature of the terminal groupConclusionsWe have developed a synthetic strategy that provides facile access to potent 11β-(4-substituted phenyl) estradiol analogs. The resultant compounds retain high affinity for the ERα-LBD and, more importantly, demonstrate potent antagonist activity in cells. Large functionalities distal to the 11β-phenyl ring had little additional effect on either affinity or efficacy, suggesting the incorporation of diverse imaging or biologically active groups can be attached without significantly compromising the ER-binding capacity. Future studies are in progress to exploit the 11β-aryl estradiol analogs as potential drug delivery systems and imaging agents.     

Synthesis and biological evaluation of 2-substituted-4-(3′,4′,5′-trimethoxyphenyl)-5-aryl thiazoles as anticancer agents

Antitumor agents that bind to tubulin and disrupt microtubule dynamics have attracted considerable attention in the last few years. To extend our knowledge of the thiazole ring as a suitable mimic for the cis-olefin present in combretastatin A-4, we fixed the 3,4,5-trimethoxyphenyl at the C4-position of the thiazole core. We found that the substituents at the C2- and C5-positions had a profound effect on antiproliferative activity. Comparing compounds with the same substituents at the C5-position of the thiazole ring, the moiety at the C2-position influenced antiproliferative activities, with the order of potency being NHCH₃ > Me ? N(CH₃)₂. The N-methylamino substituent significantly improved antiproliferative activity on MCF-7 cells with respect to C2-amino counterparts. Increasing steric bulk at the C2-position from N-methylamino to N,N-dimethylamino caused a 1–2 log decrease in activity. The 2-N-methylamino thiazole derivatives 3b, 3d and 3e were the most active compounds as antiproliferative agents, with IC₅₀ values from low micromolar to single digit nanomolar, and, in addition, they are also active on multidrug-resistant cell lines over-expressing P-glycoprotein. Antiproliferative activity was probably caused by the compounds binding to the colchicines site of tubulin polymerization and disrupting microtubule dynamics. Moreover, the most active compound 3e induced apoptosis through the activation of caspase-2, -3 and -8, but 3e did not cause mitochondrial depolarization.     

Synthesis of 7-(tetrahydropyran-2-yl)- and 7-(4-acetoxytetrahydropyran-2-yl)-ε-rhodomycinone and 7-(tetrahydropyran-2-yl)-ε-pyrromycinone

The ¹³C.n.m.r spectra of water-soluble and -insoluble glucans synthesized by enzymes isolated from six strains of Streptococcus mutans are interpreted. The glucans are shown to be composed primarily of α(1→3)- and α-(1→6)-linked glucosyl residues, and the relative abundance of each linkage is estimated from peak areas. Treatment of water-insoluble glucans with dextranase is found to result in water-soluble and -insoluble products, the former enriched in α-(1→6)-linkages and the latter in α-(1→3)-linkages. The structural conclusions arrived at by ¹³C-n.m.r. spectroscopy are consistent with data from methylation analysis and ¹H-n.m.r. spectroscopy.     

Synthesis and biological evaluation of novel 4β-(1,3,4-oxadiazole-2-amino)-podophyllotoxin derivatives

A series of new 4β-(1,3,4-oxadiazole-2-amino)-podophyllotoxin derivatives were designed and synthesized. Their cytotoxicity in vitro against six tumor cell lines (DU-145, SGC-7901, A549, SH-SY5Y, HepG2 and HeLa) were evaluated by standard MTT assay. The pharmacological results showed that most of the newly synthesized podophyllotoxin derivatives displayed potent cytotoxicity against at least one of the tested tumor cells; and among the new derivatives, 11b was more potent than podophyllotoxin against HepG2 and Hela cell lines. Furthermore, 11b exhibited much better selectivity toward the normal cell lines L929 and Vero than etoposide, 5-Fu and podophyllotoxin. The possible antitumor mechanism of 11b is to inhibit the activity of DNA topoisomerase II, result in the S-phase arrest, and then cause apoptotic cell death.     

Synthesis and biological evaluation of 3-(azolylmethyl)-1H-indoles and 3-(α-azolylbenzyl)-1H-indoles as selective aromatase inhibitors

This present study identifies a number of azolyl-substituted indoles as potent inhibitors of aromatase. In the sub-series of 3-(azolylmethyl)-1H-indoles, four imidazole derivatives and their triazole analogues were tested. Imidazole derivatives 11 and 14 in which the benzyl moiety was substituted by 2-chloro and 4-cyano groups, respectively, were the most active, with IC₅₀ values ranging between 0.054 and 0.050 μM. In the other sub-series, eight 3-(α-azolylbenzyl)-1H-indoles were prepared and tested. Compound 30, the N-ethyl imidazole derivative, proved to be an aromatase inhibitor, showing an IC₅₀ value of 0.052 μM. All target compounds were further evaluated against 17α-hydroxylase/C17,20-lyase to determine their selectivity profile.     

Synthesis and biological evaluation of 1-(6-methylpyridin-2-yl)-5-(quinoxalin-6-yl)-1,2,3-triazoles as transforming growth factor-β type 1 receptor kinase inhibitors

A series of 1-(6-methylpyridin-2-yl)-5-(quinoxalin-6-yl)-1,2,3-triazoles has been synthesized and evaluated for their ALK5 inhibitory activity. The 1-(6-methylpyridin-2-yl)-1,2,3-triazoles were assembled by Cu(I)-catalyzed azide–alkyne 1,3-dipolar cycloaddition. Following this, quinoxaline was introduced through Pd-catalyzed direct arylation. The synthesized 1-(6-methylpyridin-2-yl)-5-(quinoxalin-6-yl)-1,2,3-triazoles revealed significant selectivity differences with respect to p38α MAP kinase. In particular, 12k showed 80.8% ALK5 inhibitory activity at a concentration of 10 μM and IC₅₀ value of 4.69 μM, but did not show p38α MAP kinase inhibitory activity (?1.94% inhibition at a concentration of 10 μM).