Exploration of 1-(3-chloro-4-(4-oxo-4H-chromen-2-yl)phenyl)-3-phenylurea derivatives as selective dual inhibitors of Raf1 and JNK1 kinases for anti-tumor treatment

Based on the roles of Raf1 and JNK1 in hepatocarcinoma development, scaffold-based drug design was employed to produce a series of compounds, which subsequently were synthesized and explored as potential dual inhibitors Raf1 and JNK1 kinases for anti-tumor treatment. The compound 1-(3-chloro-4-(6-ethyl-4-oxo-4H-chromen-2-yl)phenyl)-3-(4-chloro-phenyl)urea (3d) showed 66%, 67% and 13% inhibition rate at 50 μM against Raf1, JNK1 and p38-alpha, respectively, but no effect on ERK1 and ERK2, and inhibited the expression of pERK1/2 markedly and HepG2 cells proliferation with IC₅₀ at 8.3 μM. Furthermore, 3d showed lower toxicity against normal liver cell-lines QSG7701 and HL7702. Molecular docking study further showed that 3d can fit into binding domain of JNK1 and Raf1. Our data suggested the activities of 3d were associated with dual inhibition of JNK1 and Raf1 kinases.     

Hit-to-lead optimization and kinase selectivity of imidazo[1,2-a]quinoxalin-4-amine derived JNK1 inhibitors

As the result of a rhJNK1 HTS, the imidazo[1,2-a]quinoxaline 1 was identified as a 1.6 μM rhJNK1 inhibitor. Optimization of this compound lead to AX13587 (rhJNK1 IC₅₀ = 160 nM) which was co-crystallized with JNK1 to identify key molecular interactions. Kinase profiling against 125+ kinases revealed AX13587 was an inhibitor of JNK, MAST3, and MAST4 whereas its methylene homolog AX14373 (native JNK1 IC₅₀ = 47 nM) was a highly specific JNK inhibitor.     

Syntheses and biological evaluation of 1-heteroaryl-2-aryl-1H-benzimidazole derivatives as c-Jun N-terminal kinase inhibitors with neuroprotective effects

1-Heteroaryl-2-aryl-1H-benzimidazole derivatives were synthesized as inhibitors of c-Jun N-terminal kinases, JNK3. Their activities were evaluated through measurement of K_d using SPR, JNK3 kinase assay, and cell-viability of human neuroblastoma cells. Most tested compounds showed high affinity (10 μM–46 nM) to JNK3. Among them, compound 16f exhibited potent activities (K_d = 46 nM). Especially, 16f was also found to present a potent cell protective effect (IC₅₀ = 1.09 μM) against toxicity induced by anisomycin, showing a possibility as protective therapeutics in neuronal cell apoptosis.     

Fluorescence polarization-based assays for detecting compounds binding to inactive c-Jun N-terminal kinase 3 and p38α mitogen-activated protein kinase

Two fluorescein-labeled pyridinylimidazoles were synthesized and evaluated as probes for the binding affinity determination of potential kinase inhibitors to the c-Jun N-terminal kinase 3 (JNK3) and p38α mitogen-activated protein kinase (MAPK). Fluorescence polarization (FP)-based competition binding assays were developed for both enzymes using 1-(3′,6′-dihydroxy-3-oxo-3H-spiro[isobenzofuran-1,9′-xanthen]-5-yl)-3-(4-((4-(4-(4-fluorophenyl)-2-(methylthio)-1H-imidazol-5-yl)pyridin-2-yl)amino)phenyl)thiourea (5) as an FP probe (JNK3: K_d = 3.0 nM; p38α MAPK: K_d = 5.7 nM). The validation of the assays with known inhibitors of JNK3 and p38α MAPK revealed that both FP assays correlate very well with inhibition data received by the activity assays. This, in addition to the viability of both FP-based binding assays for the high-throughput screening procedure, makes the assays suitable as inexpensive prescreening protocols for JNK3 and p38α MAPK inhibitors.     

1-Aryl-3,4-dihydroisoquinoline inhibitors of JNK3

A series of 1-aryl-3,4-dihydroisoquinoline inhibitors of JNK3 are described. Compounds 20 and 24 are the most potent inhibitors (pIC50 7.3 and 6.9, respectively in a radiometric filter binding assay), with 10- and 1000-fold selectivity over JNK2 and JNK1, respectively, and selectivity within the wider mitogen-activated protein kinase (MAPK) family against p38α and ERK2. X-ray crystallography of 16 reveals a highly unusual binding mode where an H-bond acceptor interaction with the hinge region is made by a chloro substituent.     

Synthesis and SAR of novel isoxazoles as potent c-jun N-terminal kinase (JNK) inhibitors

The design and synthesis of isoxazole 3 is described, a potent JNK inhibitor with two fold selectivity over p38. Optimization of this scaffold led to compounds 27 and 28 which showed greatly improved selectivity over p38 by maintaining the JNK3 potency of compound 3. Extensive SAR studies will be described as well as preliminary in vivo data of the two lead compounds.     

Ultrafine particles from diesel engines induce vascular oxidative stress via JNK activation

Exposure to particulate air pollution is linked to increased incidences of cardiovascular diseases. Ambient ultrafine particles (UFP) from diesel vehicle engines have been shown to be proatherogenic in ApoE knockout mice and may constitute a major cardiovascular risk in humans. We posited that circulating nano-sized particles from traffic pollution sources induce vascular oxidative stress via JNK activation in endothelial cells. Diesel UFP were collected from a 1998 Kenworth truck. Intracellular superoxide assay revealed that these UFP dose-dependently induced superoxide (O₂^?) production in human aortic endothelial cells (HAEC). Flow cytometry showed that UFP increased MitoSOX red intensity specific for mitochondrial superoxide. Protein carbonyl content was increased by UFP as an indication of vascular oxidative stress. UFP also up-regulated heme oxygenase-1 (HO-1) and tissue factor (TF) mRNA expression, and pretreatment with the antioxidant N-acetylcysteine significantly decreased their expression. Furthermore, UFP transiently activated JNK in HAEC. Treatment with the JNK inhibitor SP600125 and silencing of both JNK1 and JNK2 with siRNA inhibited UFP-stimulated O₂^? production and mRNA expression of HO-1 and TF. Our findings suggest that JNK activation plays an important role in UFP-induced oxidative stress and stress response gene expression.     

Anti-atherosclerotic activities of flavonoids from the flowers of Helichrysum arenarium L. MOENCH through the pathway of anti-inflammation

We have successfully established AS model using thoracic aortas vascular ring which evaluated by the morphological changes of blood vessels, the proliferation of VSMC, and the expression of inflammation factors VEGF, CRP, JNK2 and p38. This AS model has the advantages of low cost, convenient and short period of established time. Moreover, we investigated the anti-AS activities of 7 flavonoids Narirutin (1), Naringin (2), Eriodictyol (3), Luteolin (4), Galuteolin (5), Astragalin (6), Kaempferol (7) from flowers of Helichrysum arenarium L. MOENCH by examining the vascular morphology, the inhibition on the expression of inflammation factors CRP, VEGF, JNK2, p38. In addition, we investigated the anti-AS activities of these 7 flavonoids by examining NO secretion of RAW264.7 cells in response to LPS. All above inflammation factors have been proved to be involved in the formation of AS. After comprehensive analysis of all results to discuss the structure–activity relationship, we summarized the conclusions at follow: compounds 1–7 could inhibit the expression of VEGF, CRP, JNK2, p38 and NO at different level, and we evaluated that flavonol aglycone have more significant anti-inflammation than it’s glycoside, and the anti-AS activity of flavonols were stronger than flavanones and flavones, which means that 3-group might be the effective group. Eventually, we supposed the main anti-inflammatory mechanism of these compounds was to reduce the expression of CRP, inhibit the kinases activity of JNK2 and p38, and then the MAPK pathway was suppressed, which resulted in the decrease of NO synthesis, VEGF expression and endothelial adhesion factor expression. And eventually, the scar tissue and vascular stenosis formations were prevented. This conclusion suggested flavonoids have the potential of preventing AS formation.     

Design and synthesis of a novel, orally active, brain penetrant, tri-substituted thiophene based JNK inhibitor

The SAR of a series of tri-substituted thiophene JNK3 inhibitors is described. By optimizing both the N-aryl acetamide region of the inhibitor and the 4-position of the thiophene we obtained single digit nanomolar compounds, such as 47, which demonstrated an in vivo effect on JNK activity when dosed orally in our kainic acid mouse model as measured by phospho-c-jun reduction.     

Highly selective c-Jun N-terminal kinase (JNK) 2 and 3 inhibitors with in vitro CNS-like pharmacokinetic properties prevent neurodegeneration

In this Letter, we describe the discovery of selective JNK2 and JNK3 inhibitors, such as 10, that routinely exhibit >10-fold selectivity over JNK1 and >1000-fold selectivity over related MAPKs, p38α and ERK2. Substitution of the naphthalene ring affords an isoform selective JNK3 inhibitor, 30, with approximately 10-fold selectivity over both JNK1 and JNK2. A naphthalene ring penetrates deep into the selectivity pocket accounting for the differentiation amongst the kinases. Interestingly, the gatekeeper Met146 sulfide interacts with the naphthalene ring in a sulfur-π stacking interaction. Compound 38 ameliorates neurotoxicity induced by amyloid-β in human cortical neurons. Lastly, we demonstrate how to install propitious in vitro CNS-like properties into these selective inhibitors.     

Protective effect of lanostane triterpenoids from the sclerotia of Poria cocos Wolf against cisplatin-induced apoptosis in LLC-PK1 cells

Cisplatin-induced nephrotoxicity is a serious adverse effect that limits the use of cisplatin in cancer patients. In the present study, we investigated the protective effect of lanostane triterpenoids (1–10) isolated from the ethanolic extract of Poria cocos Wolf against cisplatin-induced cell death in LLC-PK1 kidney tubular epithelial cells. Treatment of cisplatin induced significant cell death, which was suppressed by treatment with dehydroeburicoic acid monoacetate (1) and 3β-acetoxylanosta-7,9(11),24-trien-21-oic acid (9). Compound 1 exhibited the highest efficacy among the tested compounds and was thus subjected to further mechanistic studies. The increase in the percentage of apoptotic cells induced by cisplatin reduced by 4.3% after co-treatment of cells with compound 1 (50 and 100 μM). Furthermore, phosphorylation of the mitogen-activated protein kinases JNK, ERK, and p38, and caspase-3, which characterize oxidative stress-mediated apoptosis, increased significantly after treatment with cisplatin, and decreased after treatment with compound 1. These results indicate that the renoprotective effects of compound 1 may be mediated by its anti-apoptotic activity.     

Synthesis and SAR of piperazine amides as novel c-jun N-terminal kinase (JNK) inhibitors

A novel series of c-jun N-terminal kinase (JNK) inhibitors were designed and developed from a high-throughput-screening hit. Through the optimization of the piperazine amide 1, several potent compounds were discovered. The X-ray crystal structure of 4g showed a unique binding mode different from other well known JNK3 inhibitors.     

Highly selective c-Jun N-terminal kinase (JNK) 3 inhibitors with in vitro CNS-like pharmacokinetic properties II. Central core replacement

In this Letter, we describe the evolution of selective JNK3 inhibitors from 1, that routinely exhibit >10-fold selectivity over JNK1 and >1000-fold selectivity over related MAPKs. Strong SAR was found for substitution of the naphthalene ring, as well as for inhibitors adopting different central scaffolds. Significant potency gains were appreciated by inverting the polarity of the thione of the parent triazolothione 1, resulting in potent compounds with attractive pharmacokinetic profiles.     

Synthesis,antiproliferative and apoptosis induction potential activities of novel bis(indolyl)hydrazide-hydrazone derivatives

In recent years, indole-indazolyl hydrazide-hydrazone derivatives with strong cell growth inhibition and apoptosis induction characteristics are being strongly screened for their cancer chemo-preventive potential. In the present study, N-methyl and N,N-dimethyl bis(indolyl)hydrazide-hydrazone analog derivatives were designed, synthesized and allowed to evaluate for their anti-proliferative and apoptosis induction potential against cervical (HeLa), breast (MCF-7 and MDA-MB-231) and lung (A549) cancer cell lines relative to normal HEK293 cells. The MTT assay in conjunction with mitochondrial potential assays and the trypan blue dye exclusion were employed to ascertain the effects of the derivatives on the cancer cells. Further, mechanistic studies were conducted on compound 14a to understand the biochemical mechanisms and functional interactions with various signaling pathways triggered in HeLa and MCF-7 cells. Compound 14a induced apoptosis via caspase independent pathway through the participation of mitogen-activated protein kinases (MAPK) such as extracellular signal related kinase (ERK) and p38 as well as p53 pathways. It originates the activation of pro-apoptotic proteins such as Bak and Mcl-1s and also strongly induced the generation of reactive oxygen species. In downstream signaling pathway, activated p53 protein interacted with MAPK pathways, including SAPK/c-Jun N-terminal protein kinase (JNK), p38 and ERK kinases resulting in apoptotic cell death. The involvement of MAPK cascades such as p38, ERK and p38 on compound 14a induced apoptotic cell death was evidenced by the fact that the inclusion of specific inhibitors of p38, ERK1/2 and JNK MAPK (SB2035809, PD98059 and SP600125) prevented the compound 14a towards induced apoptosis. The results clearly showed that MAP kinase cascades were crucial for apoptotic response in compound 14a induced cellular killing and were dependent on p53 activity. Based on the results, compound 14a was identified as a promising candidate for cancer therapeutics and these findings furnish a basis for further in vivo experiments on anti-proliferative activity.     

Optimization and anti-inflammatory evaluation of methyl gallate derivatives as a myeloid differentiation protein 2 inhibitor

Myeloid differentiation protein 2 (MD2) is a co-receptor of toll-like receptor 4 (TLR4) responsible for the recognition of lipopolysaccharide (LPS) and mediates a series of TLR4-dependent inflammatory responses in inflammatory lung diseases including acute lung injury (ALI). Targeting MD2 thus may provide a therapeutic strategy against these lung diseases. In this study, we identified a novel compound 4k with the potent anti-inflammatory activity among 39 methyl gallate derivatives (MGDs). MGD 4k exhibited a high binding affinity to MD2, which in turn prevented the formation of the LPS/MD2/TLR4 complex. In addition, MGD 4k significantly reversed the upregulation of LPS-induced inflammatory mediators such as tumor necrosis factor-α, interleukin-6, intracellular adhesion molecule-1, vascular cell adhesion molecule-1, and monocyte chemoattractant protein-1 in vitro and in vivo. Mechanistically, MGD 4k performed anti-inflammatory function by inactivating JNK, ERK and p38 signaling pathways. Taken together, our study identified MGD 4k as a novel potential therapeutic agent for ALI through inhibiting MD2, inflammatory responses, and major inflammation-associated signaling pathways.     

Neurite Outgrowth of PC12 Cells by 4′-O-β-d-Glucopyranosyl-3′,4-Dimethoxychalcone from Brassica rapa L. ‘hidabeni’ was Enhanced by Pretreatment with p38MAPK Inhibitor

The cellular effects of eleven compounds including chalcone glycosides isolated from Brassica rapa L. ‘hidabeni’ and their synthetic derivatives were studied in rat pheochromocytoma PC12 cells. Of the compounds tested, 4′-O-β-d-glucopyranosyl-3′,4-dimethoxychalcone (A2) significantly increased the levels of the phosphorylated forms of extracellular signal-regulated kinases 1/2 (ERK 1/2), p38 mitogen-activated protein kinase (p38MAPK), and stress-activated protein kinases/Jun amino-terminal kinases (JNK/SAPK), but it did not affect Akt. Nerve growth factor (NGF), a well-known neurotrophic factor, increased the levels of phosphorylated ERK1/2, JNK/SAPK, and Akt but not p38MAPK, which may mediate marked neurite outgrowth. Signals evoked by A2 shared common characteristics with those induced by NGF; therefore, we evaluated the neuritogenic activity of A2 and found it induced only weak neurite outgrowth. However, this effect was enhanced by pre-treatment with a p38MAPK inhibitor, suggesting that the phosphorylation of p38MAPK down-regulated neurite outgrowth. From the results of this study, it was found that A2 in combination with a p38MAPK inhibitor can induce NGF-like effects. Hence, a combination of chalcone glycosides containing A2 and a p38MAPK inhibitor increases the likelihood that chalcone glycosides could be put to practical use in the form of drugs or alternative medicines to maintain neural health.     

JNK1 Protects against Glucolipotoxicity-Mediated Beta-Cell Apoptosis

Pancreatic β-cell dysfunction is central to type 2 diabetes pathogenesis. Prolonged elevated levels of circulating free-fatty acids and hyperglycemia, also termed glucolipotoxicity, mediate β-cell dysfunction and apoptosis associated with increased c-Jun N-terminal Kinase (JNK) activity. Endoplasmic reticulum (ER) and oxidative stress are elicited by palmitate and high glucose concentrations further potentiating JNK activity. Our aim was to determine the role of the JNK subtypes JNK1, JNK2 and JNK3 in palmitate and high glucose-induced β-cell apoptosis. We established insulin-producing INS1 cell lines stably expressing JNK subtype specific shRNAs to understand the differential roles of the individual JNK isoforms. JNK activity was increased after 3 h of palmitate and high glucose exposure associated with increased expression of ER and mitochondrial stress markers. JNK1 shRNA expressing INS1 cells showed increased apoptosis and cleaved caspase 9 and 3 compared to non-sense shRNA expressing control INS1 cells when exposed to palmitate and high glucose associated with increased CHOP expression, ROS formation and Puma mRNA expression. JNK2 shRNA expressing INS1 cells did not affect palmitate and high glucose induced apoptosis or ER stress markers, but increased Puma mRNA expression compared to non-sense shRNA expressing INS1 cells. Finally, JNK3 shRNA expressing INS1 cells did not induce apoptosis compared to non-sense shRNA expressing INS1 cells when exposed to palmitate and high glucose but showed increased caspase 9 and 3 cleavage associated with increased DP5 and Puma mRNA expression. These data suggest that JNK1 protects against palmitate and high glucose-induced β-cell apoptosis associated with reduced ER and mitochondrial stress.     

Novel autophagy modulators: Design and synthesis of (+)-epogymnolactam analogues and structure-activity relationship

(+)-Epogymnolactam (1) was discovered as a novel autophagy inducer from a culture of Gymnopus sp. in our laboratory. To determine structure-activity relationships among (+)-epogymnolactam analogues comparing with cerulenin (2), we synthesized 5 analogues including (?)-epogymnolactam (3) having each different functional group, and 3 analogues with different side-chain lengths. Five analogues, 3, 4, 5, 6, and 7 did not significantly increase the ratio of LC3-II to LC3-I as an autophagy marker in NIH3T3 cells. These results suggest that presence and stereochemistry of (2R,3S)-epoxy group and cyclic syn-form (1b) of 1 are important for the activity as autophagy inducer. Hexyl analogue (8) as well as 1 having butyl side-chain dose-dependently increased the ratio of LC3-II to LC3-I, whereas octyl analogue (9) and 2 rather decreased the ratio. Decyl analogue (10) did not give a change in the ratio. Although 8 seemed to be an excellent autophagy inducer, it dose-dependently increased SQSTM1 (p62) as in the case of 2, whereas 1 showed a slight dose-dependent decrease of p62 as an index of autophagic protein degradation. These observations suggest that 8 is an autophagy modulator with different molecular target from 1 or 2.     

Ulmosides A and B: Flavonoid 6-C-glycosides from Ulmus wallichiana,stimulating osteoblast differentiation assessed by alkaline phosphatase

Chemical investigation of Ulmus wallichiana stem bark resulted in isolation and identification of three new compounds (2S,3S)-(+)-3′,4′,5,7-tetrahydroxydihydroflavonol-6-C-β-d-glucopyranoside (1), (2S,3S)-(+)-4′,5,7-trihydroxydihydroflavonol-6-C-β-d-glucopyranoside (3) and 3-C-β-d-glucopyranoside-2,4,6-trihydroxymethylbenzoate (8), together with five known flavonoid-6-C-glucosides (2, 4–7). Their structures were elucidated using 1D and 2D NMR spectroscopic analysis. The absolute stereochemistry in compounds 1 and 3 were established with the help of CD data analysis and comparison with the literature data analysis. All the isolated compounds (1–8) were assessed for promoting the osteoblast differentiation using primary culture of rat osteoblast as an in vitro system. Compounds 1–3 and 5 significantly increased osteoblast differentiation as assessed by alkaline phosphatase activity.