Discovery of new indole-based acylsulfonamide Nav1.7 inhibitors

Screening of 100 acylsulfonamides from the Bristol-Myers Squibb compound collection identified the C3-cyclohexyl indole 6 as a potent Na_v1.7 inhibitor. Replacement of the C2 furanyl ring of 6 with a heteroaryl moiety or truncation of this group led to the identification of 4 analogs with hNa_v1.7 IC₅₀ values under 50?nM. Fluorine substitution of the truncated compound 12 led to 34 with improved potency and isoform selectivity. The inverted indole 36 also maintained good activity. Both 34 and 36 exhibited favorable CYP inhibition profiles, good membrane permeability and a low efflux ratio and, therefore, represent new leads in the search for potent and selective Na_v1.7 inhibitors to treat pain.     

Synthesis and evaluation of inhibitors of cytochrome P450 3A (CYP3A) for pharmacokinetic enhancement of drugs

The HIV protease inhibitor ritonavir (RTV) is also a potent inhibitor of the metabolizing enzyme cytochrome P450 3A (CYP3A) and is clinically useful in HIV therapy in its ability to enhance human plasma levels of other HIV protease inhibitors (PIs). A novel series of CYP3A inhibitors was designed around the structural elements of RTV believed to be important to CYP3A inhibition, with general design features being the attachment of groups that mimic the P2–P3 segment of RTV to a soluble core. Several analogs were found to strongly enhance plasma levels of lopinavir (LPV), including 8, which compares favorably with RTV in the same model. Interestingly, an inverse correlation between in vitro inhibition of CYP3A and elevation of LPV was observed. The compounds described in this study may be useful for enhancing the pharmacokinetics of drugs that are metabolized by CYP3A.     

Triethylated chromones with substituted naphthalenes as tubulin inhibitors

Previously synthesized 2-(benzo[b]thiophene-3′-yl)-6,8,8-triethyldesmosdumotin B (1, TEDB-TB) and 2-(naphth-1′-yl)-6,8,8-triethyldesmosdumotin B (2) showed potent activity against multiple human tumor cell lines, including a multidrug-resistant (MDR) subline, by targeting spindle formation and/or the microtubule network. Consequently, ester analogues of hydroxylated naphthyl substituted TEBDs (3–5) were prepared and evaluated for their effects on tumor cell proliferation and on tubulin assembly. Among all new compounds, compound 6, a 4′-acetoxynaphthalen-1′-yl derivative, displayed the most potent antiproliferative activity (IC₅₀ 0.2–5.7 μM). Selected analogues were confirmed to be tubulin assembly inhibitors in cell-free and cell-based assays using MDR tumor cells. The new analogues partially inhibited colchicine binding to tubulin, suggesting their binding mode would be different from that of colchicine. This observation was supported by computational docking model analyses. Thus, the newly synthesized triethylated chromones with esterified naphthalene groups have good potential for development as a new class of mitotic inhibitors that target tubulin.     

Design,synthesis and biological evaluation of benzyloxyphenyl-methylaminophenol derivatives as STAT3 signaling pathway inhibitors

STAT3 signaling pathway has been validated as a vital therapeutic target for cancer therapy. Based on the novel STAT3 inhibitor of a benzyloxyphenyl-methylaminophenol scaffold hit (1) discovered through virtual screening, a series of analogues had been designed and synthesized for more potent inhibitors. The preliminary SAR had been discussed and the unique binding site in SH2 domain was predicted by molecular docking. Among them, compounds 4a and 4b exhibited superior activities than hit compound (1) against IL-6/STAT3 signaling pathway with IC₅₀ values as low as 7.71 μM and 1.38 μM, respectively. Compound 4a also displayed potent antiproliferative activity against MDA-MB-468 cell line with an IC₅₀ value of 9.61 μM. We believe that these benzyloxyphenyl-methylaminophenol derivatives represent a unique mechanism for interrogating STAT3 as well as a potential structure type for further exploration.     

The discovery of 2,5-isomers of triazole-pyrrolopyrimidine as selective Janus kinase 2 (JAK2) inhibitors versus JAK1 and JAK3

Members of the Janus kinase (JAK) family are potential therapeutic targets. Abnormal signaling by mutant JAK2 is related to hematological malignancy, such as myeloproliferative neoplasms (MPNs), and tyrosine kinase inhibitor (TKI)-resistance in non-small cell lung cancer (NSCLC). We discovered a potent and highly selective inhibitor of JAK2 over JAK1 and -3 based on the structure of 4-(2,5-triazole)-pyrrolopyrimidine. Among all triazole compounds tested, 2,5-triazole regioisomers more effectively inhibited JAK2 kinase activity than isomers with substitutions of various alkyl groups at the R₂ position, except for methyl-substituted 1,5-triazole, which was more potent than the corresponding 1,4- and 2,5-triazoles. None of the synthesized 1,4-isomers inhibited all three JAK family members. Compounds with phenyl or tolyl group substituents at the R₁ position were completely inactive compared with the corresponding analogues with a methyl substituted at the R₁ position. As a result of this structure–activity relationship, 54, which is substituted with a cyclopropylmethyl moiety, exhibited significant inhibitory activity and selectivity (IC₅₀ = 41.9 nM, fold selectivity JAK1/2 10.6 and JAK3/2 58.1). Compound 54 also exhibited an equivalent inhibition of wild type JAK2 and the V617F mutant. Moreover, 54 inhibited the proliferation of HEL 92.1.7 cells, which carry JAK2 V617F, and gefitinib-resistant HCC827 cells. Compound 54 also suppressed STAT3 phosphorylation at Y705.     

Discovery of thiazolidin-4-one urea analogues as novel multikinase inhibitors that potently inhibit FLT3 and VEGFR2

A series of novel thiazolidine-4-one urea analogues were designed, synthesized and biologically evaluated. The structure-activity relationship (SAR) at several positions of the scaffolds was investigated and its binding mode was analyzed by molecular modeling studies. Compound 17b proved to be the most potent one, and IC₅₀ values against A549 and HT-29 cancer cell lines were 0.65?μM and 0.11?μM, respectively. The results of kinase profile demonstrated that compound 17b is a multikinase inhibitor that potently inhibits FLT3 (IC₅₀?=?8.6?nM) and VEGFR2 (IC₅₀?=?18.7?nM). The results of real-time live-cell imaging indicated that compound 17b showed excellent cytotoxicity and anti-proliferative activity against HT-29 cancer cells in a time- and dose-dependent manner, which was significantly potent than that of Cabozantinib. In addition, in vitro antitumor activity was associated with inducing cancer cell apoptosis and suppression of cancer cell migration.     

The synthesis of 4-arylamido-2-arylaminoprimidines as potent EGFR T790M/L858R inhibitors for NSCLC

A series of 4-arylamido-2-arylaminoprimidines bearing acrylamide pharmacophore were synthesized as potent EGFR^T790M/L858R inhibitors among which 9c (IC₅₀?=?0.5872?nM), 9d (IC₅₀?=?2.213?nM), or 9h (IC₅₀?=?12.57?nM) showed more potent anti-EGFR^T790M/L858R activity compared with AZD–9291 (IC₅₀?=?20.80?nM) and possessed high SI displaying 307.6, 56.5, or 12.5 for EGFR^T790M/L858R over the wild-type respectively. 9h also showed pretty good activity against H 1975 cells with an IC₅₀ of 1.664?μM and exhibited low toxicity against the normal HBE cells (IC₅₀?>?20?μΜ). 9h had moderate selectivity for H 1975 over A 431 (SI?=?7.0) and the other selected cell lines. Morphological staining results further indicated that 9h could promote apoptosis. Hence, 9h was a promising compound for further investigation as a potential EGFR^T790M/L858R inhibitor for the treatment of NSCLC.     

Catalytic asymmetric synthesis of indole derivatives as novel α-glucosidase inhibitors in vitro

Indole containing compounds have acquired conspicuous significance due to their wide spectrum of biological activities. Synthesis of a series of enantiomerically pure indole derivatives 3a-r via Friedel–Crafts alkylation of indole 1 with enones 2a-r were described here. The products were isolated in a moderate to excellent yields (upto 89%) with excellent enantioselectivities (upto 99.9% ee). These compounds 3a-r were evaluated for their in vitro α-glucosidase inhibitory activity and some of them were identified as potent inhibitors (IC₅₀ = 4.3 ± 0.13–43.9 ± 0.51 μM) with several fold higher activity than the clinically used α-glucosidase inhibitor, acarbose (IC₅₀ = 840 ± 1.73 μM). To the best of knowledge, this is the first report of the propanone substituted indole ring containing compounds by in vitro α-glucosidase enzyme inhibition.     

N-1 and C-3 substituted indole Schiff bases as selective COX-2 inhibitors: synthesis and biological evaluation

A group of N-1 and C-3 disubstituted-indole Schiff bases bearing an indole N-1 (R′ = H, CH₂Ph, COPh) substituent in conjunction with a C-3 –CHN–C₆H₄–4-X (X = F, Me, CF₃, Cl) substituent were synthesized and evaluated as inhibitors of cyclooxygenase (COX) isozymes (COX-1/COX-2). Within this group of Schiff bases, compounds 15 (R¹ = CH₂Ph, X = F), 17 (R¹ = CH₂Ph, X = CF₃), 18 (R¹ = COPh, X = F) and 20 (R¹ = COPh, X = CF₃) were identified as effective and selective COX-2 inhibitors (COX-2 IC₅₀’s = 0.32–0.84 μM range; COX-2 selectivity index (SI) = 113 to >312 range). 1-Benzoyl-3-[(4-trifluoromethylphenylimino)methyl]indole (20) emerged as the most potent (COX-1 IC₅₀ >100 μM; COX-2 IC₅₀ = 0.32 μM) and selective (SI >312) COX-2 inhibitor. Furthermore, compound 20 is a selective COX-2 inhibitor in contrast to the reference drug indomethacin that is a potent and selective COX-1 inhibitor (COX-1 IC₅₀ = 0.13 μM; COX-2 IC₅₀ = 6.9 μM, COX-2 SI = 0.02). Molecular modeling studies employing compound 20 showed that the phenyl CF₃ substituent attached to the CN spacer is positioned near the secondary pocket of the COX-2 active site, the CN nitrogen atom is hydrogen bonded (N?NH = 2.85 Å) to the H90 residue, and the indole N-1 benzoyl is positioned in a hydrophobic pocket of the COX-2 active site near W387.     

(E)-3-(3,4,5-Trimethoxyphenyl)-1-(pyridin-4-yl)prop-2-en-1-one,a heterocyclic chalcone is a potent and selective CYP1A1 inhibitor and cancer chemopreventive agent

The overexpression of CYP1 family of enzymes is reported to be associated with development of human carcinomas. It has been well reported that CYP1A1 specific inhibitors prevents carcinogenesis. Herein, thirteen pyridine-4-yl series of chalcones were synthesized and screened for inhibition of CYP1 isoforms 1A1, 1B1 and 1A2 in Sacchrosomes? and live human HEK293 cells. The structure-activity relationship analysis indicated that chalcones bearing tri-alkoxy groups (8a and 8k) on non-heterocyclic ring displayed selective inhibition of CYP1A1 enzyme, with IC₅₀ values of 58 and 65?nM, respectively. The 3,4,5-trimethoxy substituted derivative 8a have shown >10-fold selectivity towards CYP1A1 with respect to other enzymes of the CYP1 sub-family and >100-fold selectivity with respect to CYP2 and CYP3 family of enzymes. The potent and selective CYP1A1 inhibitor 8a displayed antagonism of B[a]P mediated activation of aromatic hydrocarbon receptor (AhR) in yeast cells, and also protected human cells from CYP1A1-mediated B[a]P toxicity in human cells. This potent and selective inhibitor of CYP1A1 enzyme have a potential for development as cancer chemopreventive agent.     

Design,synthesis, and biological evaluation of resveratrol analogues as aromatase and quinone reductase 2 inhibitors for chemoprevention of cancer

A series of new resveratrol analogues were designed and synthesized and their inhibitory activities against aromatase were evaluated. The crystal structure of human aromatase (PDB 3eqm) was used to rationalize the mechanism of action of the aromatase inhibitor 32 (IC₅₀ 0.59 μM) through docking, molecular mechanics energy minimization, and computer graphics molecular modeling, and the information was utilized to design several very potent inhibitors, including compounds 82 (IC₅₀ 70 nM) and 84 (IC₅₀ 36 nM). The aromatase inhibitory activities of these compounds are much more potent than that for the lead compound resveratrol, which has an IC₅₀ of 80 μM. In addition to aromatase inhibitory activity, compounds 32 and 44 also displayed potent QR2 inhibitory activity (IC₅₀ 1.7 μM and 0.27 μM, respectively) and the high-resolution X-ray structures of QR2 in complex with these two compounds provide insight into their mechanism of QR2 inhibition. The aromatase and quinone reductase inhibitors resulting from these studies have potential value in the treatment and prevention of cancer.     

Discovery of 2,4-diamino-5-cyanopyrimidine derivatives as protein kinase C theta inhibitors with mitigated time-dependent drug-drug interactions

Protein kinase C theta (PKCθ) plays a critical role in T cell signaling and has therapeutic potential for T cell-mediated diseases such as transplant rejection and rheumatoid arthritis. PKCθ inhibitors have emerged as effective immunomodulative agents for the prevention of transplant rejection. We previously reported that the 2,4-diamino-5-cyanopyrimidine derivative 2 was a potent PKCθ inhibitor; however, it exhibited CYP3A4 time-dependent inhibition (TDI). Here, we report the structural modification of compound 2 into 34 focusing on mitigating CYP3A4 TDI. Compound 34 exhibited potent in vitro activity with mitigated CYP3A4 TDI and efficacy in vivo transplant model.     

Cycloartane-type triterpenes from Euphorbia fischeriana stimulate human CYP3A4 promoter activity

A chemical study of the roots of Euphorbia fischeriana resulted in the isolation of seven triterpenes (1–7), including two new compounds: (24R,S)-3β-24,31-epoxy-24-methylcycloartane (1) and (24R,S)-3β,31-dihydroxy-24-methoxy-24-methylcycloartane (2). Their structures were elucidated through extensive spectroscopic analyses. Cycloartanes 1–4 showed significant human CYP3A4 promoter activity through a series of luciferase reporter assays. Of these compounds, 3 and 4 activated the pregnane X receptor (PXR) and induced CYP3A4 mRNA expression in human primary hepatocytes. However, despite showing the most potent human CYP3A4 promoter activity via a PXR-independent pathway, 2 did not affect CYP3A4 mRNA expression in human primary hepatocytes. This difference is correlated to substitutions in C-24 and C-25 of the cycloartane structure.     

Design,synthesis and biological evaluation of 7-nitro-1H-indole-2-carboxylic acid derivatives as allosteric inhibitors of fructose-1,6-bisphosphatase

A series of novel indole derivatives was synthesized as inhibitors of fructose-1,6-bisphosphatase (FBPase). Extensive structure–activity relationships were conducted and led to a potent FBPase inhibitor 3.9 with an IC₅₀ of 0.99 μM. The binding mode of this series of indoles was predicted using CDOCKER algorithm. The results of this research will shed light on the further design and optimization of novel small molecules as FBPase inhibitors.     

1,7-Disubstituted oxyindoles are potent and selective EP3 receptor antagonists

A series of novel 1,7-disubstituted oxyindoles were shown to be potent and selective EP₃ receptor antagonists. Variation of substitution pattern at the C-3 position of indole enhanced in vitro metabolic stability of the resulting derivatives. Series 27a–c showed >1000-fold selectivity over a panel of prostanoid receptors including IP, FP, EP₁, EP₂ and EP₄. These agents also featured low CYP inhibition and good activity in the functional rat platelet aggregation assay.     

Aroylguanidine-based factor Xa inhibitors: The discovery of BMS-344577

We report the design and synthesis of a novel class of N,N′-disubstituted aroylguanidine-based lactam derivatives as potent and orally active FXa inhibitors. The structure–activity relationships (SAR) investigation led to the discovery of the nicotinoyl guanidine 22 as a potent FXa inhibitor (FXa IC₅₀ = 4 nM, EC_2×PT = 7 μM). However, the potent CYP3A4 inhibition activity (IC₅₀ = 0.3 μM) of 22 precluded its further development. Detailed analysis of the X-ray crystal structure of compound 22 bound to FXa indicated that the substituent at the 6-position of the nicotinoyl group of 22 would be solvent-exposed, suggesting that efforts to attenuate the unwanted CYP activity could focus at this position without affecting FXa potency significantly. Further SAR studies on the 6-substituted nicotinoyl guanidines resulted in the discovery of 6-(dimethylcarbamoyl) nicotinoyl guanidine 36 (BMS-344577, IC₅₀ = 9 nM, EC_2×PT = 2.5 μM), which was found to be a selective, orally efficacious FXa inhibitor with an excellent in vitro liability profile, favorable pharmacokinetics and pharmacodynamics in animal models.     

New class of alkynyl glycoside analogues as tyrosinase inhibitors

A new series of alkynyl glycoside analogues were designed and synthesized from cheap and a commercially available sugar by introduction of various alkynyl and alkyl groups at C-1 and C-6 positions of the sugar ring. The inhibitory abilities of alkynyl glycosides were investigated in vitro on mushroom tyrosinase for the catalysis of l-Tyrosine and l-DOPA as substrates and comparing with arbutin and kojic acid. Non-terminal alkyne compound 2d showed excellent tyrosinase inhibitory activity (IC₅₀ 54.0 μM) against l-Tyrosine comparable to arbutin (IC₅₀ 1.46 mM) while 2b exhibited potent activities (IC₅₀ 34.3 μM) against L-DOPA higher than kojic acid (IC₅₀ 0.11 mM) and arbutin (IC₅₀ 13.3 mM). Kinetic studies revealed that compound 2d was a non-competitive inhibitor with the best Ki value of 21 μM and formed an irreversible receptor complex with mushroom tyrosinase. The SARs results showed that the type of alkyne and alkyl groups at position C-6 on sugar and the stereoisomer played an important role in determining their inhibitory activities. The potent activity of alkynyl glycosides identified in this study highlight the importance of this scaffold and these compounds are very modestly potent to the development of new class for tyrosinase inhibitor.     

Synthesis and biological evaluation of a new series of berberine derivatives as dual inhibitors of acetylcholinesterase and butyrylcholinesterase

A series of novel berberine derivatives were designed, synthesized, and biologically evaluated as inhibitors of both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Among these derivatives, compound 48a, berberine linked with 3-methylpyridinium by a 2-carbon spacer, was found to be a potent inhibitor of AChE, with an IC₅₀ value of 0.048 μM and compound 40c, berberine linked with 2-thionaphthol by a 4-carbon spacer, acted as the most potent inhibitor for BuChE with an IC₅₀ value of 0.078 μM. Kinetic studies and molecular modeling simulations of the AChE-inhibitor complex indicated that a mixed-competitive binding mode existed for these berberine derivatives.