Discovery of 2-phenyl-3-sulfonylphenyl-indole derivatives as a new class of selective COX-2 inhibitors

Design, synthesis, and antiproliferative activity of new indole/1,2,4-triazole/chalcone hybrids as EGFR and/or c-MET inhibitors

A novel group of indolyl-1,2,4-triazole-chalcone hybrids was designed, synthesized, and assessed for their anticancer activity. The synthesized compounds exhibited significant antiproliferative activity. Compounds 9a and 9e exhibited significant cancer inhibition with GI50 ranging from 3.69 to 20.40 µM and from 0.29 to >100 µM, respectively. Both compounds displayed a broad spectrum of anticancer activity with selectivity ratios ranging between 0.50-2.78 and 0.25-2.81 at the GI50 level, respectively. The synthesized compounds were also screened for their cytotoxicity by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazol (MTT) assay and for inhibition of epidermal growth factor receptor (EGFR) and c-MET (mesenchymal-epithelial transition factor). Some of the tested compounds exhibited significant inhibition against EGFR and/or c-MET. Compound 9b showed the highest c-MET inhibition (IC50 = 4.70 nM) compared to foretinib (IC50 = 2.5 nM). Compound 9d showed equipotent activity compared with erlotinib against EGFR (IC50 = 0.052 µM) and displayed significant c-MET inhibition with an IC50 value of 4.90 nM.

Indole-pyridine carbonitriles: multicomponent reaction synthesis and bio-evaluation as potential hits against diabetes mellitus

Background: Diabetes mellitus is a significant health disorder; therefore, researchers should focus on discovering new drug candidates. Methods: A series of indole-pyridine carbonitrile derivatives, 1-34, were synthesized through a one-pot multicomponent reaction and evaluated for antidiabetic and antioxidant potential. Results: In this library, 12 derivatives - 1, 2, 4, 5, 7, 8, 10-12, 14, 15 and 31 - exhibited potent inhibitory activities against α-glucosidase and α-amylase enzymes, in comparison to acarbose (IC50 = 14.50 ± 0.11 μM). Furthermore, kinetics, absorption, distribution, metabolism, excretion and toxicity and molecular docking studies were used to interpret the type of inhibition, binding energies and interactions of ligands with target enzymes. Conclusion: These results indicate that the compounds may be promising hits for controlling diabetes mellitus and its related complications.

Cu-Mediated Tandem 2,3-Disubstituted Indole Synthesis from Simple Anilines and Internal Alkynes via C-H Annulation

A simple, cost-effective, and straightforward method for the synthesis of 2,3-disubstituted indole scaffolds has been developed. The present protocol involves copper-mediated tandem hydroamination followed by C-H annulation of unprotected anilines with a wide range of internal alkynes. In the presence of Cu(OAc)₂·H₂O and trifluoroacetic acid (TFA), the reaction proceeds well to afford a variety of substituted indole derivatives in moderate to good yields. This process was found to be compatible with both primary and secondary anilines coupled with aromatic/aliphatic alkynes. High-purity copper nanoparticles can be recovered after the reaction, revealing the cost-effectiveness and environmentally benign feature of the current protocol.

Al-Humaidi J, Zaki MEA, Fathalla M, Gomha SM. Mechanochemical Synthesis and Molecular Docking Studies of New Azines Bearing Indole as Anticancer Agents

The development of new approaches for the synthesis of new bioactive heterocyclic derivatives is of the utmost importance for pharmaceutical industry. In this regard, the present study reports the green synthesis of new benzaldazine and ketazine derivatives via the condensation of various carbonyl compounds (aldehydes and ketones with the 3-(1-hydrazineylideneethyl)-1H-indole using the grinding method with one drop of acetic acid). Various spectroscopic techniques were used to identify the structures of the synthesized derivatives. Furthermore, the anticancer activities of the reported azine derivatives were evaluated against colon, hepatocellular, and breast carcinoma cell lines using the MTT technique with doxorubicin as a reference medication. The findings suggested that the synthesized derivatives exhibited potential anti-tumor activities toward different cell lines. For example, 3c, 3d, 3h, 9, and 13 exhibited interesting activity with an IC50 value of 4.27-8.15 µM towards the HCT-116 cell line as compared to doxorubicin (IC50 = 5.23 ± 0.29 µM). In addition, 3c, 3d, 3h, 9, 11, and 13 showed excellent cytotoxic activities (IC50 = 4.09-9.05 µM) towards the HePG-2 cell line compared to doxorubicin (IC50 = 4.50 ± 0.20 µM), and 3d, 3h, 9, and 13 demonstrated high potency (IC50 = 6.19-8.39 µM) towards the breast cell line (MCF-7) as compared to the reference drug (IC50 = 4.17 ± 0.20 µM). The molecular interactions between derivatives 3a-h, 7, 9, 11, 13, and the CDK-5 enzyme (PDB ID: 3IG7) were studied further using molecular docking indicating a high level of support for the experimental results. Furthermore, the drug-likeness analysis of the reported derivatives indicated that derivative 9 (binding affinity = -8.34 kcal/mol) would have a better pharmacokinetics, drug-likeness, and oral bioavailability as compared to doxorubicin (-7.04 kcal/mol). These results along with the structure-activity relationship (SAR) of the reported derivatives will pave the way for the design of additional azines bearing indole with potential anticancer activities.

Research progress on the structure and biological diversities of 2-phenylindole derivatives in recent 20 years

The privileged structure binds to multiple receptors with high affinity, which is helpful to the development of new bioactive compounds. Indole is classified as a privileged structure, which may be one of the most important structural categories in drug discovery. As a special subset of indole compounds, 2-phenylindole seems to be one of most promising forerunners of drug development. In this paper, 106 articles were referenced to review the structural changes, biological activities and structure-activity relationship of compounds in recent 20 years, and classified them according to their pharmacological activities, from several aspects, including anticancer, antibacterial, anti-inflammatory, analgesic, antiviral, anti-parasite, the biological activities target to central nervous system, et al. It also points out the importance of artificial intelligence (AI) technology in discovery of new 2-phenylindole compounds in a broader prospect. This review will provide some ideas for researchers to develop new indole drugs.

Recent progress in biologically active indole hybrids: a mini review

The indole moiety is one of the most widespread heterocycles found in both natural products and biological systems. Indoles have important biological activities including anticancer, antioxidant, anti-inflammatory, antifungal, anticholinesterase, and antibacterial properties. Scientists are therefore interested in the synthesis of biologically active indole-based hybrids such as indole-coumarin, indole-chalcone, indole-isatin, indole-pyrimidine and so on, with the aim of improving activity, selectivity, and mitigating side effects. This review will discuss the newly synthesized indole-based hybrids along with their biological activity which will be useful in drug discovery and development.

C3-Arylation of indoles with aryl ketones via C-C/C-H activations

C3-Arylation of indoles with aryl ketones is accomplished via palladium-catalyzed ligand-promoted Ar-C(O) cleavage and subsequent C-H arylation of indole. Various (hetero)aryl ketones are compatible in this reaction, affording the corresponding 3-arylindoles in moderate to good yields. Further introduction of an indole moiety into the natural products desoxyestrone and evodiamine demonstrate the synthetic utility of this protocol.

Sequential Sonogashira/intramolecular aminopalladation/cross-coupling of ortho-ethynyl-anilines catalyzed by a single palladium source: rapid access to 2,3-diarylindoles

We have developed a practical and efficient one-pot protocol for the synthesis of 2,3-diarylindoles via Pd-catalyzed bis-arylative cyclization of various o-ethynylanilines with aryl iodides. Mechanism studies showed that a Pd-catalyzed Sonogashira reaction took place firstly, giving an internal alkyne intermediate, which subsequently underwent intramolecular aminopalladation/cross-coupling to give access to 2,3-diarylindoles. The present methodology exhibits a broad substrate scope, producing various 2,3-diaryl indoles bearing two different aryl groups.

Direct C3-Selective Arylation of N-Unsubstituted Indoles with Aryl Chlorides, Triflates, and Nonaflates Using a Palladium-Dihydroxyterphenylphosphine Catalyst

A palladium-dihydroxyterphenylphosphine (DHTP) catalyst was successfully applied to the direct C3-arylation of N-unsubstituted indoles with aryl chlorides, triflates, and nonaflates. This catalyst showed C3-selectivity, whereas catalysts with other structurally related ligands exhibited N1-selectivity. Complex formation between the lithium salts of the ligand and the indole is assumed to accelerate the arylation at the C3 position. Reactions using 3-alkylindoles afforded 3,3-disubstituted indolenines, which can be further converted to the corresponding indoline derivatives.

Synthesis and Evaluation of Antimicrobial Activities of Novel N-Substituted Indole Derivatives

Indole motifs are one of the most significant scaffolds in the discovery of new drugs. We have described a synthesis of new N-substituted indole derivatives (1-3), and their in vitro antimicrobial activities were investigated. The synthesis of titled compounds has been demonstrated by utilizing commercially available starting materials. The antibacterial and antifungal activities were performed using new strains of bacteria Staphylococcus aureus, Escherichia coli, and Candida albicans using the disc diffusion method. Notably, the compound 4-(1-(2-(1H-indol-1-yl) ethoxy) pentyl)-N,N-dimethyl aniline (1) was found to be most potent than the other analogues (2 and 3), which has shown higher inhibition than the standard drug chloramphenicol.

Chemoselective metal-free indole arylation with cyclohexanones

Elemental sulfur- and iodine reagent-mediated indole C3 arylations have been developed with cyclohexanones as the arylating reagent.

Synthesis and anticancer activity of new [(Indolyl)pyrazolyl]-1,3,4-oxadiazole thioglycosides and acyclic nucleoside analogs

New [(Indolyl)pyrazolyl]-1,3,4-oxadiazole compounds and their derived thioglycosides as well as the corresponding sugar hydrazones were synthesized. The acyclo C-nucleoside analogs of the oxadiazoline base system were also prepared by reaction of acid hydrazides with aldehydo sugars followed by one pot process encompassing acetylation and cyclization of the synthesized hydrazones. The anticancer activity of the newly synthesized compounds was studied against colorectal carcinoma (HCT116), breast adenocarcinoma (MCF7) and prostate cancer (PC3) human tumor cell lines and a number of compounds showed moderate to high activities.

Development of Antioxidant COX-2 Inhibitors as Radioprotective Agents for Radiation Therapy-A Hypothesis-Driven Review

Radiation therapy (RT) evolved to be a primary treatment modality for cancer patients. Unfortunately, the cure or relief of symptoms is still accompanied by radiation-induced side effects with severe acute and late pathophysiological consequences. Inhibitors of cyclooxygenase-2 (COX-2) are potentially useful in this regard because radioprotection of normal tissue and/or radiosensitizing effects on tumor tissue have been described for several compounds of this structurally diverse class. This review aims to substantiate the hypothesis that antioxidant COX-2 inhibitors are promising radioprotectants because of intercepting radiation-induced oxidative stress and inflammation in normal tissue, especially the vascular system. For this, literature reporting on COX inhibitors exerting radioprotective and/or radiosensitizing action as well as on antioxidant COX inhibitors will be reviewed comprehensively with the aim to find cross-points of both and, by that, stimulate further research in the field of radioprotective agents.

A synthetic 2,3-diarylindole induces cell death via apoptosis and autophagy in A549 lung cancer cells

A series of 2,3-diarylindoles were synthesized via the Larock heteroannulation, and evaluated for their anticancer activity against A549 lung cancer cells. The most potent compound, PCNT13 with IC50=5.17 μM, caused the induction of two modes of programmed cell death, apoptosis and autophagy.

[3 + 2]-Annulations of N-alkyl-3-substituted indoles with quinone monoketals catalysed by Brønsted acids

An organocatalytic dearomative [3 + 2]-annulation of 3-alkylindoles and quinone monoketals provided benzofuro[2,3-b]indolines, while the reaction with 3-phenylindole leads to 2,3-diarylindoles in moderate yields.

Diaryl-Substituted (Dihydro)pyrrolo[3,2,1-hi]indoles, a Class of Potent COX-2 Inhibitors with Tricyclic Core Structure

A new compound class of diaryl-substituted heterocycles with tricyclic dihydropyrrolo[3,2,1-hi]indole and pyrrolo[3,2,1-hi]indole core structures has been designed and was synthesized by a modular sequence of Friedel-Crafts acylation, amide formation, and McMurry cyclization. This synthesis route represents a novel and versatile access toward dihydropyrrolo[3,2,1-hi]indoles and is characterized by good chemical yields and high modularity. From a set of 19 derivatives, 11 candidates were selected for determination of their COX inhibition potency and were found to be selective inhibitors with high affinity to COX-2 (IC50 ranging from 20-2500 nM and negligible inhibition of COX-1). The binding mode of the novel inhibitors in the active side of COX-2 was calculated in silico using the protein-ligand docking program GOLD by application of the molecular structures of two compounds derived from X-ray crystallography. Two novel compounds with high affinity to COX-2 (6k = 70 nM, 8e = 60 nM) have a fluoro substituent, making them promising candidates for the development of (18)F-radiolabeled COX-2 inhibitors for imaging purposes with positron emission tomography (PET).

2,3-Diaryl-substituted indole based COX-2 inhibitors as leads for imaging tracer development

A series of 2,3-diaryl-substituted indoles containing a fluorine or methoxy group was synthesized via Fischer indole synthesis, McMurry cyclization, or Bischler–Möhlau reaction to identify potential leads for PET radiotracer development.

Coreosides A-D, C14-polyacetylene glycosides from the capitula of Coreopsis tinctoria and its anti-inflammatory activity against COX-2

Four new C14-polyacetylene glycosides, namely coreosides A-D (1-4), were isolated from the capitula of Coreopsis tinctoria, a Snow chrysanthemum or Snow tea that is used as a folk tea for prevention of cardiovascular disease in southern Xinjiang, China. Coreosides A-D feature a long chain structure as its aglycon with two acetylenes on C-8 and C-10 and two olefinics on C-6 and C-12 sites, which construct a large conjugate system. The structures were elucidated on the basis of spectroscopic evidences and hydrolysis. Compounds 1-4 exhibited significant inhibition against cyclooxygenase-2 at the concentration of 1×10(-6) mol/L, with its IC50 values of 0.22-8.8×10(-2) μmol/L.

2-Carbaborane-3-phenyl-1H-indoles--synthesis via McMurry reaction and cyclooxygenase (COX) inhibition activity

Cyclooxygenase-2 (COX-2) inhibitors have been the focus of medicinal chemistry efforts for years, and many compounds that exhibit high selectivity and affinity have been developed. As carbaboranes represent interesting pharmacophores as phenyl mimetics in drug development, this paper presents the synthesis of carbaboranyl derivatives of COX-2-selective 2,3-disubstituted indoles. Despite the lability of carbaboranes under reducing conditions, 2-carbaborane-3-phenyl-1H-indoles could be synthesized by McMurry cyclization of the corresponding amides. Whereas the meta-carbaboranyl-substituted derivatives lacked COX inhibitory activity, an ortho-carbaboranyl analogue was active, but showed a selectivity shift toward COX-1.

Synthesis of 2-(N-Benzylpyrrolyl)-benzimidazoles Using Polyphosphoric Acid Prompted Cyclocondensation

Synthesis of a series of 2-substituted benzimidazoles was carried out for screening anti-inflammatory activities. 2-(N-benzylpyrrolyl)-benzimidazoles 9a-k were synthesized from N-benzyl-2-pyrrole carboxylic acids 8a-d and 4-substituted-1,2-phenylenediamines by cyclocondensation utilizing polyphosphoric acid (PPA) as condensing agent. The N-benzyl-2-pyrrole carboxylic acids were prepared by standard method of N-benzylation of 2-pyrrole carboxylate using NaH/DMF and appropriately substituted benzyl halides followed by alkaline hydrolysis.

Synthesis, biological evaluation, and docking studies of novel heterocyclic diaryl compounds as selective COX-2 inhibitors

Three novel series of diaryl heterocyclic derivatives bearing the 2-oxo-5H-furan, 2-oxo-3H-1,3-oxazole, and 1H-pyrazole moieties as the central heterocyclic ring were synthesized and their in vitro inhibitory activities on COX-1 and COX-2 isoforms were evaluated using a purified enzyme assay. The 2-oxo-5H-furan derivative 6b was identified as potent COX inhibitor with selectivity toward COX-1 (COX-1 IC(50)=0.061 microM and COX-2 IC(50)=0.325 microM; selectivity index (SI)=0.19). Among the 1H-pyrazole derivatives, 11b was found to be a potent COX-2 inhibitor, about 38 times more potent than Rofecoxib (COX-2 IC(50)=0.011 microM and 0.398 microM, respectively), but showed no selectivity for COX-2 isoform. Compound 11c demonstrated strong and selective COX-2 inhibitory activity (COX-1 IC(50)=1 microM, COX-2 IC(50)=0.011 microM; SI= approximately 92). Molecular docking studies of compounds 6b and 11b-d into the binding sites of COX-1 and COX-2 allowed to shed light on the binding mode of these novel COX inhibitors.

Fluorescent diarylindoles by palladium-catalyzed direct and decarboxylative arylations of carboxyindoles

Simple and brilliant: 1-Substituted 1H-indole-2-carboxylic acids efficiently undergo successive diarylation accompanied by C-H bond cleavage and decarboxylation upon treatment with aryl bromides in the presence of a palladium catalyst system to afford fluorescent 2,3-diarylindoles. This facile synthetic method provides a highly efficient blue emitter with a quantum yield of 0.97 in the solid state (see scheme).

Quantitative structure–activity relationship analysis of 2,3-diaryl indoles as selective cyclooxygenase-2 inhibitors

Quantitative structure-activity relationship (QSAR) studies have been performed on a combined series of 2-sulfonylphenyl-3-phenyl-indoles and 2-phenyl-3-sulfonylphenyl-indoles with a common 2,3 vicinal diaryl indole scaffold, recently reported as selective COX-2 inhibitors. This study is aimed to throw light on this, special class of diaryl heterocyclic family of selective COX-2 inhibitors. A preliminary Fujita-Ban analysis on 32 compounds provided valuable insights about the role of different substituents R1 and R2 around the 2,3 vicinal diaryl rings and R3, at position-5 of the central indole moiety in explaining their in vitro COX-2 inhibitory activity. The contribution of R1, R2, R3 towards COX-2 inhibitory activity resulted in statistically significant linear multiple regression equation with r = 0.942, r(2) = 0.888, s = 0.532 and F = 7.92, q(2) = 0.516 for 29 compounds. Fujita-Ban model shows a negative contribution of SO2NH2 and SO2CH3 at the R1 position; a negative contribution of 4-Cl, 2-Cl, 3-Cl, 3-CH3, 4-SO2CH3, 4-Br and a positive contribution of 4-OCH3, 4-CH3 substituents at the R2 position. At the R3 position a negative contribution of F, Br and a positive contribution of Cl, CH3 is encountered. In the light of our preliminary investigation that electron donating groups at the para position of R2 are conducive for COX-2 inhibitory activity from the Fujita-Ban model, we attempted to correlate the COX-2 inhibitory activity with quantum chemical descriptors of semi-empirical AM1 optimized geometries of the title compounds. Correlation analysis showed the molecular electronic descriptor, MOPAC total energy as crucial in governing COX-2 inhibitory activity of all the reported 41 compounds.