Indole Analogues Research Articles

“Synthesis and in-vitro Glucosidase Inhibitory Activity of Some Novel Indole Derivatives”

The objective of this paper is to focus on developing new entities of the heterocyclic molecule for its in-vitro inhibitory activities of glucosidase enzyme and the preparation and separation of new entities of the indole derivatives. Most of the indole derivatives are synthesized from the Phenyl Hydrazine and Ketone as a precursor. The prepared molecules were thoroughly tested for qualitative and quantitative analysis such as preliminary test, melting points, boiling points, Thin Layer Chromatography, Infra-Red spectroscopy, proton NMR spectroscopy, and element are determined by confirmation of final structure. The Indole ring compounds were analyzed and evaluated for glucosidase inhibitory activity by the In-vitro studies through the glucosidase inhibitory activity assay. Acarbose was used as a standard drug. The present data of in-vitro studies have led to the probable conclusion that the new Indole analogs would be taken as efficient glucosidase inhibitory activity.

MULTICOMPONENT ONE-POT SYNTHESIS OF NOVEL INDOLE ANALOGUES AS POTENT ANTIOXIDANT AGENTS

Objective: The purpose of this study was to design and synthesize innovative multicomponent one-pot indole analogues that would be effective antioxidants for the body. Methods: A novel series of indolyl-pyrimidine derivatives were synthesized and characterized by spectrum analysis, and their antioxidant activity and DPPH, total antioxidant capacity, ferric reducing antioxidant power methods, and DNA cleavage activity were examined. Results: Compound 6a displayed promising free radical scavenging and total antioxidant properties. Compound 6b has demonstrated excellent ferric reducing activity, which is due to the presence of a “CH3” substitution at five position of indole. When compared to a standard DNA marker, compound 6a demonstrated the highest DNA cleavage activity at desired concentrations. Conclusion: We have synthesized novel pyrimidine analogues containing an indole moiety to investigate drug-like molecules. We have devised that a method that is simple, multicomponent, has a short reaction time, and is ecologically benign.

Antihypertensive activity of indole and indazole analogues: A review

Heterocyclic compounds occupy an important position in chemistry because of their wide range of uses in drug design, photochemistry, agrochemicals, and other fields. Indole and indazole scaffolds are available from natural and synthetic sources, and molecules containing these scaffolds have been shown to have various biological effects, including anti-inflammatory, antibacterial, antiviral, antifungal, analgesic, anticancer, antioxidant, anticonvulsant, antidepressant, and antihypertensive activities. Indole and indazole molecules bind to receptors with high affinity, and thus are useful for the study of bioactive compounds involved in multiple pathways. In this review, we highlight the antihypertensive activity and the mechanisms of action of indole and indazole derivatives. In addition, structure–activity relationship studies of the antihypertensive effect are presented.

Synthesis and anticancer screening of some novel Pd-catalysed 3-methyl indole based analogues on Mia PaCa-2 cell line

Indole is a most prerogative moiety in the evaluation of anticancer agents for its versatility and bio-diversity. The indole based compounds have been reported by the researchers in the last decade with potent anticancer activities. The coupled indole ring system with other biodynamic moieties is known to increase the bio-efficiency. Hence, a series of 3-methyl-indole-2-pyrindine coupled secondary amines have been synthesized via Suzuki-Miyaura and Buchwald Hartwig coupling. The compounds 9a-e have been docked against Hypoxia-inducible factor 1α (HIF-1α) enzyme to demonstrate the binding interactions with the active site, shown the binding affinity from -7.5 to -8.1 Kcal/mol and disclosed the potentiality of synthesized compounds to bind and inhibits the HIF-1α (Pdb Id: 3KCX) pathway and predicted several in silico ADMET descriptors for the 3-methyl Indole analogues. The molecules were screened for their anti-pancreatic cancer activity and tested against Mia PaCa-2 cell line by MTT assay, revealed that; compound 9d exhibited a greater antiproliferation activity in the series, with IC50 of 73.63±2.05 µM. Our present findings revealed that 9d might be a pursuable lead for further anti-pancreatic cancer studies.

Role of indole curcumin in the epigenetic activation of apoptosis and cell cycle regulating genes.

Head-and-neck squamous cell carcinoma is associated with the epigenetic silencing of various genes such as DAPK, ataxia telangiectasia mutated (ATM), BRCA1, p16INK4a, pVHL, p16, and RASSF1A. The most common epigenetic change observed in these genes is DNA methylation that directs the studies toward finding inhibitors for DNA methyltransferases (DNMTs), the protagonist in the action. The present study focuses on analyzing the possibility whether indole curcumin can reverse epigenetic changes of the various tumor suppressor genes, characteristically silenced by methylation, by inhibiting the major methylation enzyme DNA methyltransferase 1 or DNMT1. The cytotoxic effects of indole curcumin were studied through the MTT and lactate dehydrogenase assays. To determine the apoptosis-mediated death of HEp-2 cells, fluorescence imaging using different stains was done. Gene or mRNA expression analysis was done for p53, ATM, and DAPK genes. The results obtained from this study clearly indicate that the indole analog of curcumin plays a remarkable role in activating genes involved in cell cycle regulation and apoptosis induction through epigenetic regulation. The influence that the drug has on the methylation status of gene promoter sequence of the ATM gene is also very significant. Indole curcumin, being an analog of curcumin, promises to be a very useful drug molecule having various potential targets. The target selected for this study was DNMT1 enzyme and the drug seems to actually show the effects; it was predicted to be having on the target molecule.

Synthesis, analgesic, anti-inflammatory, COX/5-LOX inhibition, ulcerogenic evaluation, and docking study of benzimidazole bearing indole and benzophenone analogs

Inflammation therapy is particularly focused on the development of safer non-steroidal anti-inflammatory drugs (NSAIDs), administered to control inflammation. It is typically considered that dual-inhibition of COX/5-LOX, which improves efficacy and has fewer side effects, is an effective technique for combating inflammation. In this perspective, the series of titled compounds (10a-j) were designed, synthesized, and characterized following with the anti-inflammatory, analgesic, and ulcerogenic evaluation. The investigation of the potentiality of the titled compounds (10a-j) displayed a high degree of anti-inflammatory activity. The compounds displaying potential analgesic activity were identified and validated further for evaluation of analgesic, anti-inflammatory activity, and subsequent ulcerogenic evaluation. In addition, the COX-1, COX-2, and 5-LOX analyses were carried out in vitro. Among (10a-j) series, compound 10c with para substitution of fluoro group on the benzoyl ring and two chloro groups at ortho position in phenyl ring of benzophenone was observed to have good inhibitory potency. Furthermore, the in silico docking study was performed by using AutoDock tools docking software.

Synthesis and antifungal activity of novel chiral indole analogues

Starting from L-tryptophan, 19 new N-substituted chiral indole analogs were synthesized. The prepared compounds were evaluated for biological activity against Sclerotinia sclerotiorum, Alternaria solani, Verticillium dahliae, Colletotrichum orbiculare, Cytospora juglandis and Curvularia lunata. The preliminary bioassays showed that most of the synthesized compounds exhibited fungicidal activity. Compound b13 in particular exhibited significant antifungal activity against Verticillium dahliae and Sclerotinia sclerotiorum, with the MIC value of 1.95 µg mL−1. Compound b13 also showed excellent activity against six plant pathogen fungi, and was identified as the most active on the biological assays, and will be studied further.

Semi-synthesis and cytotoxicity evaluation of pyrimidine, thiazole, and indole analogues of argentatins A–C from guayule (Parthenium argentatum) resin

Argentatins A–C (1–3), the major cycloartane-type triterpenoids of guayule resin, a byproduct of commercial rubber production, were converted into their pyrimidine (7–12), thiazole (13–15), and indole (16–18) analogues by a molecular hybridization approach. The cytotoxic activities of these fused heterocyclic analogues 7–18 were compared with those of argentatins A–C (1–3) against a panel of three sentinel human cancer cell lines [NCI-H460 (non-small cell lung), MCF-7 (breast adenocarcinoma), and SF-268 (central nervous system glioma)], and normal human fibroblast (WI-38) cells. The cytotoxicity data suggest that the pyrimidine analogues 7 and 8 (derived from 1), 9 and 10 (derived from 2), and 12 (derived from 3) had significantly enhanced activity compared to the parent compounds or their thiazole (13–15) and indole (16–18) analogues. These findings indicate that triterpenoid constituents of guayule resin may be exploited to obtain value-added products with potential applications in anticancer drug discovery.

Discovery of Novel Indole Derivatives as Fructose-1,6-bisphosphatase Inhibitors and X-ray Cocrystal Structures Analysis.

Liver fructose-1,6-bisphosphatase (FBPase) is a key enzyme in the gluconeogenesis, and its inhibitors are expected to be novel antidiabetic agents. Herein, a series of new indole and benzofuran analogues were designed and synthesized to evaluate the inhibitory activity against FBPase. As a result, the novel FBPase inhibitors bearing N-acylsulfonamide moiety on the 3-position of the indole-2-carboxylic acid scaffold (compounds 22f and 22g) were identified with IC50s at the submicromolar levels. Three X-ray crystal structures of the complexes were solved and revealed the structural basis for the inhibitory activity. The chemoinformatics analysis further disclosed the distinct binding features of this class of inhibitors, providing an insight for further modifications to create structurally distinct FBPase inhibitors with high potency and drug-like properties.

Construction of Hydrodibenzo[b,d]furan Frameworks from Morita-Baylis-Hillman Carbonates of Isatins and o-Hydroxy Enones via Palladium and Brønsted Base Relay Catalysis.

A cascade assembly between isatin-derived Morita-Baylis-Hillman carbonates and o-hydroxybenzylideneacetones has been developed under the relay catalysis of Pd(PPh3)4 and DBU, affording a spectrum of 1,2,3,4-tetrahydrodibenzo[b,d]furan architectures incorporating a spirooxindole motif in moderate to good yields with excellent diastereoselectivity. The fused indole analogues were similarly furnished by employing the benzylideneacetones having an o-TsNH group.

2-methylindole analogs as cholinesterases and glutathione S-transferase inhibitors: Synthesis, biological evaluation, molecular docking, and pharmacokinetic studies

• 2-methylindole analogs were designed, synthesized and characterized. • The target 2-methylindole analogs ( 4a–4j ) were evaluated for their inhibitory potential against glutathione S-transferase (GST), acetylcholinesterase (AChE), butyrylcholinesterase (BChE) inhibitory activities. • Molecular docking studies were conducted to correlate the in vitro results and to identify possible mode of interactions at the active pocket site of the receptors. • The pharmacokinetic studies of 2-methylindole analogs were carried out using SwissADMET analyses. In this study, we aimed to (i) synthesize new 2-methylindole analogs containing various amino structures, pyrrolidine, piperidine, morpholine, and substituted phenyl groups through structural and molecular modifications, (ii) evaluate the pharmaceutical potential of 2-methylindole analogs via assessing enzyme inhibitory activity against glutathione S-transferase (GST), acetylcholinesterase (AChE), and butyrylcholinesterase (BChE), (iii) predict ADMET and pharmacokinetic properties of the synthesized 2-methylindole analogs, (iv) reveal the possible interactions between the synthesized 2-methylindole analogs with GST, AChE, and BChE enzymes using several molecular docking software. In vitro enzyme inhibition assays showed that the synthesized indole analogs exhibited moderate to good inhibitory activities against GST, AChE, and BChE enzymes. Briefly, the inhibitory activities of the analogs 4b and 4i against AChE, 4a and 4b against BChE, and analogs 1 and 4i against GST were detected to be higher or close to the standard inhibitor compounds. The analog 4b was detected to have the best inhibitory activity against both AChE and BChE enzymes with the lowest IC 50 values as 0.648 µM for AChE and 0.745 µM for BChE. The analyses of enzyme inhibition relationship with the synthesized analogs could help to design new analogs for the inhibitors of cholinergic and glutathione pathways based on the indole derivatives.

Rhodium-Catalyzed Annulation of N-Acetoxyacetanilide with Substituted Alkynes: Conversion of Nitroarenes to Substituted Indoles.

A general and efficient rhodium-catalyzed redox-neutral annulation of N-acetoxyacetanilides, readily accessible from nitroarenes, with alkynes has been accomplished for the synthesis of substituted indole derivatives. A wide range of substituted 2,3-diarylindoles were achieved from various substituted N-acetoxyacetanilides and symmetrical/unsymmetrical alkynes in good to excellent yields. The developed method was successfully integrated with the synthesis of N-acetoxyacetanilides for the efficient one-pot synthesis of indoles from nitroarenes. The important features are the introduction of N-acetoxyacetamide as a new directing group, redox-neutral annulation, an additive-free approach, wide functional group tolerance, an intramolecular version, and a one-pot reaction of nitroarenes. The method was further extended to the synthesis of potent higher analogues of indole, viz., pyrrolo[3,2-f]indoles and dibenzo[a,c]carbazoles. In addition, a plausible mechanism was proposed based on the isolation and stoichiometric study of a potential aryl-Rh intermediate.

Synthesis and Biological Evaluation of (S)-2-(Substituted arylmethyl)-1-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]indole-3-carboxamide Analogs and Their Synergistic Effect against PTEN-Deficient MDA-MB-468 Cells.

A series of twenty-six compounds of furfuryl or benzyl tetrahydropyrazino[1,2-a]indole analogs were synthesized and evaluated for cytotoxic activity against the estrogen receptor (ER)-positive breast cancer cell line (MCF-7) and the epidermal growth factor receptor (EGFR) over-expressed triple-negative breast cancer cell line (MDA-MB-468). Among them, compounds 2b, 2f and 2i showed more potent activity and selectivity against MDA-MB-468 cells than gefitinib, as an EGFR- tyrosine kinase inhibitor. In addition, it was confirmed by means of isobologram analysis of combinational treatment with gefitinib that they have a synergistic effect, especially compounds 2b and 2f, which inhibit Akt T308 phosphorylation. Moreover, it was confirmed that 2-benzyl-1-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]indole-3-carboxamide analogs (2b, 2f, and Ref 2) tend to selectively inhibit PI3Kβ, which is involved in the phosphorylation of Akt.

Green Approach to the Synthesis of New Indole and Benzimidazole Analogs and Their Biological Evaluation

Green Approach to the Synthesis of New Indole and Benzimidazole Analogs and Their Biological Evaluation

Indole diketopiperazine alkaloids and aromatic polyketides from the Antarctic fungus Penicillium sp. SCSIO 05705

A new indole diketopiperazine alkaloid, named penilline D (1), together with five known indole alkaloid analogues (2–5, 11), two meroterpenoids (6 and 12), and four butenolide derivatives (7–10), were isolated from the Antarctic fungus Penicillium sp. SCSIO 05705. Extensive spectroscopic analysis and electronic circular dichroism (ECD) calculation were used to elucidate the structure of penilline D (1), including its absolute configuration. All isolated compounds (1–12) were evaluated for their cytotoxic, antibacterial and enzyme inhibitory activities against acetylcholinesterase (AChE) and pancreatic lipase (PL). Among them, compound 5 exhibited moderate in vitro cytotoxic activity against the 143B cell line with IC50 value of 12.64 ± 0.78 μM. Compound 6 showed strong inhibitory activity against AChE with IC50 value of 0.36 nM (IC50 18.7 nM for Tacrine), while compounds 6 and 11 showed weak PL enzyme inhibitory activity. Furthermore, an in silico molecular docking study was also performed between 6 and AChE.

Carbazole and Simplified Derivatives: Novel Tools toward β-Adrenergic Receptors Targeting

β-Adrenergic receptors (β-ARs) are G protein-coupled receptors involved in important physiological and pathological processes related to blood pressure and cardiac activity. The inhibition of cardiac β1-ARs could be beneficial in myocardial hypertrophy, ischemia and failure. Several carbazole-based compounds have been described as promising β-blockers. Herein, we investigate the capability of a carbazole derivative and three simplified indole analogs to interact with the active binding site of β1-AR by molecular docking studies. In the light of the obtained results, our compounds were tested by biological assays in H9c2 cardiomyocytes exposed to isoproterenol (ISO) to confirm their potential as β1-blockers agents, and two of them (8 and 10) showed interesting and promising properties. In particular, these compounds were effective against ISO-dependent in vitro cardiac hypertrophy, even at concentrations lower than the known β-AR antagonist propranolol. Overall, the data suggest that the indole derivatives 8 and 10 could act as potent β1-blockers and, active at low doses, could elicit limited side effects.

Synthesis of new urease enzyme inhibitors as antiulcer drug and computational study

In search of potent urease inhibitor indole analogues (1–22) were synthesized and evaluated for their urease inhibitory potential. All analogues (1–22) showed a variable degree of inhibitory interaction potential having IC50 value ranging between 0.60 ± 0.05 to 30.90 ± 0.90 µM when compared with standard thiourea having IC50 value 21.86 ± 0.90 µM. Among the synthesized analogues, the compounds 1, 2, 3, 5, 6, 8, 12, 14, 18, 20 and 22 having IC50 value 3.10 ± 0.10, 1.20 ± 0.10, 4.60 ± 0.10, 0.60 ± 0.05, 5.30 ± 0.20, 2.50 ± 0.10, 7.50 ± 0.20, 3.90 ± 0.10, 3.90 ± 0.10, 2.30 ± 0.05 and 0.90 ± 0.05 µM respectively were found many fold better than the standard thiourea. All other analogues showed better urease interaction inhibition. Structure activity relationship (SAR) has been established for all analogues containing different substituents on the phenyl ring. To understand the binding interaction of most active analogues with enzyme active site docking study were performed. Communicated by Ramaswamy H. Sarma

Deciphering structural bases of intestinal and hepatic selectivity in targeting pregnane X receptor with indole-based microbial mimics

Microbial metabolite mimicry is a new concept that promises to deliver compounds that have minimal liabilities and enhanced therapeutic effects in a host. In a previous publication, we have shown that microbial metabolites of L-tryptophan, indoles, when chemically altered, yielded potent anti-inflammatory pregnane X Receptor (PXR)-targeting lead compounds, FKK5 and FKK6, targeting intestinal inflammation. Our aim in this study was to further define structure–activity relationships between indole analogs and PXR, we removed the phenyl-sulfonyl group or replaced the pyridyl residue with imidazolopyridyl of FKK6. Our results showed that while removal of the phenyl-sulfonyl group from FKK6 (now called CVK003) shifts agonist activity away from PXR towards the aryl hydrocarbon receptor (AhR), the imidazolopyridyl addition preserves PXR activity in vitro. However, when these compounds are administered to mice, that unlike the parent molecule, FKK6, they exhibit poor induction of PXR target genes in the intestines and the liver. These data suggest that modifications of FKK6 specifically in the pyridyl moiety can result in compounds with weak PXR activity in vivo. These observations are a significant step forward for understanding the structure–activity relationships (SAR) between indole mimics and receptors, PXR and AhR.

Discovery of novel indole derivatives that inhibit NEDDylation and MAPK pathways against gastric cancer MGC803 cells

A series of novel indole derivatives were synthesized and evaluated for their antiproliferative activity against three selected cancer cell lines (MGC803, EC-109 and PC-3). Among these analogues, 2-(5-methoxy-1H-indol-1-yl)-N-(4-methoxybenzyl)-N-(3,4,5-trimethoxyphenyl)acetamide (V7) showed the best inhibitory activity against MGC803 cells with an IC50 value of 1.59 μM. Cellular mechanisms elucidated that V7 inhibited colony formation, induced apoptosis and arrested cell cycle at G2/M phase. Importantly, indole analogue V7 inhibited NEDDylation pathway and MAPK pathway against MGC803 cells.

Acetyleugenol from Acacia nilotica (L.) Exhibits a Strong Antibacterial Activity and Its Phenyl and Indole Analogues Show a Promising Anti-TB Potential Targeting PknE/B Protein Kinases

Acetyleugenol is a phytochemical compound with broad effects against infectious diseases and tumors. Here, we extracted, characterized, and elucidated the structure of acetyeugenol, for the first time, from the leaves of Acacia nilotica (L.)—a well-known medicinal plant. The broad antibacterial potential of acetyleugenol was first confirmed against seven bacterial clinical isolates, which reveal a strong activity against Proteus sp., Salmonella typhi, Staphylococcus aureus, and Streptococcus pneumonia with similar or better zone of inhibition comparing to that of the control amoxicillin. To further investigate its effect against Mycobacterium tuberculosis, acetyleugenol and its indole and phenyl analogues were subjected to molecular docking experiments against two potential tuberculosis drug targets—MtPknE and MtPknB Ser/Thr protein kinases. The results reveal that all of the analogs have improved docking scores compared to the acetyleugenol. The indole analogues EUG-1 and EUG-3 were more effective with better docking scores for MtPknE with −11.08 and −10.05 kcal/mol, respectively. Similar results were obtained for the MtPknB. In contrast, only the EUG-2 phenyl analogue has given rise to similar docking scores for both targets. This opens the door for further comprehensive studies on these acetyleugenol analogues with in vitro and in vivo experiments to validate and get more insights into their mechanisms of action.