Indole Class Research Articles

Palladium-Catalyzed Tsuji-Trost-Type Reaction of 3-Indolylmethylacetates with O, and S Soft Nucleophiles.

The chemical valorization of widespread molecules in renewable sources is a field of research widely investigated in the last decades. In this context, we envisaged that indole-3-carbinol, present in different Cruciferae plants, could be a readily available building block for the synthesis of various classes of indoles through a palladium-catalyzed Tsuji-Trost-type reaction with O and S soft nucleophiles. The regiochemical outcome of this high-yielding functionalization shows that the nucleophilic substitution occurs only at the benzylic position. Interestingly, with this protocol, the sulfonyl unit could be appended to the indole nucleus, providing convenient access to new classes of molecules with potential bioactivity.

Cyclopenta[b]indoles as novel antimicrotubule agents with antileukemia activity

Acute leukemias present therapeutic challenges despite advances in treatments. Microtubule inhibitors have played a pivotal role in cancer therapy, inspiring exploration into novel compounds like C2E1 from the cyclopenta[b]indole class. In the present study, we investigated C2E1's potential as a therapeutic agent for acute leukemia at molecular, cellular, and genetic levels. C2E1 demonstrated tubulin depolarization activity, significantly reducing leukemia cell viability. Its impact involved multifaceted mechanisms: inducing apoptosis, arrest of cell cycle progression, and inhibition of clonogenicity and migration in leukemia cells. At a molecular level, C2E1 triggered DNA damage, antiproliferative, and apoptosis markers and altered gene expression related to cytoskeletal regulation, disrupting essential cellular processes crucial for leukemia cell survival and proliferation. These findings highlight C2E1's promise as a potential candidate for novel anti-cancer therapies. Notably, its distinct mode of action from conventional microtubule-targeting drugs suggests the potential to bypass common resistance mechanisms encountered with existing treatments. In summary, C2E1 emerges as a compelling compound with diverse effects on leukemia cells, showcasing promising antineoplastic properties. Its ability to disrupt critical cellular functions selective to leukemia cells positions it as a candidate for future therapeutic development.

Intestinal flora, intestinal metabolism, and intestinal immunity changes in complete Freud's adjuvant-rheumatoid arthritis C57BL/6 mice

Rheumatoid arthritis (RA) is an inflammatory-mediated autoimmune disease characterized by persistent joint enlargement, synovial cartilage damage, and inflammatory infiltrates. Although the pathogenesis and treatment of RA are still currently insufficient, the importance of the intestine flora, metabolism and immunity for RA has been gradually recognized, and many intestine regulatory strategies have been used to treat RA. However, the relationship between RA and intestine flora, metabolism and immunity has not been fully expounded. In this study, Complete Freund's Adjuvant (CFA) was used to establish RA model, CyTOF technology was used to study the changes of intestinal immune cell types, 16S rRNA technology was used to analyze the differences of intestinal flora, and LC-MS technology was used to explain the effects of metabolites produced by the changed intestinal flora on RA. Moreover, we systematically explored how the imbalance of intestinal flora changed the intestinal immune status through its metabolites in RA mice. Our results showed that the intestinal flora of RA mice changed significantly, and the bacteria producing short-chain fatty acids (SCFAs), indole classes and secondary bile acids were significantly reduced. The abundance of SCFAs, indole classes and secondary bile acids in the intestine were significantly decreased. The balance of immune cells in the intestine of RA mice was significantly disrupted, with an overall decrease in immune cells. This work reveals the possible relationship between intestinal flora, metabolism and immunity and RA in mice, which will provide new therapeutic strategies for RA.

Drug Design, Molecular Docking and Molecular Dynamics Simulations of Indole Class HIV‐1 NNRTIs Explored with QSAR and Topomer Search

AbstractHIV reverse transcriptase (RT) as one of the key targets for the treatment of HIV, and in recent years a series of indole class non‐nucleoside reverse transcriptase inhibitors (NNRTIs) with potent anti‐HIV‐1 properties have been reported. In this paper, Topomer CoMFA model with reliable validation results (q2=0.809, R2=0.983, R2pred=0.870) for exploring the quantitative structure‐activity relationship (QSAR) of the inhibitors. And the relationship between molecular structures and activities were further analysed using the contour plots. The Topomer search technique was employed to search and then designed novel compounds with stronger inhibitory effects. Molecular docking showed that the residue LYS101, GLU138 and ILE180 played a key role, meanwhile, the stability of the docking results was verified by molecular dynamics simulations (MD). Finally, the calculated results of the binding free energy calculations agree with the predictions of the model, further validating the reliability of the proposed model.

DEVELOPMENT OF NOVEL SUBSTITUTED INDOLE MOLECULES AS POTENTIAL NAV1.7 INHIBITORS

Pain is often defined as a single form of the nervous system for abnormal things in the human body. Neuropathic pain is a type of pain that is a consequence of nerve damage and usually, it is a chronic type. Sodium Channel 1.7 (Nav 1.7) is an upcoming target for neuropathic pain management. Several heterocyclic compounds are reported for potentials against neuropathic pain. 24 different heterocyclic derivatives from substituted indole class were synthesized and virtually analyzed against Nav 1.7 for inhibition potential. The developed substituted indole was confirmed via spectral analysis and showed excellent binding ability with Nav 1.7, which can be further explored for biological activity for the development of potential Nav 1.7 inhibitors with excellent activity against Neuropathic pain.

Direct Access to Functionalized Indoles via Single Electron Oxidation Induced Coupling of Diarylamines with 1,3-Dicarbonyl Compounds.

Under aerobic copper catalysis, an unprecedented direct synthesis of functionalized indoles via single electron oxidation induced coupling of diarylamines with 1,3-dicarbonyl compounds is presented. The protocol proceeds with good functional group and substrate compatibility, the use of readily available feedstocks and naturally abundant catalyst system, high step and atom efficiency, as well as selectivity, which offers a platform for accessing a new class of indoles with the potential for the discovery of functional molecules.

Synthesis and in vitro anti-proliferative capabilities of steroidal thiazole and indole derivatives

Derivatives (1–15) of steroidal and indole class were synthesized using different strategies. These compounds were characterized by 1H NMR spectroscopy and EI-MS, respectively. The synthetic derivatives were examined for their cytotoxic effects on human adenocarcinoma cells (HCT-116) using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and morphometric analysis. The cytotoxic effects of all the compounds were observed after 48 h treatment and it was found that out of fifteen, four compounds 1, 2, 3, and 14 showed inhibitory action on the cancer cells. We have calculated the IC50 values for compounds 1, 2, 3, and 14 which were 22.50 µg/mL, 55.65 µg/mL, 21.35 µg/mL and 58.50 µg/mL, respectively. The compounds 3 (IC50 = 21.35 µg/mL) and 1 (IC50 = 22.50 µg/mL) showed highest inhibitory activities as compared to compounds 2 (IC50 = 55.65 µg/mL) and 14 (IC50 = 58.50 µg/mL). These results suggested that steroidal thiazole and indole derivatives are potent lead molecules having strong anti-cancer proliferative capabilities.

LC-ESI-MS/MS profiling of alkaloids and antiproliferative activity of Pachypoduim lamerei drake leaves

In the present study, evaluation of the antiproliferative activity of Pachypodium lamerei Drake leaves (family Apocyaceae) against human breast cancer cell lines MDA-MB-231 was done for the total methanolic extract, crude alkaloidal mixture and ursolic acid using the MTT colorimetric assay. The methanolic extract showed the strongest antiproliferative activity followed by ursolic acid and crude alkaloidal fraction with an IC50 equal to 6.2, 14.55 and 56.3 µg/ml respectively compared to oleocanthal. It is the first record for the LC/ESI-MS/MS alkaloidal profiling of the leaves of P. lamerei. Seven alkaloids were tentatively identified according to their fragmentation patterns. Four alkaloids were related to the parent indole class and two alkaloids belong to the quinoline class in addition to one steroidal alkaloid with a pregnan nucleus. Phytochemical investigation of the methanolic extract led to the isolation of three triterpenoidal compounds including ursolic acid, 11,12-didehydroursolic acid lactone and ursolic acid lactone.

Synthesis, Biological Evaluation and Modeling Studies of New Pyrido[3,4-b]indole Derivatives as Broad-Spectrum Potent Anticancer Agents.

ObjectiveThere is an urgent need drugs against particularly difficult to treat solid tumors such as pancreatic, triple negative breast, lung, colon, metastatic prostate cancers and melanoma. Thus, the objective of this study was to synthesize compounds based computational modeling that indicated the pyrido[3,4-b]indole class bind to MDM2, a new cancer target for which there are still no drug on the market.MethodsCompounds were synthesized by established methods and tested for antiproliferative activity against a broad range of human cancer cell lines, comprising HCT116 colon, HPAC, MIA PaCa-2 and Panc-1 pancreatic, MCF-7 and MDA-MB-468 breast, A375 and WM164 melanoma, A549 lung, and LNCaP, DU145 and PC3 prostate cancer lines. Computational docking was also undertaken.ResultsThe novel pyrido[3,4-b]indoles synthesized exhibited a clear SAR with regards to antiproliferative activity, with potent broad-spectrum anticancer activity with IC50s down to 80, 130, 130 and 200 nM for breast, colon, melanoma and pancreatic cancer cells, respectively. 1-Naphthyl at C1 combined with methoxy at C6 provided the best antiproliferative activity. Thus, compound 11 (1-naphthyl-6-methoxy-9H-pyrido[3,4-b]indole) showed the highest potency. A mechanistic feature of the compounds as a group is a strongly selective G2/M cell cycle phase arrest. Docking at on MDM2 suggested a hydrogen bond interaction between the 6-methoxy Tyr106, hydrophobic interaction with Val93, pi-pi stacking interactions with Tyr100 and His96 and hydrophobic interactions with Leu54 and Ile99. An N9-methyl group disrupted binding interactions, such as H-bond interactions involving the N9 hydrogen.ConclusionWe have identified a novel series of pyrido[3,4-b]indoles with potent broad spectrum anticancer activity towards the most aggressive and difficult to treat cancers including metastatic pancreatic cancer, non-small cell lung cancer, triple negative breast cancers, and BRAFV600E mutant melanoma, as well as metastatic colon and prostate cancers. There was also evidence of selectivity towards cancer cells relative to normal cells. These compounds will serve as new leads from which novel therapeutics and molecular tools can be developed for a wide variety of cancers.

Alternative core development around the tetracyclic indole class of HCV NS5A inhibitors

Herein, we describe our research efforts to develop unique cores in molecules which function as HCV nonstructural protein 5A (NS5A) inhibitors. In particular, various fused tetracyclic cores were identified which showed genotype and mutant activities comparable to the indole-based tetracyclic core.

Indole Molecules as Inhibitors of Tubulin Polymerization: Potential New Anticancer Agents, an Update (2013–2015)

Discovery of new indole-based tubulin polymerization inhibitors will continue to dominate the synthetic efforts of many medicinal chemists working in the field. The indole ring system is an essential part of several tubulin inhibitors identified in the recent years. The present review article will update the synthesis, anticancer and tubulin inhibition activities of several important new indole classes such as 2-phenylindoles (28, 29 & 30), oxindoles (35 & 38), indole-3-acrylamides (44), indolines (46), aroylindoles (49), carbozoles (75, 76 & 82), azacarbolines (87) and annulated indoles (100-105).

Matched and mixed cap derivatives in the tetracyclic indole class of HCV NS5A inhibitors

A matched and mixed capping SAR study was conducted on the tetracyclic indole class of HCV NS5A inhibitors to examine the influence of modifications of this region on the overall HCV virologic resistance profiles.

General asymmetric synthesis of 2,2,2-trifluoro-1-(1H-indol-3- and -2-yl)ethanamines

This work describes an asymmetric functionalization of the pyrrole ring of an indole structure with (2,2,2-trifluoro)ethylamine moiety allowing for general access to two novel classes of trifluoromethyl-containing indoles. We found that under the Friedel–Crafts reaction conditions (S)-N-tert-butylsulfinyl-3,3,3-trifluoroacetaldimine (1) easily reacts with indole derivatives affording the target 3-substituted products, while LDA-promoted reactions proceed exclusively at the 2-position. We demonstrate that both approaches feature wide substrate scope, high chemical yields and diastereoselectivities, which render these reactions readily applicable for straightforward preparation of biologically interesting compounds containing chiral CF3CH(NH2) and indole groups. The mechanistic rationales accounting for the observed mode of stereochemical preferences are proposed.

Rh(III)-catalyzed redox-neutral C-H activation of pyrazolones: an economical approach for the synthesis of N-substituted indoles.

A new strategy is reported for the economical synthesis of indoles bearing an N-(3-aminobut-2-enoyl) substituent through Rh(III)-catalyzed redox-neutral C-H activation of pyrazolones and alkynes. This approach utilizes cheap substrates and mild reaction conditions to access a unique class of indoles via a N-N bond oxidative cleavage without loss of the N-terminus, therefore meeting all the atom/step/redox economy principles.

RK-270A-C, new oxindole derivatives isolated from a microbial metabolites fraction library of Streptomyces sp. RK85-270.

Three new oxindole derivatives, RK-270A (1), B (2) and C (3) (Figure 1), were discovered and isolated from Streptomyces sp. RK85-270. They had an isopropylidene group at C-3 position of an oxindole skeleton, and C-1 also had a prenyl group and belonged to a class of 6-prenylated indoles. The isolation of this type of indoles was the first example as a natural product. Their cytotoxicity and antibacterial activities were evaluated.

Identification of Alkaloid’s Profile in Ficus benjamina L. Extracts with Higher Antioxidant Power

Different classes of known alkaloid compounds were identified for the first time in leaves and barks of Ficus benjamina L. from Moraceae family. The identification of 28 alkaloids in F. benjamina leaves and 14 alkaloids in its barks was identified using chromatographic analysis as Gas Chromatography associated to Mass Spectrometry (GC-MS). This characterization analysis allows to verifying the presence of different alkaloids type-classes in both leaves and barks, such as isoquinoline class, indole class and quinolizidine class. The quantification results are deduced by analysis with spectrophotometric assay, using a calibration curve of boldine as standard alkaloid that reveals the presence of 26 ± 0.1 μg of alkaloids boldine equivalent in 1 gram of F. benjamina leaves and 3.8 ± 0.1 μg alkaloids boldine equivalent in 1 gram of its barks. A significant correlation was observed between the total alkaloid content of crude extracts and 2,2-diphenyl-1-picrylhydrazyl assay (DPPH), suggesting that the level of antioxidant activity in this species is strongly correlated to the alkaloid content. These findings should provide useful information for future on the pharmaceutical properties of these alkaloids from F. benjamina.

Alkaloids as a source of potential anticholinesterase inhibitors for the treatment of Alzheimer's disease

The inhibition of acetylcholinesterase (AChE), the key enzyme in the breakdown of acetylcholine, is currently the main pharmacological strategy available for Alzheimer's disease (AD). In this sense, many alkaloids isolated from natural sources, such as physostigmine, have been long recognized as acetyl- and butyrylcholinesterase (BChE) inhibitors. Since the approval of galantamine for the treatment of AD patients, the search for new anticholinesterase alkaloids has escalated, leading to promising candidates such as huperzine A. This review aims to summarize recent advances in current knowledge on alkaloids as AChE and BChE inhibitors, highlighting structure-activity relationship (SAR) and docking studies. Natural alkaloids belonging to the steroidal/triterpenoidal, quinolizidine, isoquinoline and indole classes, mainly distributed within Buxaceae, Amaryllidaceae and Lycopodiaceae, are considered important sources of alkaloids with anti-enzymatic properties. Investigations into the possible SARs for some active compounds are based on molecular modelling studies, predicting the mode of interaction of the molecules with amino acid residues in the active site of the enzymes. Following this view, an increasing interest in achieving more potent and effective analogues makes alkaloids good chemical templates for the development of new cholinesterase inhibitors. The anticholinesterase activity of alkaloids, together with their structural diversity and physicochemical properties, makes them good candidate agents for the treatment of AD.

ChemInform Abstract: BN Isosteres of Indole

AbstractReview: 41 refs.

BN isosteres of indole.

Indole is a heterocycle of great importance to biological systems and materials applications. Synthesis of indole and its derivatives has been a major focus of research for over a century. BN/CC isosterism is an emerging strategy for expanding the structural diversity of indole-based compounds. Two classes of BN indoles have been reported to date: the well-studied "external" BN indoles (or 1,3,2-benzodiazaborolines), and the recently reported "fused" BN indoles. This perspective presents the history of both classes of indole isosteres, with a general overview of their synthesis, functionalization, and properties.

Indole Molecules As Inhibitors Of Tubulin Polymerization: Potential New Anticancer Agents

Agents that interfere with tubulin function have a broad anti-tumor spectrum and they represent one of the most significant classes of anticancer agents. In the past few years, several small synthetic molecules that have an indole nucleus as a core structure have been identified as tubulin inhibitors. Among these, several aroylindoles, arylthioindoles, diarylindoles and indolylglyoxyamides have shown good inhibition towards the tubulin polymerization. This article reviews the synthesis, biological activities and SARs of these main classes of indoles. Brief mention has also been made about the fused indole analogs as tubulin inhibitors.