Novel N-substituted indole hydrazones as potential antiplatelet agents: synthesis, biological evaluations, and molecular docking studies

Background and purpose:

Antiplatelet agents can diminish the chance of coronary heart diseases due to the prevention of unusual clotting in the arteries by inhibiting platelet aggregation and avoiding the formation of a blood clot. This mechanism can help to prevent ischemic stroke likewise. To improve the activity of these drugs and reduce their side effects, further studies are required.

Experimental approach:

Based on the previous studies representing the promising antiplatelet activity of indole hydrazones, a series of their homologs containing twenty-one compounds were prepared in two steps. First, alkylation reaction on the nitrogen of the indole ring, and second, chiff base formation by condensation of a primary amine and N-substituted indole-3 carbaldehyde. Consequently, their platelet anti-aggregation activity was evaluated based on the Born turbidimetric method.

Findings/Results:

Most of the compounds exhibited noticeable activity against platelet aggregation induced by arachidonic acid. Amongst them, two compounds 2e and 2f showed higher activity with IC₅₀ values that made comparable to indomethacin and acetylsalicylic acid as standard drugs and had no toxicity on platelets.

Conclusion and implications:

The synthesized compounds exhibited promising activity against arachidonic acid-induced aggregation; however, none of them showed noticeable antiplatelet activity induced by adenosine di-phosphate. Chemical structure comparison of the prepared derivatives indicated the existence of a lipophilic medium-sized group on the phenyl ring increased their activity. In addition, the docking studies confirmed this hydrophobic interaction in the lipophilic pocket of cyclooxygenase-1 enzyme suggesting that hydrophobicity of this region plays a pivotal role in the anti-platelet activity of these compounds. To prove this finding, the enzymatic evaluation with the target enzyme is required.

Synthesis and biological evaluation of indole-based peptidomimetics as antibacterial agents against Gram-positive bacteria

The emergence of bacterial multidrug resistance and the lack of new antimicrobial agents urgently demand the discovery and development of novel antibacterials that avoid bacterial resistance. Antimicrobial peptidomimetics represent a promising approach for overcoming antibiotic resistance. Herein we report the synthesis and evaluation of indole-based amphiphilic antimicrobial peptidomimetics, bearing hydrophobic side chains and hydrophilic cationic moieties. Among these derivatives, compound 28 demonstrated potent antimicrobial activity against Gram-positive bacteria, low hemolytic activity and low toxicity towards mammalian cells, as well as good stability in salt conditions. Moreover, compound 28 showed the rapid killing of bacteria via membrane-targeting action without developing bacterial resistance. More importantly, compound 28 displayed high antimicrobial potency against Gram-positive bacteria in a murine model of bacterial keratitis, and was found to be more efficient than vancomycin. Thus, compound 28 had great potential as a promising lead compound for the treatment of Gram-positive bacterial infection.

Preparation of G-CuO NPs and G-ZnO NPs with mallow leaves, investigation of their antibacterial behavior and synthesis of bis(indolyl)methane compounds under solvent-free microwave assisted dry milling conditions using G-CuO NPs as a catalyst

In this study, biogenic copper and zinc oxide nanoparticles (G-ZnONPs and G-CuONPs) were synthesized by the green synthesis method using Malva parviflora L. (Millow) leaf extract and the obtained nanoparticles were characterized in detail with UV-Vis, FTIR, SEM, XRD. The antibacterial properties of the synthesized nanoparticles on gram-positive and gram-negative bacteria were investigated and it was found that the nanoparticles had high antimicrobial activity in the results of the experiments. With the obtained G-CuONPs, the synthesis of bis(indolyl)methanes with the "green" one-pot synthesis using microwave was achieved quickly and with high efficiency, and the thermal behavior of the obtained products was investigated.

Identification and functional characterization of olfactory indolergic receptors in Drosophila melanogaster

Indole-sensitive odorant receptors or indolORs belong to a mosquito-specific expansion as ancient as the Culicidae lineage. Brachyceran flies appeared to lack representative members of this group despite the importance of indolics in this important group of dipterans. To explore whether indolORs occur in other brachyceran species, we searched for candidate indolORs in Drosophila melanogaster. Using phylogenetic tools, we show that D. melanogaster OR30a, OR43a, and OR49b form a distinct monophyletic lineage with mosquito indolORs. To explore a potential functional orthology with indolORs, we expressed these three Drosophila ORs in Xenopus laevis oocytes and measured their responses to a panel of indolic compounds. We provide evidence that OR30a, OR43a, and OR49b exhibit high sensitivity to indoles. Along with the recent discovery of indolORs in the housefly Musca domestica, our findings suggest that indolORs are a widespread feature of the peripheral olfactory systems of Diptera.

Identification and functional characterization of olfactory indolergic receptors in Musca domestica

In mosquitoes, indolic compounds are detected by a group of olfactory indolergic Odorant Receptors (indolORs). The ancient origin of indole and 3-methylindole as chemical signals suggest that they may be detected by insects outside the Culicidae clade. To test this hypothesis, we have identified potential indolOR genes in brachyceran flies based on sequence homology. Because of the crucial roles of indolic compounds in oviposition and foraging, we have focused our attention on the housefly Musca domestica. Using a heterologous expression system, we have identified indolOR transcript expression in the female antennae, and have characterized MdomOR30a and MdomOR49b as 3-methylindole and indole receptors, respectively. We have identified a set of 92 putative indolOR genes encoded in the genomes of Culicoidea, Psychodidae and brachycera, described their phylogenetic relationships, and exon/intron structures. Further characterization of indolORs will impact our understanding of insect chemical ecology and will provide targets for the development of novel odor-based tools that can be integrated into existing vector surveillance and control programs.

A simple method for obtaining human albumin and its use for in vitro interaction assays with indole-thiazole and indole-thiazolidinone derivatives

This work aimed to develop a simple and low-cost method to obtain human serum albumin (HSA) and its consequent application for in vitro drug interaction assays. The HSA was purified by classic principles of plasma precipitation and thermocoagulation, using a multiple-stage fractionation. The quality of the final product was assessed by electrophoresis, protein dosage by the Lowry method and the pharmacopeial thermal stability. At the end, an isotonic solution of HSA with a total protein concentration of 2.7 mg·mL^-1 was obtained, which was visualized as a single band corresponding to the molecular weight of 66 kDa. After the thermal stability test, there was no indication of turbidity or color change of the solution. Finally, the HSA was useful for interaction assays with indole-thiazole and indole-thiazolidinone derivatives through UV-vis absorption and fluorescence spectroscopic studies, as well as by docking molecular analysis. Derivatives quenched the intrinsic fluorescence of HSA, disrupted the tryptophan residues microenvironment, and probably bind at Sudlow's site I. Therefore, the simplified methodology developed in this work proved to be effective in obtaining HSA that can be applied to research goals including drug interaction assays.

Syntheses of 1H-Indoles, Quinolines, and 6-Membered Aromatic N-Heterocycle-Fused Scaffolds via Palladium(II)-Catalyzed Aerobic Dehydrogenation under Alkoxide-Free Conditions

Aromatic N-heterocycle-fused scaffolds such as indoles and quinolines are important core structures found in various bioactive natural products and synthetic compounds. Recently, various dehydrogenation methods with the help of alkoxides, known to significantly promote dihydro- or tetrahydro-heterocycles to be oxidized, were developed for the heterocycle synthesis. However, these approaches are sometimes unsuitable due to resulting undesired side reactions such as reductive dehalogenation. Herein, expedient syntheses of 1H-indoles, quinolines, and 6-membered N-heterocycle-fused scaffolds from their hydrogenated forms through palladium(II)-catalyzed aerobic dehydrogenation under alkoxide-free conditions are reported. A total of 48 compounds were successfully synthesized with a wide range of functional groups including halogens (up to 99% yield). These methodologies provide facile routes for various privileged structures possessing aromatic N-heterocycles without the help of alkoxides, in highly efficient manners.

Amberlyst-15 catalysed synthesis of novel indole derivatives under ultrasound irradiation: Their evaluation as serotonin 5-HT2C receptor agonists

A series of indole based novel Schiff bases was designed as potential agonists of 5-HT_2C receptor that was supported by docking studies in silico. These compounds were synthesized via Amberlyst-15 catalysed condensation of an appropriate pyrazole based primary amine with the corresponding indole-3-aldehyde under ultrasound irradiation at ambient temperature. A number of target Schiff bases were obtained in good yields (77-87%) under mild conditions within 1 h. Notably, the methodology afforded the corresponding pyrazolo[4,3-d]pyrimidin-7(4H)-one derivatives when the primary amine was replaced by a secondary amine. Several Schiff bases showed agonist activity when tested against human 5-HT_2C using luciferase assay in HEK293T cells in vitro. The SAR (Structure-Activity-Relationship) studies suggested that the imine moiety was more favorable over its cyclic form i.e. the corresponding pyrazolopyrimidinone ring. The Schiff bases 3b (EC₅₀ 1.8 nM) and 3i (EC₅₀ 5.7 nM) were identified as the most active compounds and were comparable with Lorcaserin (EC₅₀ 8.5 nM). Also like Lorcaserin, none of these compounds were found to be PAM of 5-HT_2C. With ∼24 and ∼150 fold selectivity towards 5-HT_2C over 5-HT_2A and 5-HT_2B respectively the compound 3i that reduced locomotor activity in zebrafish (Danio rerio) larvae model emerged as a promising hit molecule for further study.

Quantum mechanical, virtual screening, molecular docking, molecular dynamics, ADME and antimicrobial activity studies of some new indole-hydrazone derivatives as potent agents against E. faecalis

In this study, a new series of indole-5-carbaldehyde hydrazone derivative compounds were designed, synthesized, and their antimicrobial activities were determined by the microdilution method, and the in vitro cytotoxic effects on Beas-2b cell lines were investigated by MTT assay. When the activity results were examined, 5i12 showed promising activity against E. faecalis with MIC: 2 µg/mL compared to ampicillin, gentamicin, and vancomycin, although the antimicrobial activities of the indole derivatives were generally weaker than those of the standard drugs. Compounds showed no cytotoxic activity on the A549, MCF-7, and Beas-2b cell lines. Molecular docking studies were performed on 15 different proteins to understand the mechanism of 5i12's good antimicrobial action against E. faecalis, and it was concluded that the compounds interacted with FabH, not enough other protein structures. Molecular dynamics simulations were performed to investigate the protein-ligand stability of the most active compound against E. faecalis. The RMSD value of 5i12 varied between 0.02 and 0.16 nm during the MD simulation. The apoprotein peaked at 0.55 nm at the beginning of the simulation and stabilized below 0.5 nm. The theoretical ADME profiles of all compounds were calculated and found to comply with Lipinski and other limiting rules. In addition, some theoretical quantum parameters (HOMO-LUMO) of compounds, and both MEP analysis and geometric optimization analysis for 5i12 were calculated using the 6-311 G (d,p) base set and DFT/B3LYP theory, and the results were visualized. Communicated by Ramaswamy H. Sarma.

Design, synthesis and biological evaluation of novel deoxyvasicinone-indole as multi-target agents for Alzheimer's disease

In this study, a series of multifunctional hybrids (6a-6l) against Alzheimer's disease were designed and obtained by conjugating the pharmacophores of deoxyvasicinone and indole. These analogs of deoxyvasicinone-indole were evaluated as inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), and as inhibitors of amyloid aggregation (Aβ_1-42) for treatment of Alzheimer's disease (AD). Subsequently, AChE induced Aβ aggregation inhibition test was also performed for selected compounds. Biological activity results demonstrated that compound 6b was the most potent and balanced dual ChEs inhibitor with IC₅₀ values 0.12 µM and 0.15 µM for eeAChE and eqBuChE, respectively. Kinetic analysis and docking study indicated that compound 6b was a mixed-type inhibitor for both AChE and BuChE. Compound 6b also found to be the best inhibitors of self-induced Aβ_1-42 aggregation with IC₅₀ values of 1.21 µM. Compound 6b also afforded excellent inhibition of AChE-induced Aβ_1-42 aggregation by 81.1%. Overall, these results indicate that 6b may be considered as lead compound for the development of highly effective anti-AD drugs.

Design, synthesis, stereochemical determination, molecular docking study, in silico pre-ADMET prediction and anti-proliferative activities of indole-pyrimidine derivatives as Mcl-1 inhibitors

In this study, fourteen novel indole-pyrimidine hybrids were designed and synthesized. Their chemical structures were confirmed using different spectroscopic techniques (¹H NMR, ¹³C NMR, IR and mass). Their (E) stereochemical configuration was determined theoretically (MM2 property) and experimentally using 2D NMR technique (NOESY experiment). The prepared compounds were subjected to preliminary biological studies as Mcl-1 inhibitors. Most of the compounds exhibited good abilities for targeting Mcl-1 protein, especially, 7d, 7e, 7i and 7k (K_i = 11.19-15.21 nM). These derivatives were further evaluated against Bcl-XL and Bcl-2 proteins. Some compounds were found to have dual Mcl-1/Bcl-XL such as 7i, or Bcl-XL/Bcl-2 inhibitory activity as 7d. The most potent derivatives as Mcl-1 inhibitors were chosen as representative examples for determination of in-vitro anti-proliferative activity against PC-3, K-562 and MDA-MB-231 cell lines. They possessed excellent to good anti-proliferative activities. All of the synthesized compounds were docked into Mcl-1 active site. Drug-likeness properties and in silico pre-ADMET characters were also predicted.

3-Alkenyl-2-oxindoles: Synthesis, antiproliferative and antiviral properties against SARS-CoV-2

Sets of 3-alkenyl-2-oxindoles (6,10,13) were synthesized in a facile synthetic pathway through acid dehydration (EtOH/HCl) of the corresponding 3-hydroxy-2-oxoindolines (5,9,12). Single crystal (10a,c) and powder (12a,26f) X-ray studies supported the structures. Compounds 6c and 10b are the most effective agents synthesized (about 3.4, 3.3 folds, respectively) against PaCa2 (pancreatic) cancer cell line relative to the standard reference used (Sunitinib). Additionally, compound 10b reveals antiproliferative properties against MCF7 (breast) cancer cell with IC₅₀ close to that of Sunitinib. CAM testing reveals that compounds 6 and 10 demonstrated qualitative and quantitative decreases in blood vessel count and diameter with efficacy comparable to that of Sunitinib, supporting their anti-angiogenic properties. Kinase inhibitory properties support their multi-targeted inhibitory activities against VEGFR-2 and c-kit in similar behavior to that of Sunitinib. Cell cycle analysis studies utilizing MCF7 exhibit that compound 6b arrests the cell cycle at G1/S phase while, 10b reveals accumulation of the tested cell at S phase. Compounds 6a and 10b reveal potent antiviral properties against SARS-CoV-2 with high selectivity index relative to the standards (hydroxychloroquine, chloroquine). Safe profile of the potent synthesized agents, against normal cells (VERO-E6, RPE1), support the possible development of better hits based on the attained observations.

Indole Derivatives as Anti-Tubercular Agents: An Overview on their Synthesis and Biological Activities

BACKGROUND

The indole framework is considered as one of the privileged structures in the area of medicinal chemistry and drug discovery because compounds containing this framework have shown to possess a remarkable ability to bind with many receptors or proteins with high affinity. It is therefore not surprising that the indole nucleus is a frequently found moiety in many bioactive agents or drugs. Indole derivatives have also been explored or studied for their anti-tubercular properties for a long time. The growth inhibition of Mycobacterium tuberculosis (MTB) in vitro and in vivo by the gut microbiota metabolite indole propionic acid (IPA) is one of the recent examples. Notably, tuberculosis (TB), an intractable disease and a major cause of death worldwide, has caused an alarming rise in the number of TB cases recently because of two main reasons, i.e., a several-fold rise among HIV-infected patients and increased drug resistance by some bacterial strains. Thus, the identification of new agents or potential drugs against TB is urgently needed.

METHODS

While the specific pharmacological target or mechanism of action (MOA) for antitubercular activities has been reported for many indole derivatives, the MOA is not well defined or known for a number of indole derivatives though they were found to be active against MTB. In the current review article, we have focused on both types of indole derivatives that have shown activities against MTB. The indoles with known MOA are further segregated based on this pharmacological target reported or indicated whereas other indoles are classified based on the type of anti-TB properties shown by them. The literature for the last 20 years as well as related to up to date knowledge and information was searched on Pubmed, Google Scholar, MEDLINE, and various other databases until August 2020.

RESULTS

A diverse range of functionalized indole derivatives, such as indole-based alkaloids, simple indoles, fused indoles, amide/peptide derivatives of indole, isatin derivatives, etc., have been reported to possess anti-tubercular activities. The anti-tubercular activities, in silico studies (if reported) and the chemical syntheses (in most of the cases) of representative indole derivatives are presented briefly in the current article. The papers referenced by this review allow a deep analysis of the status of the indole-based anti-tubercular agents explored over the past two decades.

CONCLUSION

This review aims at stimulating renewed interest and effort in the discovery and development of new indole-based agents or potential drugs for the treatment of TB. The emergence of modern methods, especially those based on transition metal-catalyzed reactions, has opened up tremendous opportunities in the area of indole synthesis. The desired goal would be to have utilized these modern methodologies for the identification of potent and promising agents to fight against MTB.

Fluorescein Based Three-channel Probe for the Selective and Sensitive Detection of CO32- Ions in an Aqueous Environment and Real Water Samples

We have constructed a novel fluorescein-based fluorescent chemosensor, FL-In, functionalised with an indole moiety and capable of sensing by both the optical "turn-on" and electrochemical detection of carbonate ions (CO₃^2-) in aqueous media. The probe exhibits excellent selectivity and a low detection limit (0.27 µM) regarding carbonate ions by a possible coordination and hydrolysis reaction mechanism. The developed probe successfully detected CO₃^2- ions in different samples of water. Also, in a simple filter paper experiment, we documented its ability to allow the monitoring of CO₃^2- with the naked eye.

Recent Development in Indole Derivatives as Anticancer Agent: A Mechanistic Approach

BACKGROUND

Cancer accounts for several deaths each year. There are multiple FDA approved drugs for cancer treatments. Due to the severe side effects and multiple drug resistance, the current drug therapies become ineffective. So, the newer moieties with fewer toxic effects are necessary for the development.

OBJECTIVE

The mechanism of indole derivatives as anti-cancer agents with their major target is explored in detail in this article.

METHODS

Recent advances and mechanism of indole derivatives as anti-cancer agents are reviewed. This review suggests a detailed explanation of multiple mechanisms of action of various indole derivatives: cell cycle arrest, aromatase inhibitor estrogen receptor regulator, tubulin inhibitor, a tyrosine kinase inhibitor, topoisomerase inhibitors, and NFkB/PI3/Akt/mTOR pathway inhibitors, through which these derivatives have shown promising anti-cancer potential.

RESULTS

A full literature review showed that the indole derivatives are associated with the properties of inducing apoptosis, aromatase inhibition, regulation of estrogen receptor and inhibition of tyrosine kinase, tubulin assembly, NFkB/PI3/Akt/mTOR pathway, and HDACs. These derivatives have shown significant activity against cancer cell lines.

CONCLUSION

Indole derivatives seem to be important in cancer via acting through various mechanisms. This review has shown that the indole derivatives can further be explored for the betterment of cancer treatment, and to discover the hidden potential of indole derivatives.

Green synthesis of some 3-(α,α-diarylmethyl)indoles by bio-nanocomposite from embedding L-histidinium trichloroacetate ionic liquid on functionalized magnetite (L-His+CCl3CO2-@PEG@SiO2-nano Fe3O4)

In this research, a new multilayered magnetized bio-nanocomposite has been prepared. At first, the amino acid-based ionic liquid was obtained from L-histidine and trichloroacetic acid (L-His⁺CCl₃CO₂^-), embedded on the polyethylene glycol-functionalized silicated-nanomagnetite, to prepare the final nanostructure (L-His⁺CCl₃CO₂^-@PEG@SiO₂-nano Fe₃O₄). The bio-nanocomposite was characterized by several techniques such as FT-IR, FESEM, TGA/DTG, EDAX, TEM, VSM, and XRD. The catalytic activity of the core-shell nanostructure was examined in one-pot three-component reaction between aryl aldehydes, indoles, and β-naphthol/phenols to get some new 3-(α,α-diarylmethyl)indoles under solvent-free conditions at 75 °C. Eco-friendly protocol in the absence of hazardous solvents, no observation of by-products such as bis(indolyl)methanes (BIMs), in addition to recovery and reusability of the nanostructure within 3 runs without activity loss are some highlighted notable features of the work. The reused bio-nanocomposite was also characterized through FESEM technique.

N-doped ZnO as an efficient photocatalyst for thiocyanation of indoles and phenols under visible-light

In this study, nitrogen-doped ZnO nanorods (N-ZnO NRs) were synthesized via a very simple hydrothermal process, fully characterized, and this photocatalyst was successfully exploited in thiocyanation reactions of indoles and phenols at room temperature under visible light irradiation. Two important classes of aromatic compounds indoles, and phenols using N-ZnO NRs as photocatalyst treated with ammonium thiocyanate as thiocyanation agent formed the corresponding thiocyano compounds in good yields. Nitrogen is one of the most appropriate p-type dopants that is nontoxic, similar to the atomic radius to oxygen, and lower electronegativity and ionization energy than the O atom. Therefore, the N doping converts ZnO into the p-type ZnO semiconductor structure. This potent, simple, and versatile protocol afforded thiocyanation reactions of indole and phenols under visible light. The reactions proceeded through a radical pathway by applying air molecular oxygen as a low cost and environmentally friendly terminal oxidant. The proposed mechanism based on control experiments was thoroughly described.

Expanding the Substrate Scope of Nitrating Cytochrome P450 TxtE by Active Site Engineering of a Reductase Fusion

Aromatic nitration reactions are a cornerstone of organic chemistry, but are challenging to scale due to corrosive reagents and elevated temperatures. The cytochrome P450 TxtE nitrates the indole 4-position of l-tryptophan at room temperature using NO, O2 and NADPH, and has potential to be developed into a useful aromatic nitration biocatalyst. However, its narrow substrate scope (requiring both the α-amino acid and indole functionalities) have hindered this. Screening of an R59 mutant library of a TxtE-reductase fusion protein identified a variant (R59C) that nitrates tryptamine, which is not accepted by native TxtE. This variant exhibits a broader substrate scope than the wild type enzyme and is able to nitrate a range of tryptamine analogues, with significant alterations to the aromatic and aminoethyl moieties.

Intestinal interplay of quorum sensing molecules and human receptors

Human gut is in permanent contact with microorganisms that play an important role in many physiological processes including metabolism and immunologic activity. These microorganisms communicate and manage themself by the quorum sensing system (QS) that helps to coordinate optimal growth and subsistence by activating signaling pathways that regulate bacterial gene expression. Diverse QS molecules produced by pathogenic as well as resident microbiota have been found throughout the human gut. However, even a host can by affected by these molecules. Intestinal and immune cells possess a range of molecular targets for QS. Our present knowledge on bacteria-cell communication encompasses G-protein-coupled receptors, nuclear receptors and receptors for bacterial cell-wall components. The QS of commensal bacteria has been approved as a protective factor with favourable effects on intestinal homeostasis and immunity. Signaling molecules of QS interacting with above-mentioned receptors thus parcipitate on maintaining of barrier functions, control of inflammation processes and increase of resistance to pathogen colonization in host organisms. Pathogens QS molecules can have a dual function. Host cells are able to detect the ongoing infection by monitoring the presence and changes in concentrations of QS molecules. Such information can help to set the most effective immune defence to prevent or overcome the infection. Contrary, pathogens QS signals can target the host receptors to deceive the immune system to get the best conditions for growth. However, our knowledge about communication mediated by QS is still limited and detailed understanding of molecular mechanisms of QS signaling is desired.

Bioisosteric replacements of the indole moiety for the development of a potent and selective PI3Kδ inhibitor: Design, synthesis and biological evaluation

Based on indole scaffold, a potent and selective phosphoinositide 3-kinase delta (PI3Kδ) inhibitor, namely FD223, was developed by the bioisosteric replacement drug discovery approach and studied for the treatment of acute myeloid leukemia (AML). In vitro studies revealed that FD223 displays high potency (IC₅₀ = 1 nM) and selectivity (29-51 fold over other PI3K isoforms) against PI3Kδ, and exhibits efficient inhibition of the proliferation of AML cell lines (MOLM-16, HL-60, EOL-1 and KG-1) by suppressing p-AKT Ser473 thus causing G1 phase arrest during the cell cycle. Further given the favorable pharmacokinetic (PK) profiles of FD223, in vivo studies were evaluated using xenograft model in nude mice, confirming its significant antitumor efficacy meanwhile with no observable toxicity. All these results are comparable to the positive group of Idelalisib (CAL-101), indicating that FD223 has potential for further development as a promising PI3Kδ inhibitor for the treatment of leukemia such as AML.

Anticancer properties of indole derivatives as IsoCombretastatin A-4 analogues

In this study, a variety of original ligands related to Combretastatin A-4 and isoCombretastatin A-4, able to inhibit the tubulin polymerization into microtubules, was designed, synthesized, and evaluated. Our lead compound 15d having a quinazoline as A-ring and a 2-substituted indole as B-ring separated by a N-methyl linker displayed a remarkable sub-nanomolar level of cytotoxicity (IC₅₀ < 1 nM) against 9 human cancer cell lines.

l-Hypaphorine and d-hypaphorine: Specific antiacetylcholinesterase activity in rat brain tissue

Acetylcholinesterase (AChEis) inhibitors are used to treat neurodegenerative diseases like Alzheimer's disease (AD). l-Hypaphorine (l-HYP) is a natural indole alkaloid that has been shown to have effects on the central nervous system (CNS). The goal of this research was to synthesize l-HYP and d-HYP and test their anticholinesterasic properties in rat brain regions. l-HYP suppressed acetylcholinesterase (AChE) activity only in the cerebellum, whereas d-HYP inhibited AChE activity in all CNS regions studied. No cytotoxic effect on normal human cells (HaCaT) was observed in the case of l-HYP and d-HYP although an increase in cell proliferation. Molecular modeling studies revealed that d-HYP and l-HYP have significant differences in their binding mode positions and interact stereospecifically with AChE's amino acid residues.

Identification of 3-Bromo-1-Ethyl-1H-Indole as a Potent Anticancer Agent with Promising Inhibitory Effects on GST Isozymes

BACKGROUND

Indole-based heterocyclic compounds play important roles in pharmaceutical chemistry due to their unexpected biological and pharmacological properties.

OBJECTIVE

Herein, we describe novel biological properties (antioxidant, antimicrobial and anti-cancer) of 3- bromo-1-ethyl-1H-indole (BEI) structure.

METHODS

BEI was synthesized from 1-Methyl-2-phenylindole and N-bromosuccinimide and was characterized by using 1H and 13C NMR. Cytotoxicity was determined by MTT assay. Apoptosis analysis of BEI was determined by Arthur™ image-based Cytometer. Different methods were applied to assess the antioxidant activity of BEI. Molecular docking studies were conducted to determine the interactions of bonding between GST isozymes and BEI.

RESULTS

According to the antioxidant and antimicrobial activity assays, BEI compound showed reduced total antioxidant activity compared to the Trolox standard, whereas it showed moderate antimicrobial activity against Aspergillus niger and Phytophora eryhtrospora. Notably, the BEI compound demonstrated substantial selective cytotoxicity for the first time towards cancer cell lines, and there existed a significant decrease in the percentage of live cells treated with BEI, in comparison to the control ones. Interestingly, BEI exhibited a promising glutathione S-transferase isozymes inhibition.

CONCLUSION

The results of this study suggest that BEI seems to be a promising molecule to be used in the design of new anti-cancer agents that provide superiority to present commercial anti-cancer drugs.

Discovery of an indole-substituted furanone with tubulin polymerization inhibition activity

Analogs of diarylpyrrolinone lead compound 1 were prepared and tested for anti-proliferative activity in U-937 cancer cells. Alterations of 1 focused on modifying the two nitrogen atoms: a) the pyrrolinone nitrogen atom was substituted with a propyl group or replaced with an oxygen atom (furanone), and b) the substituents on the indole nitrogen were varied. These changes led to the discovery of a furanone analog 3b with sub-micromolar anti-cancer potency and tubulin polymerization inhibition activity.

Rationally designed TNF-α inhibitors: Identification of promising cytotoxic agents

Design and synthesis of new indole derivatives as tumor growth inhibiting agents via inhibiting the TNF-α is described. The preliminary results showed the inhibition of LPS induced production of NO, TNF-α and IL-6 by these compounds out of which compounds 2d and 2g exhibited appreciable cytotoxicity against the 60 cell lines panel of human cancer. The rationale behind the design of the molecules and the results of their biological studies are presented. 2009 Elsevier Ltd. All rights reserved.