Design, synthesis, in vitro, and in silico anti-α-glucosidase assays of N-phenylacetamide-1,2,3-triazole-indole-2-carboxamide derivatives as new anti-diabetic agents.

In this work, a novel series of N-phenylacetamide-1,2,3-triazole-indole-2-carboxamide derivatives 5a-n were designed by consideration of the potent α-glucosidase inhibitors containing indole and carboxamide-1,2,3-triazole-N-phenylacetamide moieties. These compounds were synthesized by click reaction and evaluated against yeast α-glucosidase. All the newly title compounds demonstrated superior potency when compared with acarbose as a standard inhibitor. Particularly, compound 5k possessed the best inhibitory activity against α-glucosidase with around a 28-fold improvement in the inhibition effect in comparison standard inhibitor. This compound showed a competitive type of inhibition in the kinetics. The molecular docking and dynamics demonstrated that compound 5k with a favorable binding energy well occupied the active site of α-glucosidase.

Modular Synthesis and Antimicrobial Investigation of Mycoleptodiscin A and Simplified Indolosesquiterpenoids.

The structure-activity relationship of the unusual indolosesquiterpenoid mycoleptodiscin A is unknown due to natural scarcity and inefficient synthesis. A modular approach leveraging Larock indole synthesis has been established to access mycoleptodiscin A and a divergent collection of drimenyl indoles. It features the utilization of an inexpensive (+)-sclareolide, modularity, purification-economy, and scalability, which facilitates the first biological evaluation of mycoleptodiscin A and related precursors.

Promising anti-proliferative indolic benzenesulfonamides alter mechanisms with sulfonamide nitrogen substituents.

Agents that cause apoptotic cell death by interfering with tubulin dynamics, such as vinblastine and paclitaxel, are an important class of chemotherapeutics. Unfortunately, these compounds are substrates for multidrug resistance (MDR) pumps, allowing cancer cells to gain resistance to these chemotherapeutics. The indolesulfonamide family of tubulin inhibitors are not excluded by MDR pumps and have a promising activity profile, although their high lipophilicity is a pharmacokinetic limitation for their clinical use. Here we present a new family of N-indolyl-3,4,5-trimethoxybenzenesulfonamide derivatives with modifications on the indole system at positions 1 and 3 and on the sulfonamide nitrogen. We synthesized and screened against HeLa cells 34 novel indolic benzenesulfonamides. The most potent derivatives (1.7-109 nM) were tested against a broad panel of cancer cell lines, which revealed that substituted benzenesulfonamides analogs had highest potency. Importantly, these compounds were only moderately toxic to non-tumorigenic cells, suggesting the presence of a therapeutic index. Consistent with known clinical anti-tubulin agents, these compounds arrested the cell cycle at G2/M phase. Mechanistically, they induced apoptosis via caspase 3/7 activation, which occurred during M arrest. The substituents on the sulfonamide nitrogen appeared to determine different mechanistic results and cell fates. These results suggest that the compounds act differently depending on the bridge substituents, thus making them very interesting as mechanistic probes as well as potential drugs for further development.

Synthesis of Bisindole Alkaloids and Their Mode of Action against Methicillin-Resistant Staphylococcus Aureus.

About 100,000 deaths are attributed annually to infections with methicillin-resistant Staphylococcus aureus (MRSA) despite concerted efforts toward vaccine development and clinical trials involving several preclinically efficacious drug candidates. This necessitates the development of alternative therapeutic options against this drug-resistant bacterial pathogen. Using the Masuda borylation-Suzuki coupling (MBSC) sequence, we previously synthesized and modified naturally occurring bisindole alkaloids, alocasin A, hyrtinadine A and scalaradine A, resulting in derivatives showing potent in vitro and in vivo antibacterial efficacy. Here, we report on a modified one-pot MBSC protocol for the synthesis of previously reported and several undescribed N-tosyl-protected bisindoles with anti-MRSA activities and moderate cytotoxicity against human monocytic and kidney cell lines. In continuation of the mode of action investigation of the previously synthesized membrane-permeabilizing hit compounds, mechanistic studies reveal that bisindoles impact the cytoplasmic membrane of Gram-positive bacteria by promiscuously interacting with lipid II and membrane phospholipids while rapidly dissipating membrane potential. The bactericidal and lipid II-interacting lead compounds 5c and 5f might be interesting starting points for drug development in the fight against MRSA.

Design, synthesis and biological evaluation of indoline-maleimide conjugates as potential antitumor agents for the treatment of colorectal cancer.

An efficient protocol for direct coupling of maleimides and indolines at the C7-position was achieved under Rh(III) catalysis. Thirty four novel indoline-maleimide conjugates were prepared in good to excellent yields using this method. All compounds were evaluated for their anti-proliferative effect against colorectal cell lines. Among them, compound 3ab showed the most potent anti-proliferative activity against the CRC cells, and displayed low toxicity in the normal cell. Further investigation indicated that 3ab could effectively suppress the proliferation and migration of CRC cells, along with inducing cell cycle arrest and apoptosis. Mechanistic studies revealed that compound 3ab inhibited the proliferation of CRC cells via suppressing the AKT/GSK-3ß pathway. In vivo evaluation demonstrated remarkable antitumor effect of 3ab (10 mg/kg) in the HCT116 xenograft model with no obvious toxicity, which is superior to that of 5-Fluorouracil (20 mg/kg). Therefore, conjugate 3ab could be considered as a potential CRC therapy agent for further development.

Efficient synthesis of indole-chalcones based glycohybrids and their anticancer activity.

Indole based glycosides belong to the class of pharmacologically active molecules and found in diverse natural compounds. Herein, we report the synthesis of 1,2,3-triazole bridged chirally enriched diverse indole-chalcones based glycohybrids. Three series of glycohybrids were designed and efficiently synthesized using d-glucose, d-galactose and d-mannose derived 1-azido glycosides. The reactions sequence involved were, the synthesis of indole derived chalcones which were formed via Claisen-Schmidt condensation reaction and subsequently N-propargylation which leads to the production of N-propargylated indole-chalcones. The N-propargylated indole-chalcones get transformed into 1,2,3-triazole bridged indole-chalcone based glycohybrids by reacting with 1-azido sugar glycosides under click-chemistry reaction conditions. Further, the biological activity of synthesized glycohybrids (n = 27) was assessed in-vitro against MDA-MB231, MCF-7, MDA-MB453 cancer, and MCF-10A normal cell lines. The selected compounds showed potent anti-oncogenic properties against MCF-7 and MDA-MB231 breast cancer cell line with IC50 values of 1.05 µM and 11.40 µM respectively, with very good selectivity index (SI > 161). The active compounds show better binding affinity as compared to co-crystallized inhibitor 1-(tert-butyl)-3-(p-tolyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine (PP1) with HCK (PTKs) proteins in molecular docking studies.

Rutaecarpine-inspired scaffold-hopping strategy and Ullmann cross-coupling based synthetic approach: Identification of pyridopyrimidinone-indole based novel anticancer chemotypes.

Natural products as starting templates have shown historically major contribution to development of drugs. Inspired by the structure-function of an anticancer natural alkaloid Rutaecarpine, the Scaffold-hopped Acyclic Analogues of Rutaecarpine (SAAR) with 'N'-atom switch (1°-hop) and ring-opening (2°-hop) were investigated. A new synthetic route was developed for an effective access to the analogues, i.e. 2-indolyl-pyrido[1,2-a]pyrimidinones, which involved preparation of N-Boc-N'-phthaloyltryptamine/mexamine-bromides and pyridopyrmidinon-2-yl triflate, a nickel/palladium-catalysed Ullmann cross-coupling of these bromides and triflate, deprotection of phthalimide followed by N-aroylation, and Boc-deprotection. Fourteen novel SAAR-compounds were prepared, and they showed characteristic antiproliferative activity against various cancer cells. Three most active compounds (11a, 11b, and 11c) exhibited good antiproliferative activity, IC50 7.7-15.8 µM against human breast adenocarcinoma cells (MCF-7), lung cancer cells (A549), and colon cancer cells (HCT-116). The antiproliferative property was also observed in the colony formation assay. The SAAR compound 11b was found to have superior potency than original natural product Rutaecarpine and an anticancer drug 5-FU in antiproliferative activities with relatively lower cytotoxicity towards normal breast epithelial cells (MCF10A) and significantly higher inhibitory effect on cancer cells' migration. The compound 11b was found to possess favourable in silico physicochemical characteristics (lipophilicity-MLOGP, TPSA, and water solubility-ESOL, and others), bioavailability score, and pharmacokinetic properties (GI absorption, BBB non-permeant, P-gp, and CYP2D6). Interestingly, the compound 11b did not show any medicinal chemistry structural alert of PAINS and Brenk filter. The study represents for the first time the successful discovery of new potent anticancer chemotypes using Rutaecarpine natural alkaloid as starting template and reaffirms the significance of natural product-inspired scaffold-hopping technique in drug discovery research.

Identification of 3-(9H-carbazol-9-yl)-2-(1,3-dioxoisoindolin-2-yl)propanoic acids as promising DNMT1 inhibitors.

DNA methyltransferase 1 (DNMT1) is the primary enzyme responsible for maintaining DNA methylation patterns during cellular division, crucial for cancer development by suppressing tumor suppressor genes. In this study, we retained the phthalimide structure of N-phthaloyl-l-tryptophan (RG108) and substituted its indole ring with nitrogen-containing aromatic rings of varying sizes. We synthesized 3-(9H-carbazol-9-yl)-2-(1,3-dioxoisoindolin-2-yl)propanoic acids and confirmed them as DNMT1 inhibitors through protein affinity testing, radiometric method using tritium labeled SAM, and MTT assay. Preliminary structure-activity relationship analysis revealed that introducing substituents on the carbazole ring could enhance inhibitory activity, with S-configuration isomers showing greater activity than R-configuration ones. Notably, S-3-(3,6-di-tert-butyl-9H-carbazol-9-yl)-2-(1,3-dioxoisoindolin-2-yl)propanoic acid (7r-S) and S-3-(1,3,6-trichloro-9H-carbazol-9-yl)-2-(1,3-dioxoisoindolin-2-yl)propanoic acid (7t-S) exhibited significant DNMT1 enzyme inhibition activity, with IC50 values of 8.147 µM and 0.777 µM, respectively (compared to RG108 with an IC50 above 250 µM). Moreover, they demonstrated potential anti-proliferative activity on various tumor cell lines including A2780, HeLa, K562, and SiHa. Transcriptome analysis and KEGG pathway enrichment of K562 cells treated with 7r-S and 7t-S identified differentially expressed genes (DEGs) related to apoptosis and cell cycle pathways. Flow cytometry assays further indicated that 7r-S and 7t-S induce apoptosis in K562 cells and arrest them in the G0/G1 phase in a concentration-dependent manner. Molecular docking revealed that 7t-S may bind to the methyl donor S-adenosyl-l-methionine (SAM) site in DNMT1 with an orientation opposite to RG108, suggesting potential for deeper penetration into the DNMT1 pocket and laying the groundwork for further modifications.

Development of Potent Microtubule Targeting Agent by Structural Simplification of Natural Diazonamide.

The marine metabolite diazonamide A exerts low nanomolar cytotoxicity against a range of tumor cell lines; however, its highly complex molecular architecture undermines the therapeutic potential of the natural product. We demonstrate that truncation of heteroaromatic macrocycle in natural diazonamide A, combined with the replacement of the challenging-to-synthesize tetracyclic hemiaminal subunit by oxindole moiety leads to considerably less complex analogues with improved drug-like properties and nanomolar antiproliferative potency. The structurally simplified macrocycles are accessible in 12 steps from readily available indolin-2-one and tert-leucine with excellent diastereoselectivity (99:1 dr) in the key macrocyclization step. The most potent macrocycle acts as a tubulin assembly inhibitor and exerts similar effects on A2058 cell cycle progression and induction of apoptosis as does marketed microtubule-targeting agent vinorelbine.

Synthesis, characterization, DNA interaction, molecular docking, and α-amylase and α-glucosidase inhibition studies of a water soluble Zn(II) phthalocyanine.

In this study, 2(3),9(10),16(17),23(24)-tetrakis-[(N-methyl-(1-benzylpiperidin-4-yl)oxy)phthalocyaninato]zinc(II) iodide (ZnPc-2) was synthesized and characterized using spectral methods (FT-IR, 1H-NMR, UV-Vis and mass spectroscopy). The interaction of ZnPc-2 with DNA was investigated by using the UV/Vis titrimetric method, thermal denaturation profile, agarose gel electrophoresis and molecular docking studies. Additionally, the antidiabetic activity of ZnPc-2 was revealed spectroscopically by studying α-amylase and α-glucosidase inhibition activities. The spectroscopic results indicated that ZnPc-2 effectively binds to calf thymus-DNA (CT-DNA) with a Kb value of 7.5 × 104 M-1 and interacts with CT-DNA via noncovalent binding mode. Gel electrophoresis results also show that ZnPc-2 binds strongly to DNA molecules and exhibits effective nuclease activity even at low concentrations. Furthermore, docking studies suggest that ZnPc-2 exhibits a stronger binding tendency with DNA than the control compounds ethidium bromide and cisplatin. Consequently, due to its strong DNA binding and nuclease activity, ZnPc-2 may be suitable for antimicrobial and anticancer applications after further toxicological tests. Additionally, antidiabetic studies showed that ZnPc-2 had both α-amylase and α-glucosidase inhibition activity. Moreover, the α-glucosidase inhibitory effect of ZnPc-2 was approximately 3500 times higher than that of the standard inhibitor, acarbose. Considering these results, it can be said that ZnPc-2 is a moderate α-amylase and a highly effective α-glucosidase inhibitor. This suggests that ZnPc-2 may have the potential to be used as a therapeutic agent for the treatment of type 2 diabetes.

Synthesis, characterization and biological applications of substituted indolo[2,1-b]quinazolin-12(6H)-one based rhenium(I) organometallic compounds.

The Re(I) organometallic compounds [(Re(CO)3L1-6 )Cl], where Ligand(L) = Tryptanthrin derivatives were prepared and characterized by various spectroscopic techniques. To assess the binding capacities and binding manner, tests of Calf thymus DNA under the impact of organometallic complexes were conducted using absorption titration and viscosity measuring techniques. Data from the research mentioned above point to an intercalation type of binding, which was verified by the docking study. Swiss ADME tools carried out an ADME study. The work focuses on computing the molecular orbital energies for the synthesized compounds using the density functional theory (DFT). The compounds were tested against the MCF-7 cell line to determine their anticancer effects. It was observed that their IC50 values were equivalent to those of the standard medication, indicating that they had a similar antiproliferative impact.

Bisindole-based small molecules as transmembrane anion transporters and potential anticancer agents.

Few synthetic ion transporters have been reported incorporating indole as the core moiety. We have developed a novel bisindole-based transporter capable of efficient transmembrane anion antiport. This system induced cytotoxicity in MCF-7 breast cancer cells via chloride ion homeostasis disruption and the associated ROS generation, mitochondrial membrane depolarization, and lysosomal deacidification.

Borylation via iridium catalysed C-H activation: a new concise route to duocarmycin derivatives.

The synthesis of the ethyl ester analogue of the ultrapotent antitumour antibiotic seco-duocarmycin SA has been achieved in eleven linear steps from commercially available starting materials. The DSA alkylation subunit can be made in ten linear steps from the same precursor. The route involves C-H activation at the equivalent of the C7 position on indole leading to a borylated intermediate 9 that is stable enough for peptide coupling reactions but can be easily converted to the free hydroxyl analogue.

Exploration of 1-(indolin-1-yl)-2-(thiazol-2-yl)ethan-1-one derivatives as novel anti-HBV agent with potential TLR7-agonistic effect.

Hepatitis B virus (HBV) infection, as a serious global public health issue, is closely related to the immune dysfunction. Herein, thirty-seven 1-(indolin-1-yl)-2-(thiazol-4-yl)ethan-1-one derivatives were prepared as potential immunomodulatory anti-HBV agents. Anti-HBV activity evaluation confirmed compound 11a could significantly suppress the HBV DNA replication in both wild and resistant HBV stains, with IC50 values of 0.13 µM and 0.36 µM, respectively. Preliminary action mechanism studies showed that 11a had an inhibitory effect on cellular HBsAg secretion and could effectively activate TLR7, thereby inducing the secretion of TLR7-regulated cytokines IL-12, TNF-α and IFN-α in human PBMC cells. SPR analysis confirmed that 11a could bind to TLR7 protein with an affinity of 7.06 µM. MD simulation predicted that 11a could form tight interactions with residues in the binding pocket of TLR7. Physicochemical parameters perdition and pharmacokinetic analysis indicated that 11a displayed relatively favorable drug-like properties. Considering all the results, compound 11a might be a promising lead for developing novel immunomodulatory anti-HBV agents.

Design, synthesis, and biological evaluation of 2-(2-oxoindolin-3-ylidene)hydrazinecarbothioamides as a potential EGR-1 inhibitor for targeted therapy of atopic dermatitis.

Atopic dermatitis is a chronic inflammatory skin disease characterized by intense itching and frequent skin barrier dysfunctions. EGR-1 is a transcription factor that aggravates the pathogenesis of atopic dermatitis by promoting the production of various inflammatory cytokines. Three 2-(2-oxoindolin-3-ylidene)hydrazinecarbothioamides (IT21, IT23, and IT25) were identified as novel inhibitors of EGR-1 DNA-binding activity. In silico docking experiments were performed to elucidate the binding conditions of the EGR-1 zinc-finger (ZnF) DNA-binding domain. Electrophoretic mobility shift assays confirmed the targeted binding effect on the EGR-1 ZnF DNA-binding domain, leading to dose-dependent dissociation of the EGR-1-DNA complex. At the functional cellular level, IT21, IT23, and IT25 effectively reduced mRNA expression of TNFα-induced EGR-1-regulated inflammatory genes, particularly in HaCaT keratinocytes inflamed by TNFα. In the in vivo efficacy study, IT21, IT23, and IT25 demonstrated the potential to alleviate atopic dermatitis-like skin lesions in the ear skin of BALB/c mice. These findings suggest that targeting the EGR-1 ZnF DNA-binding domain with 2-(2-oxoindolin-3-ylidene)hydrazinecarbothioamide derivatives (IT21, IT23, and IT25) could serve as lead compounds for the development of potential therapeutic agents against inflammatory skin disorders, including atopic dermatitis.

Electrochemical Synthesis of Phosphorylated Indoles and Trp-Containing Oligopeptides.

Cp2Fe-mediated electrochemical synthesis of phosphorylated indoles and Trp-containing oligopeptides has been developed, which eliminates the need for external oxidants and yields the desired products in moderate to excellent yields under mild conditions. Importantly, the synthetic applicability was further demonstrated through its easy scalability and the anticancer activity of the product. Remarkably, it presents the first electrochemical protocol to access the phosphorylation of indoles and Trp-containing oligopeptides.

Short Total Synthesis of (+)-Colletotryptins B-D and Mucronatin B Derivative.

The short and first total synthesis of (+)-colletotryptins B-D, ent-colletotryptin A, and diastereomer of mucronatin B, which are a group of natural 3-(indol-2-yl)-3-(indol-3-yl)-1,2-propanediol (IIPDO) analogues containing two stereogenic centers at the C8' and C9' positions, isolated from endophytic fungus Colletotrichum sp. SC1355 and Tetrapterys mucronata, respectively, has been successfully accomplished in two and three steps with overall yields ranging from 28 to 54%. Key features of this synthesis include an innovative Bi(OTf)3-catalyzed stereoselective transindolylation of (S)-3,3'-di(1H-indol-3-yl)propane-1,2-diol. The operational simplicity, environmentally friendly catalyst, and broad functional group tolerance of this modular strategy render it suitable for adoption in both academic and industrial settings.

Indole as a Versatile Building Block in Cycloaddition Reactions: Synthesis of Diverse Heterocyclic Frameworks.

Indole, a ubiquitous and structurally versatile aromatic compound, has emerged as a key player in the synthesis of diverse heterocyclic frameworks via cycloaddition reactions. These reactions are completely atom-economical and, hence, are considered as green reactions. This review article provides a comprehensive overview of the pivotal role played by indole in the construction of complex and biologically relevant heterocyclic compounds. Here we explore the chemistry of indole-based cycloadditions, highlighting their synthetic utility in accessing a wide array of heterocyclic architectures, including cyclohepta[b]indoles, tetrahydrocarbazoles, tetrahydroindolo[3,2-c]quinoline, and indolines, among others. Additionally, we discuss the mechanistic insights that underpin these transformations, emphasizing the strategic importance of indole as a building block. The content of this article will certainly encourage the readers to explore more work in this area.

Discovery of meisoindigo derivatives as noncovalent and orally available Mpro inhibitors: their therapeutic implications in the treatment of COVID-19.

The progressive emergence of SARS-CoV-2 variants has necessitated the urgent exploration of novel therapeutic strategies to combat the COVID-19 pandemic. The SARS-CoV-2 main protease (Mpro) represents an evolutionarily conserved therapeutic target for drug discovery. This study highlights the discovery of meisoindigo (Mei), derived from the traditional Chinese medicine (TCM) Indigo naturalis, as a novel non-covalent and nonpeptidic Mpro inhibitor. Substantial optimizations and structure-activity relationship (SAR) studies, guided by a structure-based drug design approach, led to the identification of several Mei derivatives, including S5-27 and S5-28, exhibiting low micromolar inhibition against SARS-CoV-2 Mpro with high binding affinity. Notably, S5-28 provided significant protection against wild-type SARS-CoV-2 in HeLa-hACE2 cells, with EC50 up to 2.66 µM. Furthermore, it displayed favorable physiochemical properties and remarkable gastrointestinal and metabolic stability, demonstrating its potential as an orally bioavailable drug for anti-COVID-19 therapy. This research presents a promising avenue for the development of new antiviral agents, offering hope in the ongoing battle against COVID-19.

Design, Synthesis, and Antibacterial Evaluation of Novel Isoindolin-1-ones Derivatives Containing Piperidine Fragments.

A series of novel isoindoline-1-one derivatives containing piperidine moiety were designed and synthesized using natural compounds as raw materials, and their biological activities were tested for three bacterial and three fungal pathogens. These derivatives exhibited good against phytopathogenic bacteria activities against Pseudomonas syringae pv actinidiae (Psa) and Xanthomonas axonopodis pv.citri (Xac). Some compounds exhibited excellent antibacterial activities against Xanthomonas oryzae pv oryzae (Xoo). The dose of Y8 against Xoo (the maximum half lethal effective concentration (EC50) = 21.3 µg/mL) was better than that of the thiediazole copper dose (EC50 = 53.3 µg/mL). Excitingly, further studies have shown that the molecular docking of Y8 with 2FBW indicates that it can fully locate the interior of the binding pocket through hydrogen bonding and hydrophobic interactions, thereby enhancing its anti-Xoo activity. Scanning electron microscopy (SEM) studies revealed that Y8 induced the Xoo cell membrane collapse. Moreover, the proteomic results also indicate that Y8 may be a multifunctional candidate as it affects the formation of bacterial Xoo biofilms, thereby exerting antibacterial effects.