Syntheses of 3-(2-Nitrovinyl)-indoles, Benzo[a]carbazoles, Naphtho[2,1-a]carbazoles, and 1-Hydroxy-ß-carbolines Lead to Identification of Antiproliferative Compounds Active under Hypoxia.

Herein, we describe a novel reaction between C-2-substituted indoles and 2-nitroacetophenones leading to a variety of indole-containing heterocyclic scaffolds. At 60 °C in AcOH with H2SO4 as catalyst, C-2 aryl indoles give 3-(2-nitrovinyl)-indoles with high Z or E geometric selectivity depending on the type of substrate utilized. These compounds undergo an electrocyclization process in a sealed vial in a microwave apparatus in DMF at 250 °C to give benzo[a]carbazoles and naphtho[2,1-a]carbazoles depending on whether the C-2 aromatic moiety is phenyl or naphthyl. Utilization of 2-methylindoles in the reaction with 2-nitroacetophenones and performing the reaction in a sealed vial in a microwave apparatus in AcOH at 200 °C leads to 1-hydroxy-ß-carbolines. Selected compounds from each scaffold were tested for antiproliferative activities against MDA-MB-231 triple-negative breast cancer cells under normoxic and hypoxic conditions, and three compounds belonging to the 3-(2-nitrovinyl)-indole and 1-hydroxy-ß-carboline series were identified to have single-digit micromolar IC50 values.

Design, synthesis and biological evaluation of multitarget hybrid molecules containing NHC-Au(I) complexes and carbazole moieties.

N-heterocyclic carbenes (NHCs) represent suitable ligands for rapid and efficient drug design, because they offer the advantage of being easily chemically modified and can bind several substituents, including transition metals as, for instance, gold derivatives. Gold-NHC complexes possess various biological activities and were demonstrated good candidates as anticancer drugs. Besides, carbazole derivatives are characterized by various pharmacological properties, such as anticancer, antibacterial, anti-inflammatory, and anti-psychotropic. Amongst the latter, N-thioalkyl carbazoles were proved to inhibit cancer cells damaging the nuclear DNA, through the inhibition of human topoisomerases. Herein, we report the design, synthesis and biological evaluation of nine new hybrid molecules in which NHC-Au(I) complexes and N-alkylthiolated carbazoles are linked together, in order to obtain novel biological multitarget agents. We demonstrated that the lead hybrid complexes possess anticancer, anti-inflammatory and antioxidant properties, with a high potential as useful tools for treating distinct aspects of several diseases, amongst them cancer.

Synthesis and biological evaluation of novel 3,6- amide and thioamide substituted- 2,3,4,9-tetrahydro-1H-carbazoles for anti-cancer activity.

Herein, we report the synthesis of new compounds with demonstrated anticancer properties based on the 2,3,4,9-tetrahydro-1H-carbazole scaffold. The Fischer indolization method was used to close the heterocyclic motif. The synthesis method's scope and limitations were thoroughly assessed through a series of experiments. Biological assays revealed that two thioamide compounds exhibited significant anticancer activity against MCF-7, HTC116, and A596 cell lines. Comprehensive in vitro profiling included evaluation of cell cytotoxicity, morphological alterations, colony formation and cell adhesion in 3D cultures, cell cycle analysis, DNA damage induction, impact on mitochondria, and apoptosis. Ex ovo studies further demonstrated these compounds' potential to inhibit angiogenic processes. Our results indicate that the newly developed compounds activate processes leading to DNA damage and disruption of mitochondrial function.

Novel carbazole-oxadiazole derivatives as anti-α-glucosidase and anti-α-amylase agents: Design, synthesis, molecular docking, and biological evaluation.

To find novel inhibitors of α-glucosidase and α-amylase, a series of new carbazole-oxadiazole derivatives (6a-6n) were prepared, and screened for their anti-α-glucosidase and anti-α-amylase effects. Most of the tested derivatives showed different degrees of α-glucosidase and α-amylase inhibitory activity (IC50: 21.39 ± 0.69-92.05 ± 1.54 µM, 45.53 ± 1.50-126.14 ± 6.33 µM, respectively) compared to the standard acarbose (IC50: 427.00 ± 9.56 µM, 24.68 ± 1.10 µM, respectively). Thereinto, 6c (IC50 = 21.39 ± 0.69 µM) displayed the most effective anti-α-glucosidase activity and 6e presented the best anti-α-amylase activity with an IC50 value of 45.53 ± 1.50 µM. Lineweaver-Burk plot analysis suggested that 6c and 6e behaved as mixed α-glucosidase inhibitor and mixed α-amylase inhibitor, respectively. The results of circular dichroism, atomic force microscope, and molecular docking simulation exposed interaction mechanisms between two preferred compounds (6c and 6e) and their corresponding enzymes. Combined with the possible properties of reducing the elevation in postprandial blood glucose, oral activity, positive bioavailability, and low cytotoxicity of 6c and 6e, it could be concluded that the target derivatives may be able to act as lead molecules for the development of new hypoglycemic agents.

Synthesis of biscarbazole derivative, detection of the "on-off" sensor property of Cu2+ by fluorimetry, and anti-cancer evaluation.

Biscarbazole derivative probe (6) (Z)-2-(3-(((9-heptyl-9H-carbazol-3-yl)methylene)amino)-9H-carbazol-9-yl)ethan-1-ol containing an imine group, which is a sensitive and selective fluorescence chemosensor, was designed and synthesized for the effective evaluation of Cu2+ metal ion levels. The synthesized compounds were characterized using 1H NMR, 13C NMR, FT-IR, and MALDI-TOF MS (for compound 6) spectroscopic data. The interaction model between probe 6 and Cu2+ was determined by combining fluorescence methods, 1H NMR titration, Job's plot, and theoretical calculations. For probe 6, the fluorogenic recognition of Cu2+ was investigated by fluorescence spectroscopy, and the optical changes caused by Cu2+ ions were carried out in ACN/H2O (50:50) solution at pH 7.0. Fluorescence probe 6 was found to "turn-off" its fluorescence in the presence of paramagnetic Cu2+ ions. Probe 6 was determined to have a rapid response within 40s and showed a fluorescence response to Cu2+ with a low detection limit of 0.16 µM. Additionally, in vitro anticancer activity and cell imaging studies of probe 6 against the prostate cell line (PC-3) were performed.

A water-soluble luminescent tris(2,4,6-trichlorophenyl)methyl radical-carbazole dyad.

Organic luminescent radicals are a new class of materials with potential applications not only in light-emitting devices but also in the biochemistry field. New tris(2,4,6-trichlorophenyl)methyl (TTM) radicals with alkoxy-substituted carbazole donors were synthesized and characterized. PEG-substituted carbazole-TTM was found to be water-soluble. The water-soluble TTM radical aqueous solution showed fluorescence at 777 nm and the ability to shorten the longitudinal relaxation time (T1) of water. The concept of water-soluble luminescent radicals is expected to be used to develop a potential fluorescence and MR dual-use imaging moiety.

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.

Structure-activity relationship study of new carbazole sulfonamide derivatives as anticancer agents with dual-target mechanism.

A series of novel carbazole sulfonamide derivatives were synthesized and evaluated for antiproliferative activity. Among them, compounds 7 and 15 showed strong potency (IC50 values of 0.81-31.19 nM) against five different cancer cells including multidrug-resistant MCF7/ADR cells. Compound 15 displayed a high cancer cell selectivity (IC50(L02)/average IC50: SI = 7.7). The l-valine prodrug 7a and the phosphate prodrug 15a exerted rohust in vivo antitumor efficacies and accepted safety prolifes. Further mechanism studies revealed that 7 and 15 directly bind to the colchicine site in tubulin to block tubulin polymerization, promote microtubule fragmentation at the cellular level, and induce apoptosis with G2/M cell cycle arrest. These compounds also inhibit HEMC-1 cells migration and vascular tube formation. Additionally, compound 7 displayed a selective inhibition of Topo I. Collectively, these studies suggest that 7 and 15 represents a promising new generation of tubulin inhibitors for cancer treatment.

Molecular Design of Naphthalene- and Carbazole-Based Monomers for Regiospecific Synthesis of Poly(arylenevinylene)s via Co-Catalyzed Hydroarylation Polyaddition.

This study focuses on the development of regiospecific hydroarylation polyaddition of naphthalene- and carbazole-based monomers with diynes under mild reaction conditions at room temperature. A 1-pyrazole substituent serves as an appropriate directing group for a Co-catalyst to efficiently activate the C-H bonds of generally inactive six-membered aromatic hydrocarbons. The 1-pyrazole groups in 2,6-di(1-pyrazolyl)naphthalene adopt planar conformations and act as directing groups, resulting in a smooth hydroarylation reaction. In contrast, the reaction with 1,5-di(1-pyrazolyl)naphthalene do not proceed. The polyaddition reaction of 2,6-di(1-pyrazolyl)naphthalene selectively proceeds at 3,7-positions under mild reaction conditions at 30 °C, and yields corresponding poly(arylenevinylene) (PAV) with high molecular weight. This molecular design is also applicable to the hydroarylation polyaddition of carbazole; the polyaddition reaction of 9-(2-ethylhexyl)-3,6-di(1-pyrazolyl)carbazole selectively occurred at 2,7-positions. The optical and electronic properties of the synthesized compounds are evaluated. The obtained PAVs serve as an emitting material in organic light-emitting diode (OLED). This study aims to develop a Co-catalyzed hydroarylation polyaddition via C-H activation of generally inactive polyaromatic hydrocarbons (PAHs) under mild conditions.

Design, Synthesis, and Pharmacological Evaluation of Spiro[carbazole-3,3'-pyrrolidine] Derivatives as cGAS Inhibitors for Treatment of Acute Lung Injury.

Overactivation of cyclic GMP-AMP synthase (cGAS) is implicated in the occurrence of many inflammatory and autoimmune diseases, and inhibition of cGAS with a specific inhibitor has been proposed as a potential therapeutic strategy. However, only a few low-potency cGAS inhibitors have been reported, and few are suitable for clinical investigation. As a continuation of our structural optimization on the reported cGAS inhibitor 6 (G140), we developed a series of spiro[carbazole-3,3'-pyrrolidine] derivatives bearing a unique 2-azaspiro[4.5]decane structural motif, among which compound 30d-S was identified with high cellular effects against cGAS. This compound showed improved plasma exposure, lower clearance, and an oral bioavailability of 35% in rats. Moreover, in the LPS-induced acute lung injury (ALI) mice model, oral administration of compound 30d-S at 30 mg/kg markedly reduced lung inflammation and alleviated histopathological changes. These results confirm that 30d-S is a new efficacious cGAS inhibitor and is worthy of further investigation.