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.

Facile synthesis of 2-hydroxy-ß-cyclodextrin/polyacrylamide/carbazole hydrogel and its application for the treatment of infected wounds in a murine model.

This work aimed to synthesize hydrogels by combining carbazole (Carb) with 2-hydroxy, ß-cyclodextrin (HPßCD)/polyacrylamide (PAA) hybrid complexes. The hydrogels were then evaluated for their potential use in treating infected wounds. The physicochemical structures of the preparations were evaluated using several characterization methods including FTIR, FESEM, EDX, XRD, pH sensitivity, and TGA. Moreover, In vitro release, toxicity, antibacterial activity and in vivo infected wound healing activity were evaluated. Physicochemical testing verified the effective synthesis of the preparations and the timely release of Carb. The P(AA-co-AM)/HPßCD material exhibited an open structure characterized by macroscopic voids, whereas the hydrogels displayed surfaces that were not uniform. The FTIR analysis revealed the creation of a novel polymeric hydrogel composed of HPßCD as the main polymer structure. The hydrogels exhibited good reversible swelling and recoverable deformation, with an optimal swelling ratio of 30.12 achieved at pH 7.4. The antibacterial and safety of the formulations were validated by in vitro studies. ß.Dex/PAA/Carb hydrogels have been shown to effectively expedite the healing of infected wounds by promoting the production of CD31, FGF-2, and COL1A, while reducing the levels of ROS, CD68, COX-2, and NF-κB. Overall, the combination of Carb, ß.Dex, and PAA molecules had a synergistic impact on the healing process of infected wounds.

Micro-/Mesoporous Fluorescent Polymers and Devices for Visual Pesticide Detection with Portability, High Sensitivity, and Ultrafast Response.

The residue of pesticides in crops, soil, and water continues to be a widespread concern due to the threat to human health and food safety. With the aim to develop highly sensitive sensing materials and portable detection devices, two dicarbazole-based fluorescent micro-/mesoporous polymers (JYs) with a larger specific surface area and pore sizes ranging from 1.1 to 34.2 nm are synthesized. The Stern-Volmer constants of JY fluorescence quenching for imidacloprid (50,063 M-1) exceed 23-51 times those of the reported porous organic polymers (980-2173 M-1). Of particular interest is the observation that JYs show rapid fluorescence response (2 s) and ultralow detection limit (30 ppb) for imidacloprid in water medium. The pronounced chemsensing property is attributed to the synergistic role of the hierarchical pore structure, large π-conjugation of chromophore groups, and strong inner filter effect between the polymer and imidacloprid molecule. Moreover, the pesticide detection of JYs exhibits good interference resistance in complicated service environments such as the extract liquids of the apple peel and field soil as well as aqueous solutions of various cations and anions. Because of the portability, excellent reusability, and sensitive fluorescence response, the prepared JYs and detection devices have promising applications in the on-site monitoring and early warning of the pesticide residues.

One- and Two-Photon Uncaging of Carbon Monoxide (CO) with Real-Time Monitoring: On-Demand Carbazole-Based Dual CO-Releasing Platform to Test over Single and Combinatorial Approaches for the Efficient Regression of Orthotopic Murine Melanoma In Vivo.

Herein, we report three new metal-free, photochemically active single, dual, and combinatorial CORMs (photoCORMs) based on a carbazole-fused 1,3-dioxol-2-one moiety which released one equivalent of CO, two equivalent of CO, and a combination of one equivalent of each CO and anticancer drug upon one- and two-photon excitation, respectively. The photoCORMs exhibited good cellular uptake and real-time monitoring ability of CO uncaging by a color change approach in cancerous B16F10 cells. Interestingly, the cytotoxicity assay on B16F10 cells indicated that the dual photoCORM has increased anticancer activity over the single and combinatorial photoCORMs upon irradiation. Our results also showed that CO could accelerate the effectiveness of the well-known anticancer drug (chlorambucil). Finally, the in vivo evaluation of the dual photoCORM on an established murine melanoma tumor (C57BL/6J mouse model) manifested a significant regression of tumor volume and led to significant improvement (>50%) in the overall survivability.

Exploring determinants of agonist efficacy at the CB1 cannabinoid receptor: Analogues of the synthetic cannabinoid receptor agonist EG-018.

Neutral antagonists of GPCRs remain relatively rare-indeed, a large majority of GPCR antagonists are actually inverse agonists. The synthetic cannabinoid receptor agonist (SCRA) EG-018 was recently reported as a low efficacy cannabinoid receptor agonist. Here we report a comparative characterization of EG-018 and 13 analogues along with extant putative neutral antagonists of CB1 . In HEK cells stably expressing human CB1 , assays for inhibition of cAMP were performed by real-time BRET biosensor (CAMYEL), G protein cycling was quantified by [35 S]GTPγS binding, and stimulation of pERK was characterized by AlphaLISA (PerkinElmer). Signaling outcomes for the EG-018 analogues were highly variable, ranging from moderate efficacy agonism with high potency, to marginal agonism at lower potency. As predicted by differing pathway sensitivities to differences in ligand efficacy, most EG-018-based compounds were completely inactive in pERK alone. The lowest efficacy analogue in cAMP assays, 157, had utility in antagonism assay paradigms. Developing neutral antagonists of the CB1 receptor has been a long-standing research goal, and such compounds would have utility both as research tools and in therapeutics. Although these results emphasize again the importance of system factors in determining signaling outcomes, some compounds characterized in this study appear among the lowest efficacy agonists described to date and therefore suggest that development of neutral antagonists is an achievable goal for CB1 .

[Development of New Synthetic Methods for Carbazole Compounds Aimed at Drug Discovery and Exploratory Research on Pharmaceutical Materials].

We are developing the synthesis of biologically interesting carbazole compounds, including natural products by tandem cyclic reactions. In this report, we describe the new synthesis of carbazole-1,4-quinones as follows; 1) the synthesis of carbazole-1,4-quinones using a tandem ring closing metathesis (RCM) -dehydrogenation reaction, 2) a novel one-pot synthesis of carbazole-1,4-quinone by consecutive Pd-catalyzed cyclocarbonylation, desilylation, and oxidation reactions. Two new synthetic strategies were applied to the synthesis of carbazole-1,4-quinone alkaloids and ellipticine quinones, and then the antiproliferative activity against HCT-116 and HL-60 cells of the synthesized compounds were evaluated.

Synthesis of Murrayaquinone-A Derivatives and Investigation of Potential Anticancer Properties.

A series of novel murrayaquinone a derivatives were synthesized and their anti-cancer activity were evaluated on healthy colon cell lines (CCD-18Co), primary (Caco-2) and metastatic (DLD-1) colon cancer cell lines. The results showed that the cytotoxicity of murrayaquinone molecules is significantly high even in micromolar levels. The DNA binding, cell cycle arrest and metabolic activity studies of these molecules were also carried out and the results showed that these molecules induce apoptosis. In conclusion, the data support further studies on murrayaquinone derivatives toward selection of a candidate for cancer treatment.

Synthesis and Bioinformatic Characterization of New Schiff Bases with Possible Applicability in Brain Disorders.

(1) Background: The research aims to find new treatments for neurodegenerative diseases, in particular, Alzheimer's disease. (2) Methods: This article presents a bioinformatics and pathology study of new Schiff bases, (EZ)-N'-benzylidene-(2RS)-2-(6-chloro-9H-carbazol-2-yl)propanehydrazide derivatives, and aims to evaluate the drug-like, pharmacokinetic, pharmacodynamic and pharmacogenomic properties, as well as to predict the binding to therapeutic targets by applying bioinformatics, cheminformatics and computational pharmacological methods. (3) Results: We obtained these Schiff bases by condensing (2RS)-2-(6-chloro-9H-carbazol-2-yl)propanehydrazide with aromatic aldehydes, using the advantages of microwave irradiation. The newly synthesized compounds were characterized spectrally, using FT-IR and NMR spectroscopy, which confirmed their structure. Using bioinformatics tools, we noticed that all new compounds are drug-likeness features and may be proposed as potentially neuropsychiatric drugs (4) Conclusions: Using bioinformatics tools, we determined that the new compound 1e had a high potential to be used as a good candidate in neurodegenerative disorders treatment.

Exploration of Benzo[b]carbazole-6,11-diones as anticancer agents: Synthesis and studies of hTopoIIα inhibition and apoptotic effects.

Two series of (hetero)arylamino-naphthoquinones and benzo-fused carbazolequinones were considered for study with the rationale that related structural motifs are present in numerous drugs, clinical trial agents, natural products and hTopoIIα inhibitors. Total 42 compounds were synthesized by reactions including dehydrogenative CN and Pd-catalyzed CC bond forming transformations. These compounds were screened against numerous cancer cells including highly metastatic one (MCF-7, MDA-MB-231, H-357 and HEK293T), and normal cells (MCF 10A). Some of the active compounds were evaluated for clonogenic cell survival and apoptotic effects in cancer cells (DAPI nuclear staining, Comet assay, Annexin-V-FITC/PI dual staining, flow cytometry, and western blot analysis with relevant proteins). All compounds were tested for hTopoIIα inhibitory activity. The investigated series compounds showed important properties like significant apoptotic antiproliferation in cancer cells with cell cycle arrest at S-phase and downregulation of NF- κß signaling cascade, relatively less cytotoxicity to normal cells, and hTopoIIα inhibition with more efficiency compared to an anticancer drug etoposide.

N,N'-bicarbazole-benzothiadiazole-based conjugated porous organic polymer for reactive oxygen species generation in live cells.

A π-conjugated porous organic polymer (BCzBz) was fabricated employing N,N'-bicarbazole and benzothiadiazole as molecular building units exhibiting broad visible light absorption. The photostable, water-dispersible, and cytocompatible BCzBz was demonstrated as an efficient probe for intracellular reactive oxygen species generation under photoirradiation.

Ionic Carbazole-Based Water-Soluble Two-Photon Photoinitiator and the Fabrication of Biocompatible 3D Hydrogel Scaffold.

Two-photon polymerization of a three-dimensional (3D) hydrogel structure has been widely applied in biological tissue engineering. For improving the biocompatibility of hydrogel structures, a new kind of ionic carbazole water-soluble photoinitiator was prepared to realize the fabrication of a 3D hydrogel structure in aqueous phase. 3,6-Bis[2-(1-methyl-pyridinium)vinyl]-9-methyl-carbazole diiodide (BMVMC) and cucurbit[7]uril (CB7) have been employed to generate a complex with better water solubility by host-guest interactions. The binding ratio of the complex was demonstrated to be 1:1 through the characterization of isothermal titration calorimetry (ITC). The two-photon absorption (TPA) cross section of the complex increases to 2500 GM compared with the 750 GM of the BMVMC molecule. Then, an aqueous-phase photoresist was obtained using the CB7/BMVMC complex as the photoinitiator and poly(ethylene glycol) diacrylate (PEGda) as the hydrogel monomer. Two-photon fabrication capability in aqueous phase has been studied using the as-prepared photoresist. A low laser threshold of 3.7 mW as well as a high resolution of 180 nm are achieved. Benefiting from the fluorescence properties of the photoinitiator, we can achieve the confocal fluorescence images without any assistance of fluorescent probes. Subsequently, a 3D engineered hydrogel scaffold microstructure was fabricated by the two-photon polymerization technology, whose biocompatibility was demonstrated by culturing the structure with living cells of L929. The BMVMC-CB7 complex and the as-prepared photoresist are demonstrated to have good biocompatibility, which is prospective for further application in tissue engineering.

Selective and effective anticancer agents: Synthesis, biological evaluation and structure-activity relationships of novel carbazole derivatives.

Carbazole alkaloids is an important class of natural products with diverse biological functions. So, the aim of this article is to explore new chemical entities containing carbazole scaffold as potential novel cytotoxic agents based on our developed three-component indole-to-carbazole reaction. Two series of carbazole derivatives were designed and synthesized, and their in vitro cytotoxic activities against three cell lines (A875, HepG2, and MARC145) were evaluated. The results indicated that some of these carbazole derivatives exhibited significantly good cytotoxic activities against tested cell lines compared with the control 5-fluorouracil (5-FU). Especially, carbazole acylhydrazone compounds 7g and 7p displayed high inhibitory activity on cancer cells, but almost no activity on normal cells. Further analysis of induced apoptosis for potential compounds indicated that the potential antitumor agents induced cell death in A875 cells at least partly (initially) by apoptosis, which might be used as promising lead scaffold for discovery of novel carbazole-type cytotoxic agents.

Semi-Synthesis of Small Molecules of Aminocarbazoles: Tumor Growth Inhibition and Potential Impact on p53.

The tumor suppressor p53 is inactivated by mutation in approximately 50% of human cancers. Small molecules that bind and stabilize those mutants may represent effective anticancer drugs. Herein, we report the tumor cell growth inhibitory activity of carbazole alkaloids and amino derivatives, as well as their potential activation of p53. Twelve aminocarbazole alkaloids were semi-synthesized from heptaphylline (1), 7-methoxy heptaphylline (2), and 7-methoxymukonal (3), isolated from Clausena harmandiana, using a reductive amination protocol. Naturally-occurring carbazoles 1-3 and their amino derivatives were evaluated for their potential effect on wild-type and mutant p53 activity using a yeast screening assay and on human tumor cell lines. Naturally-occurring carbazoles 1-3 showed the most potent growth inhibitory effects on wild-type p53-expressing cells, being heptaphylline (1) the most promising in all the investigated cell lines. However, compound 1 also showed growth inhibition against non-tumor cells. Conversely, semi-synthetic aminocarbazole 1d showed an interesting growth inhibitory activity in tumor cells expressing both wild-type and mutant p53, exhibiting low growth inhibition on non-tumor cells. The yeast assay showed a potential reactivation of mutant p53 by heptaphylline derivatives, including compound 1d. The results obtained indicate that carbazole alkaloids may represent a promising starting point to search for new mutp53-reactivating agents with promising applications in cancer therapy.

The synthesis of biologically active indolocarbazole natural products.

Covering: up to 2020The indolocarbazoles, in particular indolo[2,3-a]pyrrolo[3,4-c]carbazole derivatives, are an important class of natural products that exhibit a wide range of biological activities. There has been a plethora of synthetic approaches to this family of natural products, leading to advances in chemical methodology, as well as affording access to molecular scaffolds central to protein kinase drug discovery programmes. In this review, we compile and summarise the synthetic approaches to the indolo[2,3-a]pyrrolo[3,4-c]carbazole derivatives, spanning the period from their isolation in 1980 up to 2020. The selected natural products include indolocarbazoles not functionalised at indolic nitrogen, pyranosylated indolocarbazoles, furanosylated indolocarbazoles and disaccharideindolocarbazoles.

Enantioselective Synthesis of α-All-Carbon Quaternary Center-Containing Carbazolones via Amino-palladation/Desymmetrizing Nitrile Addition Cascade.

An enantioselective Pd(II)-catalyzed amino-cyclization and desymmetrizing nitrile addition cascade reaction of alkyne-tethered malononitriles is reported. This reaction forms two rings and one quaternary carbon center in a single step and serves as an efficient strategy for the construction of α-quaternary carbazolones with high enantioselectivities (up to 98:2 er). The utility of this method is demonstrated by product derivatization into a diverse array of heterocycles and a nitrile-containing leucomidine A analog.

Design, synthesis and evaluation of carbazole derivatives as potential antimicrobial agents.

Five series of novel carbazole derivatives containing an aminoguanidine, dihydrotriazine, thiosemicarbazide, semicarbazide or isonicotinic moiety were designed, synthesised and evaluated for their antimicrobial activities. Most of the compounds exhibited potent inhibitory activities towards different bacterial strains (including one multidrug-resistant clinical isolate) and one fungal strain with minimum inhibitory concentrations (MICs) between 0.5 and 16 µg/ml. Compounds 8f and 9d showed the most potent inhibitory activities (MICs of 0.5-2 µg/ml). Furthermore, compounds 8b, 8d, 8f, 8k, 9b and 9e with antimicrobial activities were not cytotoxic to human gastric cancer cell lines (SGC-7901 and AGS) or a normal human liver cell line (L-02). Structure-activity relationship analyses and docking studies implicated the dihydrotriazine group in increasing the antimicrobial potency and reducing the toxicity of the carbazole compounds. In vitro enzyme activity assays suggested that compound 8f binding to dihydrofolate reductase might account for the antimicrobial effect.

Carbazole isomers induce ultralong organic phosphorescence.

Commercial carbazole has been widely used to synthesize organic functional materials that have led to recent breakthroughs in ultralong organic phosphorescence1, thermally activated delayed fluorescence2,3, organic luminescent radicals4 and organic semiconductor lasers5. However, the impact of low-concentration isomeric impurities present within commercial batches on the properties of the synthesized molecules requires further analysis. Here, we have synthesized highly pure carbazole and observed that its fluorescence is blueshifted by 54 nm with respect to commercial samples and its room-temperature ultralong phosphorescence almost disappears6. We discover that such differences are due to the presence of a carbazole isomeric impurity in commercial carbazole sources, with concentrations <0.5 mol%. Ten representative carbazole derivatives synthesized from the highly pure carbazole failed to show the ultralong phosphorescence reported in the literature1,7-15. However, the phosphorescence was recovered by adding 0.1 mol% isomers, which act as charge traps. Investigating the role of the isomers may therefore provide alternative insights into the mechanisms behind ultralong organic phosphorescence1,6-18.

Crystallography-guided discovery of carbazole-based retinoic acid-related orphan receptor gamma-t (RORγt) modulators: insights into different protein behaviors with "short" and "long" inverse agonists.

A series of 6-substituted carbazole-based retinoic acid-related orphan receptor gamma-t (RORγt) modulators were discovered through 6-position modification guided by insights from the crystallographic profiles of the "short" inverse agonist 6. With the increase in the size of the 6-position substituents, the "short" inverse agonist 6 first reversed its function to agonists and then to "long" inverse agonists. The cocrystal structures of RORγt complexed with the representative "short" inverse agonist 6 (PDB: 6LOB), the agonist 7d (PDB: 6LOA) and the "long" inverse agonist 7h (PDB: 6LO9) were revealed by X-ray analysis. However, minor differences were found in the binding modes of "short" inverse agonist 6 and "long" inverse agonist 7h. To further reveal the molecular mechanisms of different RORγt inverse agonists, we performed molecular dynamics simulations and found that "short" or "long" inverse agonists led to different behaviors of helixes H11, H11', and H12 of RORγt. The "short" inverse agonist 6 destabilizes H11' and dislocates H12, while the "long" inverse agonist 7h separates H11 and unwinds H12. The results indicate that the two types of inverse agonists may behave differently in downstream signaling, which may help identify novel inverse agonists with different regulatory mechanisms.

Synthesis and biological evaluation of pyranocarbazole derivatives as Anti-tumor agents.

A series of pyrano[3,2-a]carbazole alkaloids were designed and synthesized as derivatives of Girinimbine. The anticancer activities of these derivatives (3, 4a-j, 5a, 5c, 5f, 5i, 6c, 7a, 7c, 7f, 7i) against 10 cancer cell lines were studied. Among them, compounds 3 and 7i with N-methyl piperazine showed significant anticancer activity against MCF-7 cell lines with the IC50 values of 1.77 and 4.32 µM, respectively. Furthermore, their effects on altering cell morphology, inducing cell cycle arrest and apoptosis in MCF-7 cells were studied in vitro. In addition, the molecular docking study was carried out by using Discovery Studio software to predict the interactions between these derivatives and tubulin. All in all, these consequences reveal that pyranocarbazole derivatives with N-methyl piperazine can be used as potential anticancer lead compounds and provide useful points for the further optimization of pyranocarbazole alkaloids.

Structure-activity relationship (SAR) studies on the mutagenic properties of 2,7-diaminofluorene and 2,7-diaminocarbazole derivatives.

We discovered that 2,7-diaminofluorene or 2,7-diaminocarbazole moiety can be employed as a core structure of highly effective NS5A inhibitors that are connected through amide bonds to proline-valine-carbamate motifs. Amide bonds can be easily cleaved via various metabolic pathways upon administration into the body, and metabolites containing 2,7-diaminofluorene and 2,7-diaminocarbazole core structures have been known to be strong mutagens. To avoid the mutagenesis issue of these core structures, we examined various functional groups at the C9 or N9 position of 2,7-diaminofluorene or 2,7-diaminocarbazole, respectively, through the Ames test in TA98 and TA100 mutants of Salmonella typhimurium LT-2. We discovered that, through proper alkyl substitution at the C9 or N9 position, 2,7-diaminofluorene and 2,7-diaminocarbazole moieties can be successfully employed in drug discovery without necessarily causing mutagenicity problems.