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.

Chemical profile of the roots of Clausena lansium and their inhibitory effects of the over-activation in BV-2 microglial cells.

From the 95% ethanol aqueous extract of the roots of Clausena lansium, six previously undescribed alkaloids (1, 2a, 2b, 15, 24a, 24b), a pair of prenylated phenylpropenols (26a, 26b), two coumarins (27, 28), and two undescribed sesquiterpenes (37, 38) were isolated and identified using spectroscopic and electron circular dichroism data, together with thirty-two known compounds. The absolute configurations of three alkaloids (3a, 3b, 4a) were determined for the first time. In vitro assay showed that alkaloids 7, 10, 12, 19, and furanocoumarins 34, 35 displayed inhibitory effects on the production of nitric oxide in lipopolysaccharide (LPS)-induced BV-2 microglial cells, which were stronger than that of the minocycline (positive control). RT-PCR results indicated that indizoline (7) could inhibit the expression of pro-inflammatory factors (IL-1ß, TNF-α, and IL-6) in LPS-treated BV-2 cells.

Generation of streptocarbazoles with cytotoxicities by pathway engineering and insights into their biosynthesis.

Streptocarbazoles are a class of indolocarbazole (ICZ) compounds produced by Streptomyces strains that feature unique cyclic N-glycosidic linkages between the 1,3-carbon atoms of the glycosyl moiety and the two indole nitrogen atoms. Although several streptocarbazole compounds display effective cytotoxic activity, their biosynthesis remains unclear. Herein, through the inactivation of the aminotransferase gene spcI in the staurosporine biosynthetic gene cluster spc followed by heterologous expression, two new streptocarbazole derivatives (1 and 3) and three known ICZs (2, 4, and 5) were generated. Their structures were determined by a combination of spectroscopic methods, circular dichroism measurements, and single-crystal X-ray diffraction. Compounds 1-4 displayed moderate cytotoxicity against HCT-116 cell line, and compounds 3 and 4 were effective against Huh 7 cell line. Double-gene knockout experiments allowed us to propose a biosynthetic pathway for streptocarbazole productions. Furthermore, by overexpression of the involving key enzymes, the production of streptocarbazoles 1 and 3 were improved by approximately 1.5-2.5 fold. IMPORTANCE: Indolocarbazoles (ICZs) are a group of antitumor agents, with several analogs used in clinical trials. Therefore, the identification of novel ICZ compounds is important for drug discovery. Streptocarbazoles harbor unique N-glycosidic linkages (N13-C1' and N12-C3'), distinguishing them from the representative ICZ compound staurosporine; however, their biosynthesis remains unclear. In this study, two new streptocarbazoles (1 and 3) with cytotoxic activities were obtained by manipulating the staurosporine biosynthetic gene cluster spc followed by heterologous expression. The biosynthetic pathway of streptocarbazoles was proposed, and their productions were improved through the overexpression of the key enzymes involved. This study enriches the structural diversity of ICZ compounds and would facilitate the discovery of new streptocarbazoles via synthetic biological strategies.

Palindromic carbazole derivatives: unveiling their antiproliferative effect via topoisomerase II catalytic inhibition and apoptosis induction.

Human DNA topoisomerases are essential for crucial cellular processes, including DNA replication, transcription, chromatin condensation, and maintenance of its structure. One of the significant strategies employed in cancer treatment involves the inhibition of a specific type of topoisomerase, known as topoisomerase II (Topo II). Carbazole derivatives, recognised for their varied biological activities, have recently become a significant focus in oncological research. This study assesses the efficacy of three symmetrically substituted carbazole derivatives: 2,7-Di(2-furyl)-9H-carbazole (27a), 3,6-Di(2-furyl)-9H-carbazole (36a), and 3,6-Di(2-thienyl)-9H-carbazole (36b) - as anticancer agents. Among investigated carbazole derivatives, compound 3,6-di(2-furyl)-9H-carbazole bearing two furan moieties emerged as a novel catalytic inhibitor of Topo II. Notably, 3,6-di(2-furyl)-9H-carbazole effectively selectively inhibited the relaxation and decatenation activities of Topo IIα, with minimal effects on the IIß isoform. These findings underscore the potential of compound 3,6-Di(2-furyl)-9H-carbazole as a promising lead candidate warranting further investigation in the realm of anticancer drug development.

Computational molecular perspectives on novel carbazole derivative as an anti-cancer molecule against CDK1 of breast and colorectal cancers via gene expression studies, novel two-way docking strategies, molecular mechanics and dynamics.

With increase in cancer incidences, alternative strategies for disease management are of utmost importance. Carbazole, is a compound that is being studied extensively as an anti-cancer compound. In this work, we aimed to investigate a carbazole derivative against specific cancer types such as breast and colorectal, based on the off-target analyses of carbazole derivative. The present work shortlisted 6 proteins that have an association in both cancer types, and then employed two different molecular docking strategies to examine the binding stability of carbazole derivative: a blind-docking state, where the pockets were undefined and mutation-docking state, where possible mutations were induced within the proteins. The results showed that CDK1 bound best in both states to carbazole derivative, and performed better than an array of positive controls. Molecular dynamic simulations at 100 ns further proved its stability, with carbazole derivative-CDK1-blind and mutated complex having RMSD values between 3.2 and 3.6 Å, and 2.8-3.2 Šrespectively. Molecular-mechanics generalized born and surface area solvation disclosed free energy of binding for the complexes as -28.79 ± 3.97 kcal/mol and -31.86 ± 5.09 kcal/mol respectively, with carbazole derivative bound stably within the binding pocket at every 10 ns of the 100 ns trajectory. Radial distribution functions showed that the bell curve was well within 6 Å, thus showing that carbazole derivative and its atoms do not deviate away from the pocket, suggesting its ability to be used as a good anti-cancer compound against breast and colorectal.

Discovery of a far-red carbazole-benzoindolium fluorescent ligand that selectively targets mitochondrial DNA and suppresses breast cancer growth.

G-quadruplex (G4) formation was considered to be more prevalent in the mitochondrial DNA (mtDNA) of cancer cells compared with normal cells. Stabilization of these G4s may induce mtDNA instability and cause mitochondrial dysfunction and subsequent cell death, which may be treated as a new strategy for cancer treatment. However, few ligands were developed to target mtG4s, leaving a huge room to improve. In this study, we designed and synthesized a series of carbazole-based ligands, among which, BKN-1 was identified as the most promising mitochondrial targeting fluorescent ligand with far-red emission. Then, we demonstrated that BKN-1 may robustly interact with mtG4s via a variety of biophysical, biological experiments. Subsequently, we proved that BKN-1 may cause mtDNA loss, disrupt mitochondrial integrity, decrease ATP level and trigger unbalanced ROS, thereby leading to apoptosis and autophagy. Finally, we verified that BKN-1 had good anti-tumor activity in both cellular and in vivo models. Altogether, this study provided a dual-function ligand that may not only track the formation of mtG4s but also induce mitochondrial dysfunction, which may be developed into an applicable chemical tool for investigating the structure and function of mtG4s, and moreover, an effective therapeutic agent for cancer interference.

UltraFast PhotoInduced double duplex DNA invasion into a 400-mer dsDNA target.

BACKGROUND: Natural DNA restriction enzymes bind duplex DNA with high affinity at multiple sites; however, for some of the artificial chemical-based restriction moieties, invasion of the double-strand for efficient cleavage is an obstacle. We have previously reported photo-induced double-duplex invasion (pDDI) using 3-cyanovinylcarbazole (K)-containing probes for both the target strands that photo-crosslink with pyrimidine bases in a sequence-specific manner on both the strands, stabilizing the opened double-strand for cleavage. The drawback of the pDDI was low efficiency due to inter-probe cross-linking, solved by the inclusion of 5-cyano-uridine at -1 position on the complimentary strand with respect to K in both probes. Although this led to reduced inter-probe cross-linking, the pDDI efficiency was still low. RESULTS: Here, we report that inter-probe cross-linking and intra-probe cross-linking of a single probe is also leading to reduced pDDI efficiency. We addressed this problem by designing DDI probes to inhibit both inter-probe and intra-probe cross-linking. CONCLUSION: Based on the new design of pDDI probe with 5-cyano uridine led to a drastic increase in the efficiency of pDDI in (400-mer) double-stranded DNA with only 1 s of photo-irradiation.

Condition-Controlled Selective Synthesis of Pyranone-Tethered Indazoles or Carbazoles through the Cascade Reactions of N-Nitrosoanilines with Iodonium Ylides.

Presented herein is a condition-controlled selective synthesis of pyranone-tethered indazoles or carbazole derivatives via the cascade reactions of N-nitrosoanilines with iodonium ylides. Mechanistically, the formation of the former involves an unprecedented cascade process including nitroso group-directed C(sp2)-H bond alkylation of N-nitrosoaniline with iodonium ylide followed by intramolecular C-nucleophilic addition to the nitroso moiety, solvent-assisted cyclohexanedione ring opening, and intramolecular transesterification/annulation. On the contrary, the formation of the latter involves the initial alkylation followed by intramolecular annulation and denitrosation. These developed protocols feature easily controllable selectivity, mild reaction conditions, a clean and sustainable oxidant (air), and valuable products that are structurally diverse. In addition, the utility of the products was showcased by their facile and diverse transformations into synthetically and biologically interesting compounds.

Enantioselective binding of carvedilol to human serum albumin and alpha-1-acid glycoprotein.

Carvedilol, a highly protein-bound beta-blocker, is used in therapy as a racemic mixture of its two enantiomers that exhibit different pharmacological activity. The aim of this study was to evaluate the stereoselective nature of its binding to the two major plasma proteins: albumin and alpha-1-acid glycoprotein. The determination of the plasma protein-binding degree for carvedilol and its enantiomers was achieved using ultrafiltration for the separation of the free fraction, followed by LC-MS/MS quantification, using two different developed and validated methods in terms of stationary phase: achiral C18 type and chiral ovomucoid type. Furthermore, molecular docking methods were applied in order to investigate and to better understand the mechanism of protein-binding for S-(-)- and R-(+)-carvedilol. A difference in the binding behavior of the two enantiomers to the plasma proteins was observed when taken individually, with R-(+)-carvedilol having a higher affinity for albumin and S-(-)-carvedilol for alpha-1-acid glycoprotein. However, in the case of the racemic mixture, the binding of the S enantiomer to alpha-1-acid glycoprotein seemed to be influenced by the presence of its antipode, although no such influence was observed in the case of albumin. The results raise the question of a binding competition between the two enantiomers for alpha-1-acid glycoprotein.

Interaction of bifunctional peptide-carbazole complexes with DNA and antimicrobial activity.

Two peptide-carbazole conjugates, CTAT and CNLS, were designed and synthesized using carbazole Schiff base to modify the cell membrane penetrating peptide TAT (47-57) and the nuclear localization peptide NLS at the N terminus. The interaction with ctDNA was investigated by multispectral and agarose gel electrophoresis. And the effects of CNLS and CTAT on the G-quadruplex structure were explored by circular dichroism titration experiments. The results show that both CTAT and CNLS interact with ctDNA in a minor groove binding manner. Both conjugates bind more tightly to DNA than the individual substances CIBA, TAT and NLS. In addition, CTAT and CNLS are capable of unfolding parallel G-quadruplex structures and are potential G-quadruplex unfolding agents. Finally, broth microdilution was performed to test the antimicrobial activity of the peptides. The results showed that CTAT and CNLS had a 4-fold increase in antimicrobial activity compared with the parent peptides TAT and NLS. They could exert antimicrobial activity by disrupting the integrity of cell membrane bilayer and binding to DNA, and could be used as novel antimicrobial peptides for the development of novel antimicrobial antibiotics.

Switching Prenyl Donor Specificities in Squalene Synthase-Like Aromatic Prenyltransferases from Bacterial Carbazole Alkaloid Biosynthesis.

Lavanduquinocin (LDQ) is a potent neuroprotective carbazole alkaloid from Streptomyces species that features a rare cyclic monoterpene/cyclolavandulyl moiety attached to the tricyclic carbazole nucleus. We elucidated the biosynthetic logic of LDQ by enzymatically reconstituting the total biosynthetic pathway and identified the genes required for generating the cyclolavandulyl moiety in LDQ based on mutagenetic analysis, including a cyclolavandulyl diphosphate synthase gene ldqA and a squalene synthase-like aromatic prenyltransferase gene ldqG. LdqG is homologous to carbazole prenyltransferases, NzsG and CqsB4, discovered from the biosynthetic pathways of two bacterial carbazoles, neocarazostatin and carquinostatin. Based on analysis of the sequences and modeled protein structures, further in vitro and in vivo site-directed mutagenetic analyses led to identification of two residue sites, F53 and C57 in NzsG vs I54 and A58 in LdqG, which play crucial roles in governing the prenyl donor specificities toward cyclolavandulyl, dimethylallyl, and geranyl diphosphates. By applying this knowledge in strain engineering, prenyl donor delivery was rationally switched to produce the desired prenylated carbazoles. The study provides an opportunity to rationally manipulate the prenylation modification to carbazole alkaloids, which could influence the biological activities by increasing the affinity for membranes as well as the interactions with cellular targets.

Soil to earthworm bioaccumulation of polyhalogenated carbazoles and related compounds: Lab and field tests.

Polyhalogenated carbazoles (PHCZs) are an emerging group of organic contaminants that have attracted attention because of their ubiquity, resistance to biodegradation, and toxicities. However, studies on the bioaccumulation of PHCZs in terrestrial organisms are limited. In the present study, bioaccumulation of 11 PHCZs and two related compounds, carbazole (CZ) and benzocarbazole (BZCZ), from soil to earthworms was investigated by paired soil-earthworm samples from Hangzhou, China and a laboratory bioaccumulation test. The sum of the concentrations of the 11 polyhalogenated carbazoles (Σ11PHCZs), CZ and BZCZ in soils from Hangzhou were 1.78-67.27 ng/g dry weight, 1.11-57.90 ng/g dry weight, and 22.87-171.98 ng/g dry weight, respectively, while those in the earthworms were 179.49-892.90 ng/g lipid weight, 42.90-2140.42 ng/g lipid weight, and not detectable-2514.76 ng/g lipid weight, respectively. The average in situ biota-to-soil accumulation factors (BSAFs) ranged from 0.38 to 13.23, comparable to those in some reports for polychlorinated biphenyls and polybrominated diphenlethers. Site-independence of BSAFs and no correlation between log Cworm and log Csoil together support the hypothesis that distribution of PHCZs between soil and worms in Hangzhou didn't reach equilibrium. In the laboratory test, the accumulation trends of CZ, BZCZ, 3-bromocarbazole, 3,6-dichlorocarbazole, and 2,7-dibromocarbazole well fit to the first-order kinetics, with r2 ranging from 0.796 to 0.997. The BSAFs under two exposure concentration groups at steady-state conditions were 38.8-56.0 and 2.1-4.4, respectively, suggesting the capacity of bioaccumulation for these compounds. Enhancement of concentrations and resident time of the chemicals in soil would reduce the BSAF values, which may be related to the change of uptake process of the compound or redistribution of compound between soil and earthworm. A comparison of the theoretical steady-state concentrations with the nonlinear regression-based concentrations indicates that increasing the exposure time beyond 28 days is beneficial for studying the bioaccumulation of PHCZs.

Liquid Chromatography-High-Resolution Mass Spectrometry (LC-HRMS) Analysis Following Voluntary Carvedilol Poisoning in a Subject with Cirrhosis: A Case Report.

Accidental or intentional carvedilol poisoning is rarely reported. Here, we describe a case of attempted suicide with a large quantity of immediate-release carvedilol (75 mg) and alcohol. In order to determine the kinetics, liquid chromatography-high-resolution mass spectrometry analyses were performed. The results for the plasma concentration of carvedilol were 906 µg/L 3 h after ingestion, 288 µg/L 12 h after ingestion and 103 µg/L 24 h after ingestion. A one-compartment model with linear and first order best described the elimination of the carvedilol, and the estimated half-life was 5.8 h. The result 3 h after ingestion represented the highest concentration ever observed for this drug. However, the patient was cirrhotic, and liver function was impaired with decreased Factor V (45%) and prothrombin ratio (61%). These conditions may explain the high concentrations of carvedilol. The patient was treated with glucagon and discharged from the hospital the following day.

Visible-light-induced synthesis of N-disulfanyl indoles, pyrroles or carbazoles via the construction of stable S-S-N bonds.

A simple and efficient visible-light-induced approach for the formation of stable S-S-N bonds has been developed. Through these photocatalytic reactions, a series of N-disulfanyl indoles, pyrroles and carbazoles were afforded with good to excellent yields. Moreover, the gram-scale experiment has confirmed the practicability of this approach.

Bifunctional carbazole derivatives for simultaneous therapy and fluorescence imaging in prion disease murine cell models.

Prion diseases are characterized by the self-assembly of pathogenic misfolded scrapie isoforms (PrPSc) of the cellular prion protein (PrPC). In an effort to achieve a theranostic profile, symmetrical bifunctional carbazole derivatives were designed as fluorescent rigid analogues of GN8, a pharmacological chaperone that stabilizes the native PrPC conformation and prevents its pathogenic conversion. A focused library was synthesized via a four-step route, and a representative member was confirmed to have native fluorescence, including a band in the near-infrared region. After a cytotoxicity study, compounds were tested on the RML-infected ScGT1 neuronal cell line, by monitoring the levels of protease-resistant PrPSc. Small dialkylamino groups at the ends of the molecule were found to be optimal in terms of therapeutic index, and the bis-(dimethylaminoacetamido)carbazole derivative 2b was selected for further characterization. It showed activity in two cell lines infected with the mouse-adapted RML strain (ScGT1 and ScN2a). Unlike GN8, 2b did not affect PrPC levels, which represents a potential advantage in terms of toxicity. Amyloid Seeding Assay (ASA) experiments showed the capacity of 2b to delay the aggregation of recombinant mouse PrP. Its ability to interfere with the amplification of the scrapie RML strain by Protein Misfolding Cyclic Amplification (PMCA) was shown to be higher than that of GN8, although 2b did not inhibit the amplification of human vCJD prion. Fluorescent staining of PrPSc aggregates by 2b was confirmed in living cells. 2b emerges as an initial hit compound for further medicinal chemistry optimization towards strain-independent anti-prion compounds.

A Computational Study of Carbazole Alkaloids from Murraya koenigii as Potential SARS-CoV-2 Main Protease Inhibitors.

Despite COVID-19 vaccination, immune escape of new SARS-CoV-2 variants has created an urgent priority to identify additional antiviral drugs. Targeting main protease (Mpro) expressed by SARS-CoV-2 is a therapeutic strategy for drug development due to its prominent role in viral replication cycle. Leaves of Murraya koenigii are used in various traditional medicinal applications and this plant is known as a rich source of carbazole alkaloids. Thus, this computational study was designed to investigate the inhibitory potential of carbazole alkaloids from Murraya koenigii against Mpro. Molecular docking was initially used to determine the binding affinity and molecular interactions of carbazole alkaloids and the reference inhibitor (3WL) in the active site of SARS-CoV-2 Mpro (PDB ID: 6M2N).The top scoring compounds were further assessed for protein structure flexibility, physicochemical properties and drug-likeness, pharmacokinetic and toxicity (ADME/T) properties, antiviral activity, and pharmacophore modeling. Five carbazole alkaloids (koenigicine, mukonicine, o-methylmurrayamine A, koenine, and girinimbine) displayed a unique binding mechanism that shielded the catalytic dyad of Mpro with stronger binding affinities and molecular interactions than 3WL. Furthermore, the compounds with high affinity displayed favorable physicochemical and ADME/T properties that satisfied the criteria for oral bioavailability and druggability. The pharmacophore modeling study shows shared pharmacophoric features of those compounds for their biological interaction with Mpro. During the molecular dynamics simulation, the top docking complexes demonstrated precise stability except koenigicine. Therefore, mukonicine, o-methylmurrayamine A, koenine, and girinimbine may have the potential to restrict SARS-CoV-2 replication by inactivating the Mpro catalytic activity.

Assessing Carbazole Derivatives as Single-Electron Photoreductants.

The electron-donating capabilities of carbazoles have stimulated interest in their use as photoinduced single-electron reductants. Due to the modularity of the carbazole, a further broadening and understanding of their reactivity could be achieved by manipulating the structure. Herein, eight carbazole derivatives were synthesized, characterized, and assessed as single-electron photoreductants in the hydrodehalogenation of aryl halides and the arylation of N-methylpyrrole.

Rhodium catalysed intramolecular benzannulation for the formation of tetracyclic carbazoles.

Rhodium catalyzed alkyne-tethered intramolecular annulation has been demonstrated for the synthesis of tetracyclic carbazole skeletons and a series of five to eight-membered pyrido[3,2,1-jk]carbazoles were successfully obtained. The present atom economical annulation proceeded under mild reaction conditions, offering a broad substrate scope.

Novel nitric oxide-releasing derivatives of pyranocarbazole as antitumor agents: Design, synthesis, biological evaluation, and nitric oxide release studies.

In this study, a series of novel furoxan-based nitric oxide (NO) releasing derivatives of pyranocarbazole alkaloids were designed, synthesized, and biologically evaluated against human cancer cell lines. The derivatives showed considerable antiproliferative activities (IC50 = 0.05-7.55 µM) and most compounds showed higher activity in MDA-MB-231 than H460 and HeLa. Especially, the most active derivative 7a (IC50 = 0.05 µM) against MDA-MB-231 was about 60 times stronger than lead compound, as well as equivalent to positive control taxol, and produced high levels of NO in MDA-MB-231. Furthermore, 7a could significantly inhibit the growth of MDA-MB-231 tumors in vivo with low toxicity and the PI3K/Akt signaling pathway. These results indicated that compound 7a could be a promising lead for further studies.

Rhodium(I)-catalyzed directed trideuteromethylation of (hetero)arene C-H bonds with CD3CO2D.

A Rh(I)-catalyzed trideuteromethylation of heteroarenes with inexpensive and readily available deuterated acetic acid (CD3CO2D) with the aid of a N-containing directing groups is developed. The oxidant-free reaction is applicable to a wide range of heteroarene substrates, including 2-pyridones, indoles, aryl rings, pyrroles and carbazoles. It allows installation of CD3 groups under straightforward reaction conditions. It is expected that the salient and practical features of this trideuteromethylation protocol will be of use to academic and industrial researchers.