Synthesis of trifluoroethoxy/aryloxy cinnolines, cinnolinones and indazoles from o-alkynylanilines via metal-free diazotization reagent.

A facile and user-friendly protocol for the synthesis of trifluoroethoxy/aryloxy cinnolines, cinnolinones and indazoles from o-alkynylaniline in good-to-excellent yields has been developed using a metal-free diazotization reagent (a combination of BF3·OEt2 and TBN). The methodology has been further extended to construct bis-cinnolinones and for the chemoselective synthesis of N-propargylated cinnolinones.

Copper-Catalyzed Chemoselective O-Arylation of Oxindoles: Access to Cyclic Aryl Carboxyimidates.

We have developed a highly efficient base- and additive-free chemoselective CuO-catalyzed strategy for the O-arylation of 2-oxindoles to synthesize 2-phenoxy-3H-indole and 2-phenoxy-1H-indole derivatives in the presence of diaryl iodonium salts. This method offers a variety of O-arylated oxindoles in good to excellent yields under relatively milder reaction conditions. Furthermore, this methodology was extended for the O-arylation of 2-pyridinone and isoindoline-1-one derivatives as well.

Tunable Regio- and Stereoselective Synthesis of Z-Acrylonitrile Indoles and 3-Cyanoquinolines from 2-Alkynylanilines and Alkynylnitriles.

The merger of two bifunctional moieties, 2-alkynylaniline and alkynylnitriles, in the presence of ZnBr2 offers the tunable synthesis of two biologically important motifs: acrylonitrile indoles and 3-cyanoquinolines. The group present on the terminal alkyne of 2-alkynylaniline regulates the reaction pathways, intra- versus intermolecular, which thereby adds stereoselectivity and regioselectivity in this protocol. The conversion of an acrylonitrile indole ring to quinoline is an intriguing synthetic utility of this methodology.

Synthesis of Indole-Fused Dihydrothiopyrano Scaffolds via (3 + 3)-Annulations of Donor-Acceptor Cyclopropanes with Indoline-2-Thiones.

A new methodology for the synthesis of N-haloindole-fused dihydrothiopyrano derivatives via (3 + 3)-annulation of donor-acceptor cyclopropanes (DACs) with indoline-2-thiones in the presence of Sc(OTf)3 as a Lewis acid catalyst has been developed. This protocol provides a variety of indole-fused dihydrothiopyrano molecules in good to excellent yields, which architecturally resemble other indole-fused tricyclic molecules having potential medicinal value. In addition, we have described a detailed reaction mechanism and transformation of the furnished product into N-fused thiazino indole molecule.

AVA-NP-695 Selectively Inhibits ENPP1 to Activate STING Pathway and Abrogate Tumor Metastasis in 4T1 Breast Cancer Syngeneic Mouse Model.

Cyclic GMP-AMP synthase (cGAS) is an endogenous DNA sensor that synthesizes cyclic guanosine monophosphate-adenosine monophosphate (2'3'-cGAMP) from ATP and GTP. 2'3'-cGAMP activates the stimulator of interferon genes (STING) pathway, resulting in the production of interferons and pro-inflammatory cytokines. Ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) is the phosphodiesterase that negatively regulates the STING pathway by hydrolyzing 2'3'-cGAMP. It has been established that the cGAS-STING pathway plays a major role in inhibiting tumor growth by upregulating T cell response. Herein, we demonstrate that AVA-NP-695, a selective and highly potent ENPP1 inhibitor, apart from the immunomodulatory effect also modulates cancer metastasis by negatively regulating epithelial-mesenchymal transition (EMT). We established that the combined addition of 2'3'-cGAMP and AVA-NP-695 significantly abrogated the transforming growth factor beta (TGF-ꞵ)-induced EMT in MDA-MB-231 cells. Finally, results from the in vivo study showed superior tumor growth inhibition and impact on tumor metastasis of AVA-NP-695 compared to Olaparib and PD-1 in a syngeneic 4T1 breast cancer mouse model. The translation of efficacy from in vitro to in vivo 4T1 tumor model provides a strong rationale for the therapeutic potential of AVA-NP-695 against triple-negative breast cancer (TNBC) as an immunomodulatory and anti-metastatic agent.

Immunomodulatory effect of mycobacterial outer membrane vesicles coated nanoparticles.

Tuberculosis (TB) is one of the most widely prevalent infectious diseases that cause significant mortality. Bacillus Calmette-Guérin (BCG), the current TB vaccine used in clinics, shows variable efficacy and has safety concerns for immunocompromised patients. There is a need to develop new and more effective TB vaccines. Outer membrane vesicles (OMVs) are vesicles released by Mycobacteria that contain several lipids and membrane proteins and act as a good source of antigens to prime immune response. However, the use of OMVs as vaccines has been hampered by their heterogeneous size and low stability. Here we report that mycobacterial OMVs can be stabilized by coating over uniform-sized 50 nm gold nanoparticles. The OMV-coated gold nanoparticles (OMV-AuNP) show enhanced uptake and activation of macrophages and dendritic cells. Proteinase K and TLR inhibitor studies demonstrated that the enhanced activation was attributed to proteins present on OMVs and was mediated primarily by TLR2 and TLR4. Mass spectrometry analysis revealed several potential membrane proteins that were common in both free OMVs and OMV-AuNP. Such strategies may open up new avenues and the utilization of novel antigens for developing TB vaccines.

A metal-free BF3·OEt2 mediated chemoselective protocol for the synthesis of propargylic cyclic imines.

A chemoselective and metal/additive-free protocol for the synthesis of propargylic cyclic imine derivatives via (3 + 2)-cycloaddition of donor-acceptor cyclopropanes and alkynylnitriles in the presence of BF3·OEt2 has been established. The newly developed methodology provided access to a variety of propargylic cyclic imines in good to excellent yields. In addition, the synthesis of propargylic amines and the corresponding very stable enol derivatives from the title compound is also explored.

Ionic Liquid-Mediated One-Pot 3-Acylimino-3H-1,2-dithiole Synthesis from Thiocarboxylic Acids and Alkynylnitriles via In Situ Generation of Disulfide Intermediates.

A practical and straightforward strategy for the synthesis of 3-acylimino-3H-1,2-dithiol derivatives via a metal-free annulation reaction of alkynylnitriles with thiocarboxylic acids mediated by ionic liquids [BMIM]Br has been reported. This operationally simple protocol offers an easy and rapid access to a library of dithiol derivatives in moderate to good yields. The mechanistic studies show a benzoyldithio anion addition to alkynylnitriles followed by an annulation reaction through the involvement of a disulfide moiety as the key intermediate.

Cationic inhalable particles for enhanced drug delivery to M. tuberculosis infected macrophages.

Inhalable microparticle-based drug delivery platforms are being investigated extensively for Tuberculosis (TB) treatment as they offer efficient deposition in lungs and improved pharmacokinetics of the encapsulated cargo. However, the effect of physical parameters of microcarriers on interaction with Mycobacterium tuberculosis (Mtb) infected mammalian cells is underexplored. In this study, we report that Mtb-infected macrophages are highly phagocytic and microparticle surface charge plays a major role in particle internalization by infected cells. Microparticles of different sizes (0.5-2 µm) were internalized in large numbers by Mtb-infected THP-1 macrophages and murine primary Bone Marrow Derived Macrophages in vitro. Drastic improvement in particle uptake was observed with cationic particles in vitro and in mice lungs. Rapid uptake of rifampicin-loaded cationic microparticles allowed high intracellular accumulation of the drug and led to enhanced anti-bacterial function when compared to non-modified rifampicin-loaded microparticles. Cytocompatibility assay and histological analysis in vivo confirmed that the formulations were safe and did not elicit any adverse reaction. Additionally, pulmonary delivery of cationic particles in mice resulted in two-fold higher uptake in resident alveolar macrophages compared to non-modified particles. This study provides a framework for future design of drug carriers to improve delivery of anti-TB drugs inside Mtb-infected cells.

Leishmania survives by exporting miR-146a from infected to resident cells to subjugate inflammation.

Leishmania donovani, the causative agent of visceral leishmaniasis, infects and resides within tissue macrophage cells. It is not clear how the parasite infected cells crosstalk with the noninfected cells to regulate the infection process. During infection, Leishmania adopts a dual strategy for its survival by regulating the intercellular transport of host miRNAs to restrict inflammation. The parasite, by preventing mitochondrial function of host cells, restricts the entry of liver cell derived miR-122-containing extracellular vesicles in infected macrophages to curtail the inflammatory response associated with miR-122 entry. On contrary, the parasite up-regulates the export of miR-146a from the infected macrophages. The miR-146a, associated with the extracellular vesicles released by infected cells, restricts miR-122 production in hepatocytes while polarizing neighbouring naïve macrophages to the M2 state by affecting the cytokine expression. On entering the recipient macrophages, miR-146a dominates the miRNA antagonist RNA-binding protein HuR to inhibit the expression of proinflammatory cytokine mRNAs having HuR-interacting AU-rich elements whereas up-regulates anti-inflammatory IL-10 by exporting the miR-21 to polarize the recipient cells to M2 stage.

Design, synthesis and biological evaluation studies of novel small molecule ENPP1 inhibitors for cancer immunotherapy.

Ecto-nucleotide pyrophosphatase/phosphodiesterases 1 (ENPP1 or NPP1), is an attractive therapeutic target for various diseases, primarily cancer and mineralization disorders. The ecto-enzyme is located on the cell surface and has been implicated in the control of extracellular levels of nucleotide, nucleoside and (di) phosphate. Recently, it has emerged as a critical phosphodiesterase that hydrolyzes cyclic 2'3'- cGAMP, the endogenous ligand for STING (STimulator of INterferon Genes). STING plays an important role in innate immunity by activating type I interferon in response to cytosolic 2'3'-cGAMP. ENPP1 negatively regulates the STING pathway and hence its inhibition makes it an attractive therapeutic target for cancer immunotherapy. Herein, we describe the design, optimization and biological evaluation studies of a series of novel non-nucleotidic thioguanine based small molecule inhibitors of ENPP1. The lead compound 43 has shown good in vitro potency, stability in SGF/SIF/PBS, selectivity, ADME properties and pharmacokinetic profile and finally potent anti-tumor response in vivo. These compounds are a good starting point for the development of potentially effective cancer immunotherapy agents.

Transition-Metal-Free HFIP-Mediated Organo Chalcogenylation of Arenes/Indoles with Thio-/Selenocyanates.

We have developed a protocol for the synthesis of diaryl thio-/selenoethers by the reaction of aryl chalcogenocyanates with electron rich arenes/hetero arenes via HFIP promoted C-H activation. The reaction produces chalcogenides in good to excellent yields under mild conditions without the need of a transition metal as a catalyst. The HFIP-mediated reactions tolerated a wide range of functional groups and set the stage for the synthesis of diversely decorated chalcogenides. A mechanism involving activation of the C-H bond through hydrogen bonding is proposed.

Combatting intracellular pathogens using bacteriophage delivery.

Intracellular pathogens reside in specialised compartments within the host cells restricting the access of antibiotics. Insufficient intracellular delivery of antibiotics along with several other resistance mechanisms weaken the efficacy of current therapies. An alternative to antibiotic therapy could be bacteriophage (phage) therapy. Although phage therapy has been in practice for a century against various bacterial infections, the efficacy of phages against intracellular bacteria is still being explored. In this review, we will discuss the advancement and challenges in phage therapy, particularly against intracellular bacterial pathogens. Finally, we will highlight the uptake mechanisms and approaches to overcome the challenges to phage therapy against intracellular bacteria.

A periodic development of BPA and BSH based derivatives in boron neutron capture therapy (BNCT).

Boron neutron capture therapy (BNCT) is a particular type of radiotherapy that requires a selective and high concentration of boron accumulation in neoplastic cells. To distinguish the distribution of boron compounds between tumour and normal cells, multiple research groups have been involved and successively innovated a wide variety of boron-based compounds. Despite the development of numerous boron compounds, only boronophenylalanine (BPA) and sodium mercaptoundecahydro-closo-dodecaborate (BSH) have emerged as effective in clinical trials. Here, we highlight the detailed progress in the molecular design of BPA and BSH derivatives from the historical perspective to the latest advances in light of the widely accepted performance required for effective BNCT. In this report, we have provided an overview of a variety of derivatives of BPA and BSH, including amino acids, peptides, polymers, monoclonal antibodies and chelated complexes, and it is observed that such derivatives of BPA and BSH are judicious choices for BNCT. Finally, we have summarised the critical issues for BPA and BSH that must be addressed if BNCT is to become a more widely accepted clinical modality.

A novel microRNA boosts hyper-ß-oxidation of fatty acids in liver by impeding CEP350-mediated sequestration of PPARα and thus restricts chronic hepatitis C.

Imbalance in lipid metabolism induces steatosis in liver during Chronic hepatitis C (CHC). Contribution of microRNAs in regulating lipid homoeostasis and liver disease progression is well established using small RNA-transcriptome data. Owing to the complexity in the development of liver diseases, the existence and functional importance of yet undiscovered regulatory miRNAs in disease pathogenesis was explored in this study using the unmapped sequences of the transcriptome data of HCV-HCC liver tissues following miRDeep2.pl pipeline. MicroRNA-c12 derived from the first intron of LGR5 of chromosome 12 was identified as one of the miRNA like sequences retrieved in this analysis that showed human specific origin. Northern blot hybridization has proved its existence in the hepatic cell line. Enrichment of premiR-c12 in dicer-deficient cells and miR-c12 in Ago2-RISC complex clearly suggested that it followed canonical miRNA biogenesis pathway and accomplished its regulatory function. Expression of this miRNA was quite low in CHC tissues than normal liver implying HCV-proteins might be regulating its biogenesis. Promoter scanning and ChIP analysis further revealed that under expression of p53 and hyper-methylation of STAT3 binding site upon HCV infection restricted its expression in CHC tissues. Centrosomal protein 350 (CEP350), which sequestered PPARα, was identified as one of the targets of miR-c12 using Miranda and validated by luciferase assay/western blot analysis. Furthermore, reduced triglyceride accumulation and enhanced PPARα mediated transcription of ß-oxidation genes upon restoration of miR-c12 in liver cells suggested its role in lipid catabolism. Thus this study is reporting miR-c12 for the first time and showed its' protective role during chronic HCV infection.

The exosome encapsulated microRNAs as circulating diagnostic marker for hepatocellular carcinoma with low alpha-fetoprotein.

Diagnosis of hepatocellular carcinoma (HCC) remains challenging to clinicians, particularly in a patient with low alpha-fetoprotein. Here, in silico, ex vivo and in vitro data were combined to identify liver-specific exosomal miRNAs as an early diagnostic marker for HCC. Transcriptome profiling for mRNA and small RNA in same HCV-HCC and normal liver tissues followed by cross-validation of 41 deregulated miRNAs (log2 FoldChange > 1.5, Padj < .1) with GEO/TCGA datasets of HCV/HBV related HCC vs normal/adjacent tissue revealed three miRNAs were commonly deregulated (miR-10b/miR-21/miR-182) among all HCC irrespective of viral etiology. Targets of top deregulated miRNAs were identified by TargetScan/miRwalk and validated in mRNA transcriptome data followed by Panther/Gene Ontology enrichment/Cytoscape analysis suggested that targets were mostly from carcinogenesis pathways. Hence, those miRNAs were validated in normal and HCV-HCC tissues by qRT-PCR and subsequently in plasma-derived-exosomes of both HBV/HCV infected non-HCC (chronic hepatitis [CH]/liver cirrhosis [LC]) and HCC samples, and in liver-specific Anti-Asgr2 immuno-enriched exosomes. Exosomes were verified using Nanosight/TEM/immune-blotting with anti-Alix/anti-GRP78/anti-Asgr2. Along with miR-21-5p, miR-10b-5p/miR-221-3p/miR-223-3p was found significantly upregulated in the exosome of HCC patients than CH/non-HCC. The comparable expression pattern was seen in anti-Asgr2 immuno-precipitated exosomes. Interestingly, the AFP level was found below 250 ng/mL in about 94% of HCV-HCC and 62% of HBV-HCC patients. ROC analysis showed that miR-10b-5p + miR-221-3p + miR-223-3p + miR-21-5p could differentiate CH/non-HCC(CH + LC) from HCC with AUROC: 0.86 (97.5% CI: 0.77-0.94)/0.80 (97.5% CI: 0.70-0.89), sensitivity: 74%/58% and specificity: 86%/95% while miR-10b-5p + miR-221-3p + miR-223-3p showed AUROC: 0.84 (97.5% CI: 0.74-0.94)/0.74 (97.5% CI: 0.63-0.84), sensitivity: 86%/86% and specificity:66%/53% for low AFP-HCC vs CH/non-HCC, respectively, having better sensitivity than the combination of four miRNAs. Multivariate analysis further revealed low Albumin and high miR-21-5p as probable independent risk factor for HCC.

MicroRNA exporter HuR clears the internalized pathogens by promoting pro-inflammatory response in infected macrophages.

HuR is a miRNA derepressor protein that can act as miRNA sponge for specific miRNAs to negate their action on target mRNAs. Here we have identified how HuR, by inducing extracellular vesicles-mediated export of miRNAs, ensures robust derepression of miRNA-repressed cytokines essential for strong pro-inflammatory response in activated mammalian macrophages. Leishmania donovani, the causative agent of visceral leishmaniasis, on the contrary alters immune response of the host macrophage by a variety of complex mechanisms to promote anti-inflammatory response essential for the survival of the parasite. We have found that during Leishmania infection, the pathogen targets HuR to promote onset of anti-inflammatory response in mammalian macrophages. In infected macrophages, Leishmania also upregulate protein phosphatase 2A that acts on Ago2 protein to keep it in dephosphorylated and miRNA-associated form. This causes robust repression of the miRNA-targeted pro-inflammatory cytokines to establish an anti-inflammatory response in infected macrophages. HuR has an inhibitory effect on protein phosphatase 2A expression, and mathematical modelling of macrophage activation process supports antagonistic miRNA-modulatory roles of HuR and protein phosphatase 2A which mutually balances immune response in macrophage by targeting miRNA function. Supporting this model, ectopic expression of the protein HuR and simultaneous inhibition of protein phosphatase 2A induce strong pro-inflammatory response in the host macrophage to prevent the virulent antimonial drug-sensitive or drug-resistant form of L. donovani infection. Thus, HuR can act as a balancing factor of immune responses to curtail the macrophage infection process by the protozoan parasite.

Atom-Economic Route to Cyanoarenes and 2,2'-Dicyanobiarenes via Iron-Catalyzed Chemoselective [2 + 2 + 2] Cycloaddition Reactions of Diynes and Tetraynes with Alkynylnitriles.

An efficient protocol for the synthesis of cyanoarenes has been developed via an iron-catalyzed chemoselective [2 + 2 + 2] cycloaddition reaction of diynes with alkynylnitriles under mild reaction conditions with good to excellent yields. The reaction is catalyzed by the combination of FeCl2·4H2O as a metal source, 2-(2,6-diisopropylphenyl)iminomethylpyridine (dipimp) as a ligand, and Zn as a reducing agent in DME solvent. The protocol was further extended to the synthesis of 2,2'-dicyanobiarene skeletons from the reaction of tetraynes with alkynylnitriles.

Synthesis of 3-(2-thiopyridyl)indoles via the ruthenium catalyzed [2 + 2 + 2] cycloaddition of diynes and 3-thiocyanatoindoles.

A highly efficient protocol for the synthesis of 3-(2-thiopyridyl)indoles via the ruthenium(ii) catalyzed [2 + 2 + 2] cycloaddition reaction of α,ω-diynes with 3-thiocyanatoindoles under mild reaction conditions has been developed. A variety of 3-(2-thiopyridyl)indole derivatives were prepared by the reaction of the aforesaid substrates in the presence of a readily available chloro(pentamethylcyclopentadienyl)(cyclooctadiyne)ruthenium(ii) catalyst in ethanol with good to excellent yields. This atom economical methodology provides us efficient access to 3-(2-thiopyridyl)indole skeletons with close structural similarity to other pyridyl indole thioethers that have potential medicinal value.

Spatiotemporal Uncoupling of MicroRNA-Mediated Translational Repression and Target RNA Degradation Controls MicroRNP Recycling in Mammalian Cells.

MicroRNA (miRNA)-mediated repression controls expression of more than half of protein-coding genes in metazoan animals. Translation repression is associated with target mRNA degradation initiated by decapping and deadenylation of the repressed mRNAs. Earlier evidence suggests the endoplasmic reticulum (ER) as the site where microRNPs (miRNPs) interact with their targets before translation repression sets in, but the subcellular location of subsequent degradation of miRNA-repressed messages is largely unidentified. Here, we explore the subcellular distribution of essential components of degradation machineries of miRNA-targeted mRNAs. We have noted that interaction of target mRNAs with AGO2 protein on the ER precedes the relocalization of repressed messages to multivesicular bodies (MVBs). The repressed messages subsequently get deadenylated, lose their interaction with AGO2, and become decapped. Blocking maturation of endosomes to late endosome and MVBs by targeting the endosomal protein HRS uncouples miRNA-mediated translation repression from target RNA degradation. HRS is also targeted by the intracellular parasite Leishmania donovani, which curtails the HRS level in infected cells to prevent uncoupling of mRNA-AGO2 interaction, preventing degradation of translationally repressed messages, and thus stops recycling of miRNPs preengaged in repression.