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Abstract: The syntheses of three novel analogues of the naturally occurring cytotoxic agent COTC are described and the results of bioassays of the target compounds against two lung cancer cell lines are presented. [Copyright &y& Elsevier]

Abstract: An expedient synthetic route to the fully substituted pyrrolidine ring system of the plakoridines is described using an approach modeled on a plausible biosynthetic pathway. [Copyright &y& Elsevier]

Eeyarestatin 1 (ES1) is an inhibitor of endoplasmic reticulum (ER) associated protein degradation, Sec61‐dependent Ca2+ homeostasis and protein translocation into the ER. Recently, evidence was presented showing that a smaller analog of ES1, ES24, targets the Sec61‐translocon, and captures it in an open conformation that is translocation‐incompetent. We now show that ES24 impairs protein secretion and membrane protein insertion in Escherichia coli via the homologous SecYEG‐translocon. Transcriptomic analysis suggested that ES24 has a complex mode of action, probably involving multiple targets. Interestingly, ES24 shows antibacterial activity toward clinically relevant strains. Furthermore, the antibacterial activity of ES24 is equivalent to or better than that of nitrofurantoin, a known antibiotic that, although structurally similar to ES24, does not interfere with SecYEG‐dependent protein trafficking. Like nitrofurantoin, we find that ES24 requires activation by the NfsA and NfsB nitroreductases, suggesting that the formation of highly reactive nitroso intermediates is essential for target inactivation in vivo. [ABSTRACT FROM AUTHOR]

A broad range of 1,10-phenanthroline substrates was efficiently C–H functionalised, providing rapid, gram-scale access to substituted heteroaromatic cores of broad utility. Furthermore, this C–H functionalisation pathway was extended to the synthesis of previously inaccessible, ultra-soluble, 2,9-bis-triazinyl-1,10-phenanthroline (BTPhen) ligands for advanced nuclear fuel cycles. [ABSTRACT FROM AUTHOR]

The first hydrophilic, 1,10-phenanthroline derived ligands consisting of only C, H, O and N atoms for the selective extraction of Am(iii) from spent nuclear fuel are reported herein. One of these 2,9-bis-triazolyl-1,10-phenanthroline (BTrzPhen) ligands combined with a non-selective extracting agent, was found to exhibit process-suitable selectivity for Am(iii) over Eu(iii) and Cm(iii), providing a clear step forward. [ABSTRACT FROM AUTHOR]

The first examples of 4,7-disubstituted 2,9-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzo-triazin-3-yl)-1,10-phenanthroline (CyMe4-BTPhen) ligands are reported herein. Evaluating the kinetics, selectivity and stoichiometry of actinide(iii) and lanthanide(iii) radiotracer extractions has provided a mechanistic insight into the extraction process. For the first time, it has been demonstrated that metal ion extraction kinetics can be modulated by backbone functionalisation and a promising new CHON compliant candidate ligand with enhanced metal ion extraction kinetics has been identified. The effects of 4,7-functionalisation on the equilibrium metal ion distribution ratios are far more pronounced than those of 5,6-functionalisation. The complexation of Cm(iii) with two of the functionalised ligands was investigated by TRLFS and, at equilibrium, species of 1 : 2 [M : L] stoichiometry were observed exclusively. A direct correlation between the ELUMO–EHOMO energy gap and metal ion extraction potential is reported, with DFT studies reaffirming experimental findings. [ABSTRACT FROM AUTHOR]

High yielding and diastereoselective conjugate addition reactions of a (−)-quinic acid derived enone have provided access to a small library of hybrid analogues of the anti-tumour natural products antheminone A and COTC. The novel compounds were assessed for their antiproliferative activities towards the A549 non-small-cell lung cancer cell line revealing some useful structure-activity relationships. [ABSTRACT FROM AUTHOR]

The unexpected discovery of an eliminative deprotection and cyclodimerization cascade reaction sequence led to the preparation of a series of perhydrodibenzofuranones that bear a structural resemblance to the natural product incarviditone. One of the novel dimers was found to show significant antiproliferative activity towards a non-small-cell lung cancer cell line, and represents a useful lead compound for the discovery of more potent anti-cancer agents. [ABSTRACT FROM AUTHOR]

Abstract: A synthetic approach to analogues of the terpenoid natural product antheminone A is described which employs (−)-quinic acid as starting material. A key conjugate addition step proved to be unpredictable regarding its stereochemical outcome however the route allowed access to two diastereoisomeric series of compounds. The results of biological assay of the toxicity of the target compounds towards non-small-cell lung cancer cell line A549 are reported. [Copyright &y& Elsevier]

IL-1β is a potent pro-inflammatory cytokine produced in response to infection or injury. It is synthesized as an inactive precursor that is activated by the protease caspase-1 within a cytosolic molecular complex called the inflammasome. Assembly of this complex is triggered by a range of structurally diverse damage or pathogen associated stimuli, and the signaling pathways through which these act are poorly understood. Ubiquitination is a post-translational modification essential for maintaining cellular homeostasis. It can be reversed by deubiquitinase enzymes (DUBs) that remove ubiquitin moieties from the protein thus modifying its fate. DUBs present specificity toward different ubiquitin chain topologies and are crucial for recycling ubiquitin molecules before protein degradation as well as regulating key cellular processes such as protein trafficking, gene transcription, and signaling. We report here that small molecule inhibitors of DUB activity inhibit inflammasome activation. Inhibition of DUBs blocked the processing and release of IL-1β in both mouse and human macrophages. DUB activity was necessary for inflammasome association as DUB inhibition also impairedASColigomerization and caspase-1 activation without directly blocking caspase-1 activity. These data reveal the requirement for DUB activity in a key reaction of the innate immune response and highlight the therapeutic potential of DUB inhibitors for chronic auto-inflammatory diseases. [ABSTRACT FROM AUTHOR]

Selective small-molecule inhibitors represent powerful tools for the dissection of complex biological processes. ESI (eeyarestatin I) is a novel modulator of ER (endoplasmic reticulum) function. In the present study, we show that in addition to acutely inhibiting ERAD(ER-associated degradation), ESI causes production of mislocalized polypeptides that are ubiquitinated and degraded. Unexpectedly, our results suggest that these non-translocated polypeptides promote activation of the UPR (unfolded protein response), and indeed we can recapitulate UPR activation with an alternative and quite distinct inhibitor of ER translocation. These results suggest that the accumulation of non-translocated proteins in the cytosol may represent a novel mechanism that contributes to UPR activation. [ABSTRACT FROM AUTHOR]

Imidazoacridin-6-ones are shown to be potent nanomolar inhibitors of the enzyme NQO2. By use of computational molecular modeling, a reliable QSAR was established, relating inhibitory potency with calculated binding affinity. Further, crystal structures of NQO2 containing two of the imidazoacridin-6-ones have been solved. To generate compounds with reduced off-target (DNA binding) effects, an N-oxide moiety was introduced into the tertiary aminoalkyl side chain of the imidazoacridin-6-ones. This resulted in substantially less toxicity in a panel of eight cancer cell lines, decreased protein binding, and reduced DNA binding and nuclear accumulation. Finally, one of the N-oxides showed potent ability to inhibit the enzymatic function of NQO2 in cells, and therefore, it may be useful as a pharmacological probe to study the properties of the enzyme in vitro and in vivo. [ABSTRACT FROM AUTHOR]

Abstract: The syntheses of five novel 2-oxyalkyl-cyclohex-2-enones, structurally related to the natural products COTC and antheminone A, are described. The target structures were selected in order to probe the influence of several key structural parameters on in vitro anti-cancer bioactivity. The results of a cytotoxicity bioassay of the compounds against non-small-cell lung cancer cell lines A549 and H460 are reported. The biological data provides useful information, which will help guide the future design of compounds in this class with enhanced anti-cancer activity. [ABSTRACT FROM AUTHOR]

Abstract: A range of triazoloacridin-6-ones functionalized at C5 and C8 have been synthesized and evaluated for ability to inhibit NQO1 and NQO2. The compounds were computationally docked into the active site of NQO1 and NQO2, and calculated binding affinities were compared with IC50 values for enzyme inhibition. Excellent correlation coefficients were demonstrated suggesting a predictive QSAR model for this series of structurally similar analogues. From this we have identified some of these triazoloacridin-6-ones to be the most potent NQO2 inhibitors so far reported. [Copyright &y& Elsevier]

Abstract: Syntheses of three novel analogues of the Streptomyces metabolite COTC are described, using the versatile chiral pool starting material, (−)-quinic acid. The results of bioassays of the target compounds against two lung cancer cell lines, A549 and H460, are presented. [Copyright &y& Elsevier]

Abstract: The synthesis of 6-epi-COTC, a diastereoisomer of Streptomyces metabolite 2-crotonyloxymethyl-(4R,5R,6R)-4,5,6-trihydroxycyclohex-2-enone (COTC), is described. The anti-cancer activities of the novel analogue, in racemic and enantiomerically pure forms, are presented. [Copyright &y& Elsevier]

Abstract: The pyrrolidine natural products, plakoridines A and B, as well as an array of unnatural analogues, have been prepared using a five-step synthetic sequence modelled on a biogenetic theory. The key transformation involves a ‘Mannich/Michael/internal-redox’ cascade, which proceeds in yields of 31–63%. [Copyright &y& Elsevier]

Abstract: An array of novel analogues of the marine oxylipins, the manzamenones and plakoridines, have been prepared in divergent fashion using an approach modelled on a biogenetic theory. Many of the target compounds show potent inhibition of DNA polymerases α and β and human terminal deoxynucleotidyl transferase (TdT). [Copyright &y& Elsevier]

Abstract: The synthesis of 6,6-difluoroshikimic acid ( 11 ) has been achieved in ten steps from the enantiopure diol 16 , which is derived from enzymatic cis-dihydroxylation of iodobenzene. The versatility of the synthetic strategy has been demonstrated by the preparation of the known antimicrobial agent, (6S)-6-fluoroshikimic acid ( 5 ). [Copyright &y& Elsevier]

The synthesis of 6,6-difluoroshikimic acid (4) has been achieved in nine steps from the enantiopure diol 9, which is derived from microbial dihydroxylation of iodobenzene. The synthetic strategy has also been demonstrated to be applicable to the preparation of other 6-substituted analogues of shikimic acid. [Copyright &y& Elsevier]

Investigations into the quinate to shikimate transformation have been carried out, the results of which have been exploited in the synthesis of a novel difluoromethylene homologue of shikimic acid from (−)-quinic acid. Martin''s sulfurane {Ph2S[OC(CF3)2Ph]2} was the reagent of choice for the key dehydration step of this synthesis. The results of investigations into the synthesis of the important natural product analogue, 6,6-difluoroshikimic acid are also reported. [Copyright &y& Elsevier]

Eeyarestatin 1 (ES1) inhibits p97-dependent protein degradation, Sec61-dependent protein translocation into the endoplasmic reticulum (ER), and vesicular transport within the endomembrane system. Here, we show that ES1 impairs Ca2+ homeostasis by enhancing the Ca2+ leakage from mammalian ER. A comparison of various ES1 analogs suggested that the 5-nitrofuran (5-NF) ring of ES1 is crucial for this effect. Accordingly, the analog ES24, which conserves the 5-NF domain of ES1, selectively inhibited protein translocation into the ER, displayed the highest potency on ER Ca2+ leakage of ES1 analogs studied and induced Ca2+-dependent cell death. Using small interfering RNA-mediated knockdown of Sec61α, we identified Sec61 complexes as the targets that mediate the gain of Ca2+ leakage induced by ES1 and ES24. By interacting with the lateral gate of Sec61α, ES1 and ES24 likely capture Sec61 complexes in a Ca2+-permeable, open state, in which Sec61 complexes allow Ca2+ leakage but are translocation incompetent. • ES1, ES2, and ES24 deplete Ca2+ in ER • ESR35 and ES47 do not affect cellular Ca2+ homeostasis • The most potent eeyarestatin, ES24, comprises only the 5-nitrofuran domain • ES1 and ES24 target Sec61 complexes in ER Gamayun et al. discovered that eeyarestatins (ESs) interfere with closing mechanisms of Sec61 complexes of the ER and, as a "foot in the door," stabilize Sec61 complexes in a Ca2+-permeable, open state. Specifically, ES24 enhances strongly the Sec61-mediated Ca2+ leakage from ER and induces Ca2+-dependent cell death. [ABSTRACT FROM AUTHOR]

The toxicity of the novel dimers (I) towards the Non-Small-Cell Lung Cancer Line A548 is assessed in view of the discovery of antiproliferative agents. [ABSTRACT FROM AUTHOR]