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Telomerase is a key component of the telomere length maintenance system in the majority of eukaryotes. Telomerase displays maximal activity in stem and cancer cells with high proliferative potential. In humans, telomerase activity is regulated by various mechanisms, including the interaction with telomere ssDNA overhangs that contain a repetitive G-rich sequence, and with noncoding RNA, Telomeric repeat-containing RNA (TERRA), that contains the same sequence. So these nucleic acids can compete for telomerase RNA templates in the cell. In this study, we have investigated the ability of different model substrates mimicking telomere DNA overhangs and TERRA RNA to compete for telomerase in vitro through a previously developed telomerase inhibitor assay. We have shown in this study that RNA oligonucleotides are better competitors for telomerase that DNA ones as RNA also use an alternative binding site on telomerase, and the presence of 2′-OH groups is significant in these interactions. In contrast to DNA, the possibility of forming intramolecular G-quadruplex structures has a minor effect for RNA binding to telomerase. Taking together our data, we propose that TERRA RNA binds better to telomerase compared with its native substrate - the 3′-end of telomere DNA overhang. As a result, some specific factor may exist that participates in switching telomerase from TERRA to the 3′-end of DNA for telomere elongation at the distinct period of a cell cycle in vivo. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Mixed(HCl)N(H2O)Mclusters have been assembled in He droplets fromthe constituting molecules. Spectra of the clusters were obtainedin the range of hydrogen-bonded OH vibrations (3100–3700 cm–1) by infrared laser depletion spectroscopy. The observedbands were assigned to cyclic hydrogen-bonded aggregates containingup to two HCl and three H2O molecules. The obtained frequenciesare in good agreement with the results of harmonic quantum chemicalcalculations upon appropriate uniform shifts mimicking anharmoniccorrections. Although larger clusters containing up to six water moleculeswere also produced in the droplets, their spectra were found to contributeto the unresolved signal in the range 3250–3550 cm–1. The fact that no narrow bands could be unambiguously assigned tothe mixed clusters containing more than three water molecules mayindicate that such clusters exist in many isomeric forms that leadto overlapped and unresolved bands giving rise to broad structurelessfeatures. Another possible explanation includes the formation of elusivezwitterionic clusters, whose bands may have considerable breadth dueto electrostatic coupling of different vibrational modes and concomitantintramolecular vibrational relaxation. [ABSTRACT FROM AUTHOR]

Azacarbazoles have attracted significant interest due to their valuable properties, such as anti-pathogenic and antitumor activity. In this study, a series of structurally related tricyclic benzo[4,5]- and tertacyclic naphtho[2′,1′:4,5]imidazo[1,2-c]pyrimidinone derivatives with one or two positively charged tethers were synthesized and evaluated for anti-proliferative activity. Lead tetracyclic derivative 5b with two amino-bearing arms inhibited the metabolic activity of A549 lung adenocarcinoma cells with a CC50 value of 3.6 μM, with remarkable selectivity (SI = 17.3) over VA13 immortalized fibroblasts. Cell-cycle assays revealed that 5b triggers G2/M arrest without signs of apoptosis. A study of its interaction with various DNA G4s and duplexes followed by dual luciferase and intercalator displacement assays suggests that intercalation, rather than the modulation of G4-regulated oncogene expression, might contribute to the observed activity. Finally, a water-soluble salt of 5b was shown to cause no acute toxic effects, changes in mice behavior, or any decrease in body weight after a 72 h treatment at concentrations up to 20 mg/kg. Thus, 5b is a promising candidate for studies in vivo; however, further investigations are needed to elucidate its molecular target(s). [ABSTRACT FROM AUTHOR]

Tubulin-targeting agents attract undiminished attention as promising compounds for the design of anti-cancer drugs. Verubulin is a potent tubulin polymerization inhibitor, binding to colchicine-binding sites. In the present work, a series of verubulin analogues containing a cyclohexane or cycloheptane ring 1,2-annulated with pyrimidine moiety and various substituents in positions 2 and 4 of pyrimidine were obtained and their cytotoxicity towards cancer and non-cancerous cell lines was estimated. The investigated compounds revealed activity against various cancer cell lines with IC50 down to 1–4 nM. According to fluorescent microscopy data, compounds that showed cytotoxicity in the MTT test disrupt the normal cytoskeleton of the cell in a pattern similar to that for combretastatin A-4. The hit compound (N-(4-methoxyphenyl)-N,2-dimethyl-5,6,7,8-tetrahydroquinazolin-4-amine) was encapsulated in biocompatible nanocontainers based on Ca2+ or Mg2+ cross-linked alginate and it was demonstrated that its cytotoxic activity was preserved after encapsulation. [ABSTRACT FROM AUTHOR]

The treatment of many bacterial diseases remains a significant problem due to the increasing antibiotic resistance of their infectious agents. Among others, this is related to Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA) and Mycobacterium tuberculosis. In the present article, we report on antibacterial compounds with activity against both S. aureus and MRSA. A straightforward approach to 2-(1H-indol-3-yl)quinazolin-4(3H)-one and their analogues was developed. Their structural and functional relationships were also considered. The antimicrobial activity of the synthesized compounds against Mycobacterium tuberculosis H37Rv, S. aureus ATCC 25923, MRSA ATCC 43300, Candida albicans ATCC 10231, and their role in the inhibition of the biofilm formation of S. aureus were reported. 2-(5-Iodo-1H-indol-3-yl)quinazolin-4(3H)-one (3k) showed a low minimum inhibitory concentration (MIC) of 0.98 μg/mL against MRSA. The synthesized compounds were assessed via molecular docking for their ability to bind long RSH (RelA/SpoT homolog) proteins using mycobacterial and streptococcal (p)ppGpp synthetase structures as models. The cytotoxic activity of some synthesized compounds was studied. Compounds 3c, f, g, k, r, and 3z displayed significant antiproliferative activities against all the cancer cell lines tested. Indolylquinazolinones 3b, 3e, and 3g showed a preferential suppression of the growth of rapidly dividing A549 cells compared to slower growing fibroblasts of non-tumor etiology. [ABSTRACT FROM AUTHOR]

Prostate cancer is the second most common cancer among men. We designed and synthesized new ligands targeting prostate-specific membrane antigen and suitable for bimodal conjugates with diagnostic and therapeutic agents. In vitro studies of the affinity of the synthesized compounds to the protein target have been carried out. Based on these ligands, a series of bimodal conjugates with a combination of different mitosis inhibitors and antiandrogenic drugs were synthesized. The cytotoxicity of the compounds obtained in vitro was investigated on three different cell lines. The efficacy of the two obtained conjugates was evaluated in vivo in xenograft models of prostate cancer. These compounds have been shown to be highly effective in inhibiting the growth of PSMA-expressing tumors. [ABSTRACT FROM AUTHOR]

Novel hydantion and thiohydantoin-based spiro-compounds were prepared via theDiels–Alder reactions between 5-methylidene-hydantoins or 5-methylidene-2-thiohydantoins and 1,3-dienes (cyclopentadiene, cyclohexadiene, 2,3-dimethylbutadiene, isoprene). It was shown that the cycloaddition reactions proceed regioselectively and stereoselectively with the formation of exo-isomers in the reactions with cyclic dienes andthe less sterically hindered products in the reactions with isoprene. Reactions of methylideneimidazolones with cyclopentadiene proceed viaco-heating the reactants; reactions with cyclohexadiene, 2,3-dimethylbutadiene, and isoprene require catalysis by Lewis acids. It was demonstrated that ZnI2 is an effective catalyst in the Diels–Alder reactions of methylidenethiohydantoins with non-activated dienes. The possibility of alkylation and acylation of the obtained spiro-hydantoinsat the N(1)nitrogen atoms with PhCH2Cl or Boc2O and the alkylation of the spiro-thiohydantoinsat the S atoms with MeI or PhCH2Cl in high yields have been demonstrated. The preparativetransformation of spiro-thiohydantoins into corresponding spiro-hydantoinsin mild conditions by treating with 35% aqueous H2O2 or nitrile oxide has been carried out. The obtained compounds show moderate cytotoxicity in the MTT test on MCF7, A549, HEK293T, and VA13 cell lines. Some of the tested compounds demonstrated some antibacterial effect against Escherichia coli (E. coli) BW25113 DTC-pDualrep2 but were almost inactive against E. coli BW25113 LPTD-pDualrep2. [ABSTRACT FROM AUTHOR]

Novel variously substituted thiohydantoin-based dispiro-indolinones were prepared using a regio- and diastereoselective synthetic route from 5-arylidene-2-thiohydantoins, isatines, and sarcosine. The obtained molecules were subsequently evaluated in vitro against the cancer cell lines LNCaP, PC3, HCTwt, and HCT(−/−). Several compounds demonstrated a relatively high cytotoxic activity vs. LNCaP cells (IC50 = 1.2–3.5 µM) and a reasonable selectivity index (SI = 3–10). Confocal microscopy revealed that the conjugate of propargyl-substituted dispiro-indolinone with the fluorescent dye Sulfo-Cy5-azide was mainly localized in the cytoplasm of HEK293 cells. P388-inoculated mice and HCT116-xenograft BALB/c nude mice were used to evaluate the anticancer activity of compound 29 in vivo. Particularly, the TGRI value for the P388 model was 93% at the final control timepoint. No mortality was registered among the population up to day 31 of the study. In the HCT116 xenograft model, the compound (170 mg/kg, i.p., o.d., 10 days) provided a T/C ratio close to 60% on day 8 after the treatment was completed. The therapeutic index—estimated as LD50/ED50—for compound 29 in mice was ≥2.5. Molecular docking studies were carried out to predict the possible binding modes of the examined molecules towards MDM2 as the feasible biological target. However, such a mechanism was not confirmed by Western blot data and, apparently, the synthesized compounds have a different mechanism of cytotoxic action. [ABSTRACT FROM AUTHOR]

A design of Pt(IV) prodrugs with tumor cell targeting moieties leading to increased selectivity is of interest. Herein, we designed a novel Pt(IV) prodrugs with COX-inhibitor naproxen, long-chain hydrophobic stearic acid moiety and biotin as axial ligands. We have established that for Pt(IV) prodrugs with biotin and naproxen or stearate in axial position, the lipophilicity rather than biotin receptors expression is the main factor of cytotoxicity. We also monitored the reduction speed of Pt(IV) prodrug 3 with naproxen and biotin in axial positions in A549 cells using XANES and demonstrated that the prodrug gradually releases cisplatin within 20 hours of incubation. [ABSTRACT FROM AUTHOR]

Purpose: Liver cancers are among the deadliest malignancies due to a limited efficacy of early diagnostics, the lack of appropriate biomarkers and insufficient discrimination of different types of tumors by classic and molecular methods. In this study, we searched for novel long non-coding RNA (lncRNA) as well as validated several known candidates suitable as probable biomarkers for primary liver tumors of various etiology. Methods: We described a novel lncRNA HELIS (aka "HEalthy LIver Specific") and estimated its expression by RT-qPCR in 82 paired tissue samples from patients with hepatocellular carcinoma (HCC), cholangiocarcinoma (CCA), combined HCC-CCA, pediatric hepatoblastoma (HBL) and non-malignant hepatocellular adenoma (HCA) and focal nodular hyperplasia (FNH). Additionally, we examined expression of cancer-associated lncRNAs HULC, MALAT1, UCA1, CYTOR, LINC01093 and H19, which were previously studied mainly in HCC. Results: We demonstrated that down-regulation of HELIS strongly correlates with carcinogenesis; whereas in tumors with non-hepatocyte origin (HBL, CCA) or in a number of poorly differentiated HCC, this lncRNA is not expressed. We showed that recently discovered LINC01093 is dramatically down-regulated in all malignant liver cancers; while in benign tumors LINC01093 expression is just twice decreased in comparison to adjacent samples. Conclusion: Our study revealed that among all measured biomarkers only down-regulated HELIS and LINC01093, up-regulated CYTOR and dysregulated HULC are perspective for differential diagnostics of liver cancers; whereas others demonstrated discordant results and cannot be considered as potential universal biomarkers for this purpose. [ABSTRACT FROM AUTHOR]

Selective ligands of an urea-based prostate specific membrane antigen with a phenylalanine/tyrosine-based dipeptide linker and with a mingled chiral centers configuration and/or substituted aromatic fragments were prepared in seven steps by liquid- and in six steps by solid-phase synthesis. In vitro test for inhibiting the cleavage of N -acetylaspartylglutamate revealed the optimum linker containing l -phenylalanine in the structure on the N-terminus of a dipeptide chain. [ABSTRACT FROM AUTHOR]

New copper(II) complexes of 2-alkylthio-5-arylmethylene-4H-imidazolin-4-ones: (5Z)-2-(methylsulfanyl)-3-(prop-2-en-1-yl)-5-(pyridin-2-ylmethylidene)-3,5-dihydro-4H-imidazol-4-one) ( 1a ), (5Z,5′Z)-2,2′-(ethan-1,2-diyldisulfanyldiyl)bis(5-(2-pyridilmethylen)-3-allyl-3,5-dihydo-4Н-imidazole-4-one) ( 2a ) and (5Z,5′Z)-3,3′-hexan-1,6-diylbis[5-(2-pyridilmethylen)-2-methylthiotetrahydro-4Н-imidazole-4-one)] ( 3a ) were synthesized as possible anticancer drugs. Their structures were characterized by 1 H NMR spectroscopy, elemental analysis, and X-ray crystallography. The composition of the complexes were found for 1a (Cu:L = 1 : 1 ), 2a (Cu:L = 2 : 1 ), and 3a (Cu:L = 2 : 1 ). The chelation constants were found by competitive complexation with ethylenediamine tetraacetate: 1a (6.7 ± 0.6) × 10 15 M − 1 , 2a = (4.9 ± 0.4) × 10 19 M − 2 , and 3a (5.7 ± 0.5) × 10 19 M − 2 . Supramolecular binding with calf thymus DNA by competitive ethidium bromide quenching was made for complex 2a as the most promising anticancer model, the Stern–Volmer constants were found to be K SV = (8.0 ± 0.4) × 10 6 M − 1 , K q = (6.5 ± 0.4) × 10 5 M − 1 . The binding of the complex 2a to BSA was made by the Scatchard method, the value of the constant is K b = (1.9 ± 0.2) × 10 6 M − 1 . [ABSTRACT FROM AUTHOR]

New allobetulin conjugates were obtained through its O-esterification with hex-5-ynoic acid followed by [3+2]-cycloaddition with three azido derivatives of N -acetyl- d -galactosamine. The conjugates are non-toxic in micromolar range against hepatocellular carcinoma cell lines and have a high affinity towards the HO asialoglycoprotein receptor of hepatocytes based on molecular docking and surface plasmon resonance data. [ABSTRACT FROM AUTHOR]

The synthesis and characterisation of novel thioacetyl-functionalised terpyridine ligands and their ruthenium and rhodium complexes [Ru(tpy) 2 ](PF 6 ) 2 , [Rh(tpy) 2 ](PF 6 ) 3 , [Ru(phen)(tpy)Cl](PF 6 ), [Rh(phen)(tpy)Cl](PF 6 ) 2 (phen = phenanthroline; tpy = S-[ω-(2,2:6′,2″-terpyridin-4′-yl)phenoxy]alkyl ethanethioate) have been described. Ligands and complexes were characterised by 1 H NMR spectroscopy, mass spectrometry, elemental analysis and cyclic voltammetry data. The crystal structure of the complex [Rh(phen)(tpy)Cl](PF 6 ) 2 (phen = phenanthroline; tpy = 4′-phenyl-2,2′:6′,2″-terpyridine) ( 21 ), have been determined by X-ray crystallography. Complex 21 show a distorted octahedral geometry around the ruthenium centre. Antimicrobial activity toward Escherichia coli at concentrations as low as 5 μM was found for some of the studied complexes. For complexes [Rh(tpy C 6 H 4 O(CH 2 ) 8 SCOCH 3 ) 2 ](PF 6 ) 3 ( 19 ), [Rh(phen)(tpy C 6 H 4 O (CH 2 ) 8 SCOCH 3 )Cl](PF 6 ) 2 ( 31 ) and [Rh(phen)(tpy C 6 H 4 O (CH 2 ) 11 SCOCH 3 )Cl](PF 6 ) 2 ( 32 ), a strong inhibition of in vitro protein synthesis was observed using firefly luciferase. An investigation of cytotoxicity of the complexes against human embryonic kidney cells (HEK293 line) by the MTT assay demonstrates that the toxicity of all tested compounds is of similar magnitude, with IC 50 values of 3–30 μM. [ABSTRACT FROM AUTHOR]

Prostate cancer is one of the most commonly diagnosed men's cancers and remains one of the leading causes of cancer death. The development of approaches to the treatment of this oncological disease is an ongoing process. In this work, we have carried out the selection of ligands for the creation of conjugates based on the drug docetaxel and synthesized a series of three docetaxel conjugates. In vitro cytotoxicity of these molecules was evaluated using the MTT assay. Based on the assay results, we selected the conjugate which showed cytotoxic potential close to unmodified docetaxel. At the same time, the molar solubility of the resulting compound increased up to 20 times in comparison with the drug itself. In vivo evaluation on 22Rv1 (PSMA+) xenograft model demonstrated a good potency of the synthesized conjugate to inhibit tumor growth: the inhibition turned out to be more than 80% at a dose of 30 mg/kg. Pharmacokinetic parameters of conjugate distribution were analyzed. Also, it was found that PSMA-targeted docetaxel conjugate is less toxic than docetaxel itself, the decrease of molar acute toxicity in comparison with free docetaxel was up to 20%. Obtained conjugate PSMA-DOC is a good candidate for further expanded preclinical trials because of high antitumor activity, fewer side toxic effects and better solubility. [Display omitted] • A series of three docetaxel PSMA-targeted conjugates were synthesized. • The most potent conjugate PSMA-DOC demonstrated IC 50 value 2.7 on 22Rv1 cell line. • Tumor growth inhibition on 22Rv1 xenografts was 87% at a PSMA-DOC dosage of 10 mg/kg. • PSMA-DOC conjugate demonstrated increased solubility and decreased general toxicity. • PSMA-DOC pharmacokinetics, subchonic and chronic toxicities were estimated. [ABSTRACT FROM AUTHOR]

Nitrosylsulfuric acid is shown to be a usable reagent for the synthesis of 5-chloroisoxazoles from readily available 1,1-di-chlorocyclopropanes via nitrosation–heterocyclization reaction. A cytotoxicity of some of the prepared 5-chloroisoxazoles towards MCF7, A549, HEK293T and VA13 cell lines was evaluated. [ABSTRACT FROM AUTHOR]

Focusing on the molecular docking results, a series of 3,4-diarylisoxazoles, analogues of Combretastatin A4, bearing various substituents at the fifth position of the isoxazole ring and pharmacophore groups bioisosteric to methoxy substituent at ring B, were synthesized in good yields and high regioselectivity. Depending on the substituent at C5, three approaches were chosen for the construction of isoxazole ring, including nitrosation of gem-dihalocyclopropanes, nitrile oxide synthesis, and difluoromethoxylation of isoxazolone to afford 5-haloisoxazoles, 5-unsubstituted isoxazoles, and 5-difluoromethoxyisoxazoles, respectively. Isoxazoles 43 and 45 showed selective cytotoxicity and antitubulin inhibition properties in vitro , with pharmacodynamic profiles closely related to that of CA-4. Both of them slow down tumor growth (66-74%) in mouse xenografts and slightly exceed in effectiveness Combretastatin A4-phosphate itself., Competing Interests: The authors declare no competing financial interest., (© 2024 American Chemical Society.)

In order to obtain antimicrobial compounds with improved properties, new conjugates comprising two different biologically active agents within a single chimeric molecule based on chloramphenicol (CHL) and a hydrophobic cation were synthesized and studied. Chloramphenicol amine (CAM), derived from the ribosome-targeting antibiotic CHL, and the plant isoquinoline alkaloid berberine (BER) are connected by alkyl linkers of different lengths in structures of these conjugates. Using competition binding, double reporter system, and toeprinting assays, we showed that synthesized CAM-Cn-BER compounds bound to the bacterial ribosome and inhibited protein synthesis like the parent CHL. The mechanism of action of CAM-C5-BER and CAM-C8-BER on the process of bacterial translations was similar to CHL. Experiments with bacteria demonstrated that CAM-Cn-BERs suppressed the growth of laboratory strains of CHL and macrolides-resistant bacteria. CAM-C8-BER acted against mycobacteria and more selectively inhibited the growth of Gram-positive bacteria than the parent CHL and the berberine derivative lacking the CAM moiety (CH 3 -C8-BER). Using a potential-sensitive fluorescent probe, we found that CAM-C8-BER significantly reduced the membrane potential in B. subtilis cells. Crystal violet assays were used to demonstrate the absence of induction of biofilm formation under the action of CAM-C8-BER on E. coli bacteria. Thus, we showed that CAM-C8-BER could act both on the ribosome and on the cell membrane of bacteria, with the alkylated berberine fragment of the compound making a significant contribution to the inhibitory effect on bacterial growth. Moreover, we showed that CAM-Cn-BERs did not inhibit eukaryotic translation in vitro and were non-toxic for eukaryotic cells.

G4-stabilizing ligands are now being considered as anticancer, antiviral and antibacterial agents. Phenoxazine is a promising scaffold for the development of G4 ligands. Here, we profiled two known phenoxazine-based nucleoside analogs and five new nucleoside and non-nucleoside derivatives against G4 targets from telomere repeats and the KIT promoter region. Leading new derivatives exhibited remarkably high G4-stabilizing effects (comparable or superior to the effects of the commonly used selective G4 ligands PDS and NMM) and selectivity toward G4s over duplex (superior to BRACO-19). All phenoxazine-based ligands inhibited cellular metabolic activity. The phenoxazine derivatives were particularly toxic for lung adenocarcinoma cells A549' and human liver cancer cells HepG2 (CC 50 of the nucleoside analogues in the nanomolar range), but also affected breast cancer cells MCF7, as well as immortalized fibroblasts VA13 and embryonic kidney cells HEK293t (CC 50 in the micromolar range). Importantly, the CC 50 values varied mostly in accordance with G4-binding affinities and G4-stabilizing effects, and the phenoxazine derivatives localized in the cell nuclei, which corroborates G4-mediated mechanisms of action., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.)

We report herein a Pt(IV) prodrug with metronidazole in axial positions Pt - Mnz . The nitroaromatic axial ligand was conjugated with a cisplatin scaffold to irreversibly reduce under hypoxic conditions, thereby retaining the Pt(IV) prodrug in the area of hypoxia. X-ray near-edge adsorption spectroscopy (XANES) on dried drug-preincubated tumor cell samples revealed a gradual release of cisplatin from the Pt-Mnz prodrug instead of rapid intracellular degradation. The ability of the prodrug to penetrate into three-dimensional (3D) spheroid cellular cultures was evaluated by a novel electrochemical assay via a platinum-coated carbon nanoelectrode, capable of single-cell measurements. Using a unique technique of electrochemical measurements in single tumor spheroids, we were able to both detect the real-time response of the axial ligand to hypoxia and establish the depth of penetration of the drug into the tumor model.

A series of new organic ligands (5 Z ,5 Z ')-2,2'-(alkane-α,ω-diyldiselenyl)-bis-5-(2-pyridylmethylene)-3,5-dihydro-4 H -imidazol-4-ones (L) consisting of two 5-(2-pyridylmethylene)-3,5-dihydro-4 H -imidazol-4-one units linked with polymethylene chains of various lengths ( n = 2-10, where n is the number of CH 2 units) have been synthesized. The reactions of these ligands with CuCl 2 ·2H 2 O and CuClO 4 ·6H 2 O gave Cu 2+ or Cu 1+ containing mono- and binuclear complexes with Cu 2 LCl x ( x = 2-4) or CuL(ClO 4 ) y ( y = 1, 2) composition. It was shown that the agents reducing Cu 2+ to Cu 1+ in the course of complex formation can be both a ligand and an organic solvent in which the reaction is carried out. This fundamentally distinguishes the selenium-containing ligands L from their previously described sulfur analogs, which by themselves are not capable of reducing Cu 2+ during complexation under the same conditions. A higher cytotoxicity and reasonable selectivity to cancer cell lines for synthesized complexes of selenium-containing ligands was shown; unlike sulfur analogs, ligands L themselves demonstrate a high cytotoxicity, comparable in some cases to the toxicity of copper-containing complexes., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The increase in multi-drug resistant pathogenic bacteria is making our current arsenal of clinically used antibiotics obsolete, highlighting the urgent need for new lead compounds with distinct target binding sites to avoid cross-resistance. Here we report that the aromatic polyketide antibiotic tetracenomycin (TcmX) is a potent inhibitor of protein synthesis, and does not induce DNA damage as previously thought. Despite the structural similarity to the well-known translation inhibitor tetracycline, we show that TcmX does not interact with the small ribosomal subunit, but rather binds to the large subunit, within the polypeptide exit tunnel. This previously unappreciated binding site is located adjacent to the macrolide-binding site, where TcmX stacks on the noncanonical basepair formed by U1782 and U2586 of the 23S ribosomal RNA. Although the binding site is distinct from the macrolide antibiotics, our results indicate that like macrolides, TcmX allows translation of short oligopeptides before further translation is blocked.

A series of 5-oxo-4H-pyrrolo[3,2-b]pyridine derivatives was identified as novel class of highly potent antibacterial agents during an extensive large-scale high-throughput screening (HTS) program utilizing a unique double-reporter system-pDualrep2. The construction of the reporter system allows us to perform visual inspection of the underlying mechanism of action due to two genes-Katushka2S and RFP-which encode the proteins with different imaging signatures. Antibacterial activity of the compounds was evaluated during the initial HTS round and subsequent rescreen procedure. The most active molecule demonstrated a MIC value of 3.35 µg/mL against E. coli with some signs of translation blockage (low Katushka2S signal) and no SOS response. The compound did not demonstrate cytotoxicity in standard cell viability assay. Subsequent structural morphing and follow-up synthesis may result in novel compounds with a meaningful antibacterial potency which can be reasonably regarded as an attractive starting point for further in vivo investigation and optimization.

The present report describes our efforts to identify new structural classes of compounds having promising antibacterial activity using previously published double-reporter system pDualrep2. This semi-automated high-throughput screening (HTS) platform has been applied to perform a large-scale screen of a diverse small-molecule compound library. We have selected a set of more than 125,000 molecules and evaluated them for their antibacterial activity. On the basis of HTS results, eight compounds containing 2-pyrazol-1-yl-thiazole scaffold exhibited moderate-to-high activity against ΔTolC Escherichia coli. Minimum inhibitory concentration (MIC) values for these molecules were in the range of 0.037-8 μg ml -1 . The most active compound 8 demonstrated high antibacterial potency (MIC = 0.037 μg ml -1 ), that significantly exceed that measured for erythromycin (MIC = 2.5 μg ml -1 ) and was comparable with the activity of levofloxacin (MIC = 0.016 μg ml -1 ). Unfortunately, this compound showed only moderate selectivity toward HEK293 eukaryotic cell line. On the contrary, compound 7 was less potent (MIC = 0.8 μg ml -1 ) but displayed only slight cytotoxicity. Thus, 2-pyrazol-1-yl-thiazoles can be considered as a valuable starting point for subsequent optimization and morphing.

A straightforward protocol toward pharmacologically relevant (het)areno[ x , y - b ]pyrrolo[1,2- d ][1,4]diazepines in good to high yields has been described. The designed approach consists of an acid-promoted furan ring opening in easily accessible N -(2-furylethyl)-2-nitroanilines or their heterocyclic analogues followed by the reductive cyclization of the corresponding nitro-1,4-diketones.

Multidrug-resistant tuberculosis (TB), extensively drug-resistant TB, and TB-human immunodeficiency virus (HIV) coinfection require a special approach in anti-TB treatment. Most patients cannot be successfully cured by conventional chemotherapy alone. They need a modern approach using minimally invasive therapeutic and surgical techniques. The novel approaches of collapse therapy techniques and minimally invasive osteoplastic thoracoplasty increase the effectiveness of complex anti-TB therapy. Achieving the required selective collapse of lung tissue in destructive pulmonary TB, especially in cases of drug resistance and/or HIV coinfection, leads to bacteriologic conversion, cavity closure, and successful cure., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Purpose: High- and medium-throughput assays are now routine methods for drug screening and toxicology investigations on mammalian cells. However, a simple and cost-effective analysis of cytotoxicity that can be carried out with commonly used laboratory equipment is still required., Procedures: The developed cytotoxicity assays are based on human cell lines stably expressing eGFP, tdTomato, mCherry, or Katushka2S fluorescent proteins. Red fluorescent proteins exhibit a higher signal-to-noise ratio, due to less interference by medium autofluorescence, in comparison to green fluorescent protein. Measurements have been performed on a fluorescence scanner, a plate fluorimeter, and a camera photodocumentation system., Results: For a 96-well plate assay, the sensitivity per well and the measurement duration were 250 cells and 15 min for the scanner, 500 cells and 2 min for the plate fluorimeter, and 1000 cells and less than 1 min for the camera detection. These sensitivities are similar to commonly used MTT (tetrazolium dye) assays. The used scanner and the camera had not been previously applied for cytotoxicity evaluation. An image processing scheme for the high-resolution scanner is proposed that significantly diminishes the number of control wells, even for a library containing fluorescent substances. The suggested cytotoxicity assay has been verified by measurements of the cytotoxicity of several well-known cytotoxic drugs and further applied to test a set of novel bacteriotoxic compounds in a medium-throughput format., Conclusion: The fluorescent signal of living cells is detected without disturbing them and adding any reagents, thus allowing to investigate time-dependent cytotoxicity effects on the same sample of cells. A fast, simple and cost-effective assay is suggested for cytotoxicity evaluation based on mammalian cells expressing fluorescent proteins and commonly used laboratory equipment.