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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]

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.)

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.