Tetrahydroquinazoline N-oxide derivatives inhibit reproduction of tick-borne and mosquito-borne flaviviruses

Tick-borne encephalitis virus (TBEV), yellow fever virus (YFV), and West Nile virus (WNV) are flaviviruses causing emerging arthropod-borne infections of a great public health concern. Clinically approved drugs are not available to complement or replace the existing vaccines, which do not provide sufficient coverage. Thus, the discovery and characterization of new antiflaviviral chemotypes would advance studies in this field. In this study, a series of tetrahydroquinazoline N-oxides was synthesized, and the antiviral activity of the compounds was assessed against TBEV, YFV, and WNV using the plaque reduction assay along with the cytotoxicity to the corresponding cell lines (porcine embryo kidney and Vero). Most of the studied compounds were active against TBEV (EC₅₀  2 to 33 μM) and WNV (EC₅₀  0.15 to 34 μM) and a few also demonstrated inhibitory activity against YFV (EC₅₀  0.18 to 41 μM). To investigate the potential mechanism of action of the synthesized compounds, time-of-addition (TOA) experiments and virus yield reduction assays were performed for TBEV. The TOA studies suggested that the antiviral activity of the compounds should affect the early stages of the viral replication cycle after cell entry. Compounds with tetrahydroquinazoline N-oxide scaffold show a broad spectrum of activity against flaviviruses and represent a promising chemotype for antiviral drug discovery.

Novel Nanomolar Allosteric Modulators of AMPA Receptor of Bis(pyrimidine) Series: Synthesis, Biotesting and SAR Analysis

Positive allosteric modulators (PAMs) of AMPA receptors represent attractive candidates for the development of drugs for the treatment of cognitive and neurodegenerative disorders. Dimeric molecules have been reported to have an especially potent modulating effect, due to the U-shaped form of the AMPA receptor's allosteric binding site. In the present work, novel bis(pyrimidines) were studied as AMPA receptor modulators. A convenient and flexible preparative approach to bis(pyrimidines) containing a hydroquinone linker was elaborated, and a series of derivatives with varied substituents was obtained. The compounds were examined in the patch clamp experiments for their influence on the kainate-induced currents, and 10 of them were found to have potentiating properties. The best potency was found for 2-methyl-4-(4-((2-methyl-5,6,7,8-tetrahydroquinazolin-4-yl)oxy)phenoxy)-6,7,8,9-tetrahydro-5H-cyclohepta[d]pyrimidine, which potentiated the kainate-induced currents by up to 77% in all tested concentrations (10^-12-10^-6 M). The results were rationalized via the modeling of modulator complexes with the dimeric ligand binding domain of the GluA2 AMPA receptor, using molecular docking and molecular dynamics simulation. The prediction of ADMET, physicochemical, and PAINS properties of the studied bis(pyrimidines) confirmed that PAMs of this type may act as the potential lead compounds for the development of neuroprotective drugs.

Bivalent AMPA receptor positive allosteric modulators of the bis(pyrimidine) series

The first example of a novel class of AMPA receptor positive allosteric modulators of the bis(pyrimidine) series having a hydroquinone linker has been obtained and showed a potency to increase kainate-induced currents at subnanomolar concentrations.

Organochlorine pesticide and trace metal monitoring of Russian rivers flowing to the Arctic Ocean: 1990-1996

Information is presented on the concentrations of organochlorine pesticides (HCHs and DDT residues) and trace metals (Fe, Cu, Zn and Ni) in waters of 15 large Russian rivers flowing to the Arctic Ocean during 1990-1996. Estimates of the corresponding annual fluxes are made. Other contaminants (Hg, Pb, Cr, Mn, beta-HCH and dihydroheptachlor) were examined briefly. Concentration data are presented as averaged annual means for each of the seven years with the ranges, standard deviations and numbers of samples. Also given are data on locations, the methods of analysis and limited quality assurance data. Data on discharges to the Northern Seas for the more frequently monitored contaminants are given for rivers accounting for >70% of the total northerly flows. Scaled-up fluxes to account for unmonitored rivers as well are given for each sea; totals over the period were: Fe, 1452; Cu, 15; Zn, 59 (x 10(3) t yr(-1)); alpha-HCH, 25; gamma-HCH, 44 (t yr(-1)). Ni was monitored at too few rivers to estimate its total Russian flux. The fluxes for the HCHs considerably exceed previous estimates and indicate that the Arctic Ocean is not in balance as much as was previously believed.