Vol. 55 No. 2 (255) (2021)

Based on carbonyl derivatives of 4-substituted-4-butanolides, the appropriate semi- and thiosemicarbazones have been synthesized. It has been found that some representatives of thiosemicarbazones have pronounced algicidal activity against filamentous green alga Cladophora and blue-green alga (cyanobacterium) Synechocystis and some of the semi- and thiosemicarbazones exhibit moderate antitumor activity. The assessment of the antitumor activity of the compounds was carried out using strains of syngeneic and allogeneic tumor systems as test-objects: lymphocytic leukemia P-388, Lewis lung carcinoma, B16 melanoma and Ehrlich’s ascites tumor. It has also been established that some representatives of thiosemi­carbazones exhibit antimutagenic properties. It has been reliably proven that with the formation of a thiazole ring, all properties disappear and a new property in the series of thiazololactones is revealed – antibacterial․

Fluorescence properties of 4-hydroxy-2-methylquinoline (1) and 2-(5-mercapto-1,3,4-oxadiazol-2-yl)-6-methylquinoline-4-ol (2) were studied in dimethylsulfoxide (DMSO) aqueous solutions. The fluorescence properties of 1 and 2 exhibit substantial dependence on the DMSO concentration. The fluorescence quantum yield $(\Phi_f)$ of 1 decreases upon adding DMSO due to the shift in the keto-enol (E) tautomeric equilibrium toward E form․ On the contrary 2 demonstrates a tendency of increase of $\Phi_f$ upon adding DMSO due to intermolecular charge transfer from DMSO to the aromatic ring of quinoline, which increases the electron density on the ring and hence the fluorescence efficiency.

The formation of Ni²⁺:Tryptophan (Trp) 1:1 complex, which acts as a model catalyst for decomposition of cumene hydroperoxide (ROOH) in Ni²⁺+Trp+ROOH+H₂O system, has been confirmed via kinetic study in aqueous solution at pH>7. The kinetic expression of a single catalytic decomposition reaction of ROOH under the influence of [NiTrp]⁺ complex was brought out. The temperature dependence of the effective rate constant of ROOH decay (K_eff=K_cat[Ni²⁺]₀[Trp]₀=const) in the temperature range from 323 to 343 K can be expressed by Arrhenius equation (E_eff is in kJ/mol):  K_eff=(1.87±0.02)·10⁶exp[–(49.8±0.3)/RT], min ^–1.

The sorption properties of organomineral composite sorbents have been investigated by ICP-MS method. The diatomite of the Jradzor deposit and bentonite of the Sarigyuh deposit (Armenia) were used as inorganic constituents. Diatomite serves as a structure-forming component and provides mass transfer due to its high porosity (V = 2.0 cm³/g) and large pore sizes (150–200 nm). Bentonite is responsible for the functionality of the sorbents. The organic component is also responsible for the functionality of the obtained sorbents. Paper pretreated with acids (nitric and phosphoric) was used as an organic component. A synthetic solution containing cations of heavy metals was used as an object of study. The experiments were carried out in static mode on a Jar-Test device.

In this work the effect of millimeter range electromagnetic waves (MM EMW) with the frequency 64.5 GHz on the complexes of Hoechst 33258 (H33258) with DNA and human serum albumin (HSA) has been studied by the methods of absorption and fluorescence spectroscopies. It was shown that the irradiation results in weakening of H33258 interaction with both macromolecules, which is connected with the fact that the frequency 64.5 GHz, being resonant for water, leads to the structurizing of water component around DNA and HSA, due to which the binding becomes weaker. This conclusion is based on the values of both binding constants and Stern–Volmer constants.

Study on the interaction of DNA-specific ligands – classical intercalator acridine orange (AO) and groove binding compound Hoechst 33258 (H33258) with poly(rA)-poly(rU), being a model for double-stranded (ds-) RNA, has been carried out. The absorption and fluorescence spectra of the complexes of these ligands with ds-polynucleotide were obtained. It was revealed that the optic and fluorescent characteristics of the complexes of both ligands with ds-RNA are similar with those at the complex-formation with DNA.

The interaction of methylene blue (MB) and acridine orange (AO) with poly(rA)-poly(rU) was studied using absorption and fluorescence spectroscopy methods. The absorption and fluorescence spectra of complexes of these ligands with a polynucleotide were obtained, similar to those of complexes of these ligands with double-stranded (ds-) DNA. It was revealed that the isosbestic point in the spectra of the AO-poly(rA)-poly(rU) and MB-poly(rA)-poly(rU) complexes is not formed, although the binding of AO and MB with ds-RNA by intercalation mode is not excluded.

The study on the interaction of DNA-specific low-molecular compounds – groove binding material Hoechst 33258 and intercalating ligand methylene blue (MB) with serum albumin has been carried out. The absorption and differential absorption spectra of complexes of the mentioned ligands with protein were obtained. Changes of the absorption and differential absorption spectra indicate the binding of two ligands with albumin. The obtained results indicate that at the interaction with both ligands, the conformational state of the protein alters, though these changes are not similar, since in the case of MB a compactization of the protein folding occurs, while in the case of Hoechst 33258, most apparently, an unfolding of the compact structure takes place as a result of partial loss of helicity of $\alpha$-structures.

The study of the effect of different doses of $\gamma$-irradiation on the growth and development of seedlings of soft wheat seeds, resistance, and germination of seeds to irradiation has been carried out. The data show that the seeds of common wheat are resistant to ionizing radiation and up to 80% of the seeds remained viable. Under the influence of ionizing radiation, the functional and mitotic activity of the cell nucleus is disrupted, which has a significant effect on the growth parameters of the seedlings of irradiated seeds.

In this work we studied the effect of microscopic soil fungi on some lather samples. The species composition of micromycetes inhabiting the samples under study was revealed, and an assessment of the fungal resistance of the materials under study was given. In the process of work, species of microscopic soil fungi were isolated and identified from the soil. In order to determine the degree of resistance to fungi for the infection of samples, a water-spore suspension was obtained. The leather materials were partially destroyed by microscopic fungi, and mold resistance ranged from 2 to 3 on a 5-point scale.

West Nile virus disease is an emerging infectious vector borne disease. Of registered invasive species of mosquitoes in Armenia, Culex pipiens is the most implicated one in the potential transmission of West Nile virus (WNV). In previous years (1985–1999), research on circulation of mosquito-borne arboviruses in Armenia was conducted by the research Institute of Epidemiology and WNV, Batai, Sindbis, Tahyna and Gheta were found in mosquitoes. The only mosquito-borne disease historically registered in Armenia was malaria, without autochtonous cases since 2006. However, per retrospective medical chart review study (2016–2019) in the Nork Infection Clinical Hospital, about 30% of febrile patients is diagnosed as “Fever of Unknown Origin”. We hypothesize that these arboviruses are circulating in Armenia and largely mis-diagnosed and/or under reported. Based on the geographical locations of mosquitoes, the MaxEnt model with 19 bioclimatic variables was developed to predict future ecological niche of C. pipiens and potential high-risk areas for West Nile virus disease. It is the first step for the implementation of a statistically rigorous system for real-time alert of biorisk.

The results of the study have shown that when exposed to vibration, changes in cardiac activity occur in rabbits, the nature and direction of which depend on the parameters of the dynamic factor. Vibration with a frequency of 20 Hz causes moderate tachycardia, and 40 and 80 Hz – severe tachycardia. Three months of vibration in the first month of exposure causes tachycardia, and after three months of exposure, bradycardia. There is also a reduction in respiratory movements and a decrease in the activity of the enzyme succinate dehydrogenase.

The content of selenium organic forms in Astragalus and Thyme officinal plants was determined by means of spectrophotometry method using phenylthiourea as a reagent. The selenium content estimated spectrophotometrically is equal to: 11750 μg/kg in Astragalus and 450 μg/kg in Thyme. The amount of selenium in these plants determined earlier by means of mass-spectrometry method is equal to 12000 μg/kg and 600 μg/kg, respectively.