Vol. 57 No. 2 (261) (2023)

A method providing a high yield (80–94%) for producing gamma-hydroxy-butanoic acids hydrazides by the interaction of various representatives of cyclic esters with 85% hydrazine hydrate has been elaborated. It has been established that the introduction of a gamma-hydroxypropyl residue into the hydrazides composition results in new biological properties.

The inhibition of digestive enzyme trypsin by polyphenolic compounds derived from mountainous herbal infusions, as well as the effect of polarity and acidity of the media on this process were studied by virtue of UV-Vis absorption spectroscopy at 293.15 K. Mountainous herbal infusions (thyme, peppermint) are well known due to their biomedical significance and wide use as a beverage. The binding constant (K_b) and standard Gibbs energy change (ΔG⁰) were calculated. The obtained results show that polyphenols extracted from herbal infusions significantly inhibit trypsin. Moreover, the effect of thyme infusion is stronger compared with that of peppermint. The results show that the change of both polarity and H-bonding ability of polar organic cosolvent significantly alters the value of K_b, indicating that H-bonds and electrostatic interactions are the main driving forces in these interactions.

Inductively coupled plasma mass spectrometry (ISP-MS) and scanning electron microscope-X-ray fluorescence (SEM-XRF) methods were used for the investigation of olivine sorption properties. It has been shown, that olivine may be applied as a cheap and available material for the sorption of metals, including heavy metals, from wastewater. The comparatively low sorption capacity of olivine may pay off by its accessibility and cheapness. The mechanism of adsorption on the olivine surface may be described as the substitution of magnesium ions by cations of various metals. One trend can be fixed – when ionic radius of the metal cations increases, their sorption increases as well. However, it is hardly possible to tie everything with the ionic radius of metal ion. The specificity of each element is also important.

The work is devoted to a comparative study of the content of anthocyanins in the fruits of blueberries, blackberries and blackcurrants to develop a technological method for producing partially purified extracts. The latter, due to the significant content of anthocyanins, compounds with antioxidant, antiaggregate, angioprotective, anti-inflammatory activities stipulate their use in the complex therapy of ophthalmic diseases (myopia, age-related macular degeneration, diabetic retinopathy). The objects of the study were fresh natural fruits of common blueberries (Vaccinium myrtillus L.), blackberries (Rubus caesius L.) and blackcurrants (Ribes nigrum L.) collected in the foothill landscapes of the city of Aparan of the Republic of Armenia, harvested in 2022. The purpose of this study was to determine the comparative indicators of the quality and content of anthocyanins in fresh fruit extracts by direct spectrometry and obtain environmentally friendly extracts with the lowest content of macro- (Fe, Cu, Zn, Ca, Mg, etc.) and microelements (Mn, Co, Cd, V, Se, Cr, As, Pb, etc.) by ion-exchange sorption and desorption. It has been shown that the highest content of the total amount of anthocyanins in terms of cyanidin-3-O-glycoside is determined in the juice of fresh blueberries in an acidic medium at an analytical wavelength of 546 nm – 4.21 ± 0.18%. At the same time, the completeness of extraction of anthocyanins (≥ 95%) from blueberries is achieved at a ratio of raw material to extractant (95% EtOH, 1% HCl) 1 : 50 and when heated in a boiling water bath for 40 min. It has been shown that the content of these macro- and microelements in the extracts after ion-exchange sorption and desorption with Ku-2×8 (H⁺) cation exchanger does not exceed the permissible limits.

The enantiomers of the chiral compound (2S, 9S)-diamino-2,9-dibenzyldeca-4,6-diynedioic acid and (2R, 9R)-diamino-2,9-dibenzyldeca-4,6-diynedioic acid were separated by a chiral high-performance liquid chromatography (HPLC) method. The separation of α-amino acids was performed using a 5µ 4.0×250 mm column, which was obtained on the basis of a sorbent with eremomycin. The sorbent is silica gel (with 11 nm pore diameter and a surface area of 300 m²/g) with epoxy groups grafted on them with antibiotic eremomycin. Chiral HPLC is one of the most common methods for separating enantiomers of chiral compounds. Synthesis of new pharmaceutical substances, which are one of the isomers of a substance, obtaining of new drugs based on them, as well as the need to control the presence of the second isomer in such drugs, impose new requirements on the modern chromat-ographic separation of isomers.

In this work the effect of different temperatures on erythrocyte resistance has been studied. It was also examined the influence of various temperatures on optic density change of erythrocyte suspension. It was shown that there are no sharp changes of optic density values of erythrocyte suspension, based on which we assume that under the effect of the given temperatures the significant alterations are not observed, but the state of erythrocytes changes, particularly the structure of erythrocyte membranes changes. It was also revealed that the structural changes of erythrocyte membranes occur under the impact of environmental factors, including anthropogenic ones.

The study of the interaction of intercalators ethidium bromide (EtBr), methylene blue (MB) and groove binding compound Hoechst 33258 (H33258) with single-stranded synthetic polyribonucleotides poly(rA) and poly(rU) has been carried out by the method of UV-melting, at ionic strengths of the solution 0.04 M and 0.1 M. Stirring of poly(rA) and poly(rU) by equal-molar concentrations was shown to result in hybridization with formation of double-stranded (ds-) structure poly(rA)-poly(rU). It was revealed that EtBr, with higher degree in comparison with MB, stimulates hybridization and stabilizes the formed ds-structure poly(rA)-poly(rU). It was also found out that the hybridization process and affinity of EtBr and MB depend on the ionic strength of the solution and these processes occur much more effectively at the ionic strength 0.04 M. On the other hand, it was shown that the groove binding ligand H33258 practically does not affect the stabilization of the formed ds-structure poly(rA)-poly(rU).

The antitumor agent cisplatin and progesterone separate and joint action on content of total phospholipids and their individual fractions in nuclei from rat thymus cells were investigated. When used separately, cisplatin and progesterone exhibit its own distinctive properties. Cisplatin reduces, and progesterone, on the contrary, increases the content of total phospholipids. When used together, the effects of these drugs are summed up. Thus total phospholipid content of rat thymus cell nuclei increases by 17% after the joint injection of cisplatin and progesterone. These changes have different effects on quantities of individual phospholipid fractions. It is assumed that the effects of cisplatin and progesterone, both in their separate and joint action, can be mediated by quantitative changes in internuclear lipids that in turn can regulate the main functions of the cell nuclei.

Bioethanol production is in high demand due to its potential to replace transportation fuel and its ability to be renewable and long-lasting. Therefore, the bioconversion of fermentable sugars to ethanol is of central importance. The work aimed to explore yeast properties changes during fermentation at different pHs and temperature conditions. Biomass production, specific growth rate (SGR), fermentation products, and metabolite composition and quantity changes were studied at 25℃, 30℃, and 37℃ as well as pH 5 and pH 6.5 conditions. SGR data shows that at 25℃ and 30℃ pH 5 is optimal for yeast biomass production. At pH 5.0–6.5, the biomass production of the ATCC 9804 strain almost 2 times exceeds the same parameter for another strain. The highest biomass production was detected at 30℃ and pH 5. Ethanol production by yeast increases as the growth temperature decreases at pH 5 in contrast to pH 6.5, where the temperature changes within 30–37℃ range have no significant effect on it in both strains. At 30℃ ethanol concent­ra­tion in the extracellular medium reached ~117 mM in the case of ATCC 13007 strain, whereas for ATCC 9804 the same parameter was 1.4-fold lower. Both strains had the same substrate assimilation rate. Glycerol production reduces with increasing growth temperature and pH; the highest glycerol concentration (6.1 mM) was observed within 32 h growth of ATCC 9804 strain at 25℃, pH 5 and reaches 5.5 mM within 24 h growth of ATCC 13007 strain under the same conditions. At pH 5 and 6.5, the free energy for glycerol production was 2.3-fold and 4-fold higher compared to that of ethanol and acetate production processes in both strains. Gibbs free energy of ethanol production reaches the lowest value compared to the same parameter of acetate and glycerol production at pH 5, suggesting a preference for the alcoholic fermentation metabolic pathway under these conditions. The lowest acetate production was observed after 24 hours of growth of the ATCC 13007 strain at 37°C and pH 5, with ΔG = 173.9 kJ/mol. Obtained data highlights temperature stress mechanisms regulation of yeast and can be used for improving ethanol production processes and yeast genetic modification tools.

Glycine-betaine (GB) is an abundant organic material in soil, and the chemo­litho­autotrophic soil bacterium R. eutropha H16, one of the best bio-technological research models, may involve it in metabolism. The effect of different concentrations of GB (7–300 µmol/mL) on bacterial growth parameters and H₂-oxidizing activity of hydrogenases (Hyd) was studied. Stimulation of bacterial growth was registered at GB low concentrations, however, high concentrations have a partial inhibitory effect, in contrast to control (Fructose-Nitrogen medium). Upon GB supplemen­tation, the min and max H₂-oxidizing Hyd activity of R. eutropha whole cells were 3.4±0.01 U (g CDW)⁻¹ and 16.4±0.01 U (g CDW)⁻¹, respectively at concentrations of 7 µmol/mL and 300 µmol/mL, while it is absent in the control. These results might be used to develop new approaches to produce oxygen-tolerant Hyd.

Cyanobacteria generate biomass under photoautotrophic conditions during photosynthesis. Cultivation of cyanobacteria under photoheterotrophic conditions using various organic carbon sources can increase yield of biomass. In the current study, the effect of organic carbon sources on the growth properties and morphology of cyanobacteria Spirulina platensis, as well as the production of the photosynthetic pigments: chlorophyll a, carotenoids, and phycocyanin were investigated. Carbon sources, such as glucose, fructose and succinate, caused not only an increase in the cyanobacterial growth rate, but also morphological changes in S. platensis trichomes. An increase in the amounts of photosynthetic pigments was also observed. Thus, glucose, fructose, and succinate are more efficient substrates for photoheterotrophic cultivation of these cyanobacteria.

Quantitative parameters of total and fecal coliform, as well as Escherichia coli bacteria in the river waters of the Voghji River catchment basin were investigated to characterize fecal contamination in the investigated watershed basin. Water samples for microbial analyses were collected from the Voghji River and its Geghi, Norashenik and Vachagan tributaries in 2016, 2017 and 2020. The results of the study revealed the distribution, potential sources and environmental risks of fecal contamination in the Voghji River catchment basin.

The study of antioxidants in plants is one of the modern scientific and practical problems. The aim of this work is to obtain the extracts of pharmacy sale juniper berries and seeds, and to study their antioxidant properties by the method of competitive reactions. In this work, a number of extraction methods were used, and the investigation of the obtained extracts was performed by spectrometric and chromatographic methods.