Synthesis and study of complexes of the novel Russian antiviral drug Camphecene with pentacyclic triterpenes of licorice

For the first time, the complexation of pentacyclic triterpenes of licorice (glycyrrhizic acid (GA) and its aglycone, glycyrrhetinic acid (GLA)) with the novel Russian antiviral drug Camphecene (Camph) was investigated. The complexes obtained at different molar ratios were studied using both UV/Vis spectroscopy and mass spectrometry (ESI MS). Formation of the host:guest complexes were registered: GA and GLA molecular complexes (Camph+2GA; Camph+2GLA) with stability constants К = 6.94 106 М-2 and К = 2.89 106 М-2, respectively. The research results demonstrate a considerable potential of ESI MS as a technique for simple and fast detection of formation of the complexes of GA /GLA and the novel drugs

Study interaction of plants and fungi in drained bed of Aral sea in Kazakhstan

The purpose of this research was the study interaction of plans and fungi in the zone of weak salinization in the DBAS

Measuring the gap in ARPES experiments

Angle-resolved photoemission spectroscopy (ARPES) is considered as the only experimental tool from which the momentum distribution of both the superconducting and pseudo-gap can be quantitatively derived. The binding energy of the leading edge of the photoemission spectrum, usually called the leading edge gap (LEG), is the model-independent quantity which can be measured in the modern ARPES experiments with the very high accuracy--better than 1 meV. This, however, may be useless as long as the relation between the LEG and the real gap is unknown. We present a systematic study of the LEG as a function of a number of physical and experimental parameters. The absolute gap values which have been derived from the numerical simulation prove, for example that the nodal direction in the underdoped Bi-2212 in superconducting state is really the node--the gap is zero. The other consequences of the simulations are discussed.Comment: revtex4, 9 pages, 6 figure

Evaluation of Different Extraction Techniques for the Assay of Anti - Acetylcholinesterase Activity of Olive leaves (Olea europaea)

Received: 19.05.2021. Revised: 21.09.2021. Accepted: 08.11.2021. Available online: 09.11.2021.The total phenol content and the anti-acetylcholinesterase activity were compared in olive leaf (OL) extracts obtained using both subcritical water extraction (SbWE) and conventional solvent extraction (ethanol-water). The method proposed by Ellman (in vitro) was used to study the inhibitory activity of acetylcholinesterase (AChE). The total content of phenolic compounds and AChE activities of OL extracts varied depending on the used extraction method. Thus, the extract obtained using the subcritical water technique (220 °C) showed the highest amounts of total phenolic components, expressed as gallic acid equivalents, (70.4 mg/g raw material) and the highest inhibitory AChE-activity (IC50 = 0.35 mg/ml). The obtained values of the anti-AChE activity of the extracts of OL demonstrated that the inhibitory activity for SbW-extract 120 °C (IC50 = 2.92 mg/ml) and SbWextract 180 °C (IC50 = 0.8 mg/ml) is higher than that of the traditional extract (IC50 = 3.6 mg/ml), respectively. These results indicate a great potential of the subcritical water technique to develop the techniques to produce commercial extracts of OL, and these results could encourage improved utilization of the OL. The collected data on the anti - acetylcholinesterase activity of olive leaves clearly demonstrate the prospects for use of OL extracts in the development of novel pharmaceutical substances and nutraceuticals for the prevention and/or the treatment of Alzheimer's disease as well as some other neurodegenerative diseases.This work was supported by the Ministry of Science and Higher Education of the Russian Federation (State assignment in the field of scientific activity, project No 0852-2020-0031) and the Russian Foundation for Basic Research (RFBR, grant no. 19-33-90211-Aspiranty (S. S. Khizrieva))

Synthesis and study of complexes of the novel Russian antiviral drug Camphecene with Plant’s Flavonoids

Received: 01.03.2021. Revised: 22.04.2021. Accepted: 27.04.2021. Available online: 28.04.2021.The authors are grateful to the Corresponding Member of the RAS, Doctor of Chemical Sciences, Professor of NIOCH SB RAS Salakhutdinov N.F. for the kindly provided scaffold monoterpenoid Camphecene.Traditionally, glycyrrhizic acid has been used to form polydentate complexes. For the first time in the presented paper, the complexation of the Plant’s Flavonoids (Quercetin (Qu) and its glycoside - Rutin (Rut)) with the novel Russian antiviral drug Camphecene (Camph) was investigated. The complexes obtained at different molar ratios were studied using UV/Vis spectroscopy. Formation of the host: guest complexes were registered: Qu and Rut molecular complexes (Camph+2Qu; Camph+2Rut) with a stability constant K = 3.3·108 M-2. Comparison of the binding constants of the obtained complexes shows that the efficiency of Camphecene complexation with the participation of flavonoids is more efficient than with the participation of triterpenoids. Besides, it was found that the complexes of Camphecene with the quercetin and rutin are soluble in water, in contrast to the complexes with triterpenoids, which makes it possible to increase the bioavailability of both Camphecene and flavonoids. The obtained results demonstrate the high potential of flavonoids Qu and Rut to the development of novel pharmaceutical forms using the example of Camphecene in the form of molecular complexes, as the novel forms of delivery.This work was supported by the Ministry of Science and Higher Education of the Russian Federation (State assignment in the field of scientific activity, project No 0852-2020-0031) and the Russian Foundation for Basic Research (RFBR, grant no. 19-33-90211-Aspiranty)

High-temperature superconductivity from fine-tuning of Fermi-surface singularities in iron oxypnictides

In the family of the iron-based superconductors, the $RE$FeAsO-type compounds (with $RE$ being a rare-earth metal) exhibit the highest bulk superconducting transition temperatures ($T_{\mathrm{c}}$) up to $55\ \textrm{K}$ and thus hold the key to the elusive pairing mechanism. Recently, it has been demonstrated that the intrinsic electronic structure of SmFe$_{0.92}$Co$_{0.08}$AsO ($T_{\mathrm{c}}=18\ \textrm{K}$) is highly nontrivial and consists of multiple band-edge singularities in close proximity to the Fermi level. However, it remains unclear whether these singularities are generic to the $RE$FeAsO-type materials and if so, whether their exact topology is responsible for the aforementioned record $T_{\mathrm{c}}$. In this work, we use angle-resolved photoemission spectroscopy (ARPES) to investigate the inherent electronic structure of the NdFeAsO$_{0.6}$F$_{0.4}$ compound with a twice higher $T_{\mathrm{c}}=38\ \textrm{K}$. We find a similarly singular Fermi surface and further demonstrate that the dramatic enhancement of superconductivity in this compound correlates closely with the fine-tuning of one of the band-edge singularities to within a fraction of the superconducting energy gap $\Delta$ below the Fermi level. Our results provide compelling evidence that the band-structure singularities near the Fermi level in the iron-based superconductors must be explicitly accounted for in any attempt to understand the mechanism of superconducting pairing in these materials.Comment: Open access article available online at http://www.nature.com/articles/srep1827