579 research outputs found
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
Magnetic anisotropy in strained manganite films and bicrystal junctions
Transport and magnetic properties of LSMO manganite thin films and bicrystal
junctions were investigated. Manganite films were epitaxially grown on STO,
LAO, NGO and LSAT substrates and their magnetic anisotropy were determined by
two techniques of magnetic resonance spectroscopy. Compare with cubic
substrates a small (about 0.3 persentage), the anisotropy of the orthorhombic
NGO substrate leads to a uniaxial anisotropy of the magnetic properties of the
films in the plane of the substrate. Samples with different tilt of
crystallographic basal planes of manganite as well as bicrystal junctions with
rotation of the crystallographic axes (RB - junction) and with tilting of basal
planes (TB - junction) were investigated. It was found that on vicinal NGO
substrates the value of magnetic anisotropy could be varied by changing the
substrate inclination angle from 0 to 25 degrees. Measurement of magnetic
anisotropy of manganite bicrystal junction demonstrated the presence of two
ferromagnetically ordered spin subsystems for both types of bicrystal
boundaries RB and TB. The magnitude of the magnetoresistance for TB - junctions
increased with decreasing temperature and with the misorientation angle even
misorientation of easy axes in the parts of junction does not change. Analysis
of the voltage dependencies of bicrystal junction conductivity show that the
low value of the magnetoresistance for the LSMO bicrystal junctions can be
caused by two scattering mechanisms with the spin- flip of spin - polarized
carriers due to the strong electron - electron interactions in a disordered
layer at the bicrystal boundary at low temperatures and the spin-flip by anti
ferromagnetic magnons at high temperatures.Comment: 26 pages, 10 figure
High-temperature superconductivity from fine-tuning of Fermi-surface singularities in iron oxypnictides
In the family of the iron-based superconductors, the FeAsO-type compounds
(with being a rare-earth metal) exhibit the highest bulk superconducting
transition temperatures () up to and thus hold
the key to the elusive pairing mechanism. Recently, it has been demonstrated
that the intrinsic electronic structure of SmFeCoAsO
() 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 FeAsO-type
materials and if so, whether their exact topology is responsible for the
aforementioned record . In this work, we use angle-resolved
photoemission spectroscopy (ARPES) to investigate the inherent electronic
structure of the NdFeAsOF compound with a twice higher
. 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
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
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)
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))
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