An investigation of the membranotropic properties of the plant toxin thionin isolated fromPyrularia pubera

It has been shown by the ESR of spin probes that thionin initially interacts with with negatively charged membranes electrostatically and then passes into the membranes to a depth comparable with the length of the hydrophobic sections of the protein loops. Institute of Bioorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent. Brigham Young University, Provo, Utah, USA. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 594–597, July–August, 1993.     

Asymmetric oxidation of 4-nitro-6-trifluoromethyl-1,2,3-benzotrithiole

Both enantiomers of 4-nitro-6-trifluoromethyl-1,2,3-benzotrithiole 1-oxide as analogs of Varacins B and C were synthesized for the first time. The use of the Modena method ensures higher optical purity but lower yields of the chiral sulfoxides, as compared to the Kagan procedure.     

Complexation of lappaconitine with glycyrrhizic acid: stability and reactivity studies

NMR and UV-vis spectroscopy have been used to study the complexation of antiarrhythmic alkaloid lappaconitine with an efficient complexing agent from licorice, glycyrrhizic acid, which is known to profoundly influence the therapeutic activity of the alkaloid in the complex. In MeOH, DMSO, or aqueous solutions, lappaconitine has been shown to form a stable complex with glycyrrhizic acid with 1:1 stoichiometry over a broad concentration range from 1 microM to 300 microM. The stability constant K(11) equals 2.0 x 10(5) M(-1) in aqueous solution. A similar complex of lappaconitine hydrobromide--the pharmaceutical formulation used in the treatment of arrhythmia--is 2 orders of magnitude less stable than pure lappaconitine. A notable decrease in the rate of the photoinduced electron-transfer reaction between lappaconitine in a complex with glycyrrhizic acid and tyrosine allows the suggestion of an explicit interrelation between the suppressed chemical reactivity of the bound alkaloid and the changes of its therapeutic efficiency.     

Reactions of Some Terpenoids with CH-Acids in the Presence of Cs-β Zeolite

Reactions of some ,-unsaturated ketones from terpenoid series with CH-acids in the presence of Cs- zeolite were studied under various conditions. The variation of reaction conditions (heating, ultrasonic irradiation) strongly affected the reaction products ratio, and the effect was singular in each case and gave different results.     

First synthesis of p-mentha-1,8-diene triol

The first synthesis of p-mentha-1,8-diene triol from (?)-verbenone included obtaining pinane epoxy diol and its subsequent acid-catalyzed rearrangement on montmorillonite clay as the key steps.     

On inner dilatations of the mappings with unbounded characteristic

For the mappings f:D ? D￠,  D,  D￠ ì \mathbbRⁿ f:D \to D',\,\,D,\,\,D' \subset {\mathbb{R}^n} , n ≥ 2, satisfying certain geometric conditions in the fixed domain D, we have proved estimates of the form K _I (x, f) ≤ Q(x) almost everywhere, where K _I (x, f) is the inner dilatation of f at a point x, and Q(x) is a fixed real-valued function responsible for the “control” over a distortion of the families of curves in D at a mapping f.     

Triterpenic Acid Amides as Potential Inhibitors of the SARS-CoV-2 Main Protease

Although the incidence and mortality of SARS-CoV-2 infection has been declining during the pandemic, the problem related to designing novel antiviral drugs that could effectively resist viruses in the future remains relevant. As part of our continued search for chemical compounds that are capable of exerting an antiviral effect against the SARS-CoV-2 virus, we studied the ability of triterpenic acid amides to inhibit the SARS-CoV-2 main protease. Molecular modeling suggested that the compounds are able to bind to the active site of the main protease via non-covalent interactions. The FRET-based enzyme assay was used to reveal that compounds 1e and 1b can inhibit the SARS-CoV-2 main protease at micromolar concentrations.     

Assessing the Viability of Extended Nonmetal Atom Chains in MnF4n+2 (M=S and Se)

Theoretical investigations to evaluate the viability of extended nonmetal atom chains on the basis of molecular models with the general formula M_nF_4n+2 (M=S and Se) and corresponding solid‐state systems exhibiting direct S? S or Se? Se bonding were performed. The proposed high‐symmetry molecules were found to be minima on the potential energy surface for all S_nF_4n+2 systems studied (n=2–9) and for selenium analogues up to n=6. Phonon calculations of periodic structures confirmed the dynamic stability of the ‐(SF₄–SF₄)_∞‐ chain, whereas the analogous ‐(SeF₄–SeF₄)_∞‐ chain was found to have a number of imaginary phonon frequencies. Chemical bonding analysis of the dynamically stable ‐(SF₄–SF₄)_∞‐ structure revealed a multicenter character of the S? S and S? F bonds. A novel definition and abbreviation (ENAC) are proposed by analogy with extended metal atom chain (EMAC) complexes.