Synthesis and study of spectral properties of amino acids-bodipy conjugates

© 2020, Ivanovo State University of Chemistry and Technology. The present work describes direct one-pot synthesis of the two novel amino acids-boron-dipyrromethene (BODIPY) conjugates with histidine and tyrosine residues bound to fluorophore via amino group. The synthesized compounds were fully characterized by means of 1H and 11B nuclear magnetic resonance spectroscopy, infrared spectroscopy, time-of-flight mass spectrome-try with matrix-activated laser desorption / ionization. All the data are in accordance with the proposed structures. The amino acids-BODIPY conjugates under study were investigated by means of absorbance and fluorescence spectroscopy. Absorption and emission spectra of the compounds in dimethyl sulfoxide (DMSO)-buffer solution (BS) mixture (1:1) were obtained. Moreover, a number of photophysical characteristics of the conjugates, namely: relative fluores-cence quantum yield, molar extinction coefficient, relative fluorescence lifetime, radiative and non-radiative rate constants were calulated. 3D fluorescence spectra of the compounds in DMSO-BS mixture (1:1) were obtained. Absorption and emission titration of the compounds was car-ried out. The results of the titration allowed us to confirm additionally a stoichiometric composi-tion of the conjugates. Quantum chemical analysis of structural and spectral properties of the compounds in a ground state was carried out. The results of quantum chemical calculations gave an insight to a nature of the BODIPY-amino acid interactions in the conjugates. Besides, the synthesized amino acids-BODIPY conjugates are found to be highly soluble in polar solvents. Thus, a range of unique properties of the objects of the present research enables us to use them for visualization of bioactive macromolecules as well as biochemical processes in living cells

Features of spatial structures of cyclosporins D, E and G revealed by NMR and MD simulations

Cyclosporins D, E and G were characterised by NMR spectroscopy, and backbone flexibility was studied by molecular dynamics simulation. Structures of the molecules were characterised by nuclear Overhauser effect spectroscopy, which revealed that the studied peptides have many common features. Molecular dynamics simulation showed that nanosecond dynamics of the backbone occurs in all cyclosporins, except CsE, which raised a question of how it can influence its biological activity

The spatial structure of macroheterocyclic compounds, as a key factor affecting the course of the macrocyclization reaction

© ISUCT Publishing. Nowadays the macrocyclization reaction is often used for the synthesis of new macroheterocyclic compounds. This is a one-pot reaction, carried out in one stage, which makes it the most convenient and efficient in the synthesis of complex macroheterocyclic compounds. One of the key parameters in the selection of synthesis conditions is the spatial structure and conformational composition of the synthesized compounds. The fact is that if the certain structure prevails in the solution, then it is the most energetically favorable, i.e. its potential energy is minimal and therefore it is necessary to spend less energy to synthesis of this compound. The structure, obtained during the synthesis process, largely depends on what solvent is used. In this work, it was shown that the conformational composition of the macroheterocyclic model compound in various solvents differs by 10-20 %. This fact must be taken into account when conducting macrocyclization reactions not only for the model compound presented in this paper, but also for other substances consisting of macroheterocyclic molecules, such as crown ethers, cyclosporine, calixarenes, and other classes of compounds having a non-rigid structure

La(III), Ce(III), Gd(III), and Eu(III) Complexation with Tris(hydroxymethyl)aminomethane in Aqueous Solution

© Lanthanides such as cerium(III), europium(III), and gadolinium(III) are widely used for designing fluorescent probes or magnetic resonance imaging contrasting agents for biological systems. The synthesis and study of lanthanide complexes in buffer solutions imitating biological fluids are often complicated because of a lack of data on the lanthanide interactions with buffer solution components. Therefore, Ln(III) [where Ln(III) = La(III), Ce(III), Gd(III), Eu(III)] complexation with a widely used buffer agent, tris(hydroxymethyl)aminomethane (Tris), in aqueous solution is studied using potentiometry, spectrofluorimetry, and 139La NMR spectroscopy. The stoichiometric composition of complexes is determined using mass spectrometry. The thermodynamic stability constants of Ln(III)-Tris complexes are calculated from potentiometric and spectral data; the difficulties in the study of these systems, reliability, and accuracy of the obtained constants are discussed. The possible structures of free Tris and its complexes with lanthanides(III) are optimized on the density functional theory/PBE0 level; the peculiarities of metal-ligand bonds were studied by Quantum Theory Atoms in Molecules analysis

Comparison of cyclosporin variants B–E based on their structural properties and activity in mitochondrial membranes

© 2020 Elsevier Inc. Cyclosporins B, C, D, and E were characterized by NMR spectroscopy, and backbone flexibility was studied by molecular dynamics simulation. Structures of the molecules were characterized by nuclear Overhauser effect spectroscopy, which revealed that the studied peptides have many common features. Molecular dynamics simulation showed that the backbone of cyclosporin E is relatively more rigid than in other peptides. Calcium-dependent swelling of liver mitochondria under the influence of four considered compounds was also investigated. Three of them were found to have the activity similar to cyclosporin A, inhibiting opening of the mitochondrial pore at concentrations within 100–300 nM. However, cyclosporin E did not show any biological effect at concentrations up to 1 μM. Results of this study agree with the idea on the correlation between the peptide chain flexibility and its bioavailability

Design, Spectral Characteristics, and Possibilities for Practical Application of BODIPY FL-Labeled Monoterpenoid

This article describes the design and biological properties of a BODIPY FL-labeled monoterpenoid BF2-meso-(4-((1″R)-6″,6″-dimethylbicyclo[3.1.1]hept-2″-ene-2″)yl-methoxycarbonylpropyl)-3,3′,5,5′-tetramethyl-2,2′-dipyrromethene conjugate (BODIPYmyrt). The fluorophore was characterized using X-ray, NMR, MS, and UV/vis spectroscopy. The conjugate exhibits a high quantum yield (to ∼100%) in the region 515-518 nm. BODIPYmyrt effectively penetrates the membranes of the bacterial and fungal cells and therefore can be used to examine the features of a broad spectrum of Gram-positive and Gram-negative bacteria and pathogenic fungi as well. Moreover, BODIPYmyrt exhibits a moderate tropism to the subcellular structures in mammalian cells (e.g., mitochondria), thereby providing an attractive scaffold for fluorophores to examine these particular organelles