Bilirubin: Photophysical and photochemical properties, phototherapy, analytical methods of measurement. A short review.

Bilirubin, a yellow bile pigment, plays an important role in the body, being a potent antioxidant and having anti-inflammatory, immunomodulatory, cytoprotective, and neuroprotective functions. This makes bilirubin promising as a therapeutic and diagnostic agent in biomedicine. However, excess bilirubin is toxic and should be removed from the body.

Conjugates of amiridine and salicylic derivatives as promising multifunctional CNS agents for potential treatment of Alzheimer's disease.

New conjugates of amiridine and salicylic derivatives (salicylamide, salicylimine, and salicylamine) with different lengths of alkylene spacers were designed, synthesized, and evaluated as potential multifunctional central nervous system therapeutic agents for Alzheimer's disease (AD). Conjugates demonstrated high acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition (IC: AChE, 0.265-4.

Spectral-fluorescent study of substituted trimethine cyanine dyes in solutions and in complexes with DNA. Effects of aggregation, moderate heating, and decreasing pH.

Trimethine cyanine dyes are widely used as probes for the detection, study and quantification of biomolecules. In particular, cationic trimethine cyanines noncovalently interact with DNA with growing fluorescence. However, their use is often limited by the tendency to self-association - to the formation of aggregates.

Photonics of Some Monomethine Cyanine Dyes in Solutions and in Complexes with Biomolecules.

In search of new probes for biomolecules, the spectral fluorescent study of four monomethine cyanine dyes (MCD), both unsymmetrical and symmetrical, has been carried out in different organic solvents, in aqueous buffer solutions, and in the presence of DNA and HSA. The complexation of MCD with biomacromolecules leads to a steep growth of the fluorescence intensity. Complexes of MCD with dsDNA and HSA of various types were modeled in silico by molecular docking.

Photonics of Trimethine Cyanine Dyes as Probes for Biomolecules.

Cyanine dyes are widely used as fluorescent probes in biophysics and medical biochemistry due to their unique photophysical and photochemical properties (their photonics). This review is focused on a subclass of the most widespread and studied cyanine dyes-trimethine cyanines, which can serve as potential probes for biomolecules. The works devoted to the study of the noncovalent interaction of trimethine cyanine dyes with biomolecules and changing the properties of these dyes upon the interaction are reviewed.

Meso-aryl-substituted thiacarbocyanine dyes as spectral-fluorescent probes for DNA.

The noncovalent interaction of meso-aryl-substituted thiacarbocyanine dyes I and II with dsDNA and ssDNA in aqueous solutions has been studied by spectral-fluorescent methods. Complexation with DNA is accompanied by both aggregation of the dyes and the formation of monomeric strongly fluorescent complexes. Experiments on molecular docking of dyes I and II with dsDNA confirm the previous assumption about the possibility of the formation of complexes of different types: intercalation between base pairs and in the grooves of the double helix of the biopolymer.

Photonics of meso-substituted carbocyanine dyes in solutions and in complexes with DNA.

Spectral-fluorescent and photochemical properties (photoisomerization and generation of the triplet state) of meso-substituted cationic carbocyanine dyes, 3,3'-di-(β-hydroxyethyl)-5,5'-dimethoxy-9-ethylthiacarbocyanine iodide (K1) and 3,3'-di-(β-hydroxyethyl)-9-methylthiacarbocyanine iodide (K2), have been studied in solutions and in the presence of DNA. In solutions, on passing from acetonitrile to dioxane, a growth of fluorescence of the dyes is observed due to a shift of the equilibrium of cis/trans isomers toward the fluorescent trans-isomer. Upon flash photolysis of dye solutions in dioxane, the formation and subsequent decay of the cis-photoisomers of the dyes are observed.

Interaction between immunoglobulin G and peroxidase-like iron oxide nanoparticles: Physicochemical and structural features of the protein.

The study is devoted to the oxidative modification of immunoglobulin G (IgG) on the surface of peroxidase-like iron oxide magnetic nanoparticles (MNPs) under conditions of induced reactive oxygen species (ROS) generation and without them. A pronounced change of thermodynamic parameters of denaturation has been detected for IgG in solutions containing MNPs under hydrogen peroxide action during 24 h of incubation. Dynamic light scattering measurements and UV-Visible spectrophotometry have been used to show aggregation in these solutions.

Spectral-Fluorescent Study of the Interaction of Cationic and Anionic Polymethine Dyes with Sodium Deoxycholate in Aqueous Solutions.

The noncovalent interaction of a number of cationic and anionic meso-substituted polymethine (carbocyanine) dyes with sodium deoxycholate (NaDC) as a biologically important surfactant was studied by spectral-fluorescent methods. The following dyes were studied: 3,3'-di(β-hydroxyethyl)-9-methylthiacarbocyanine-iodide (K1), 3,3'-di(β-hydroxyethyl)-5,5'-dimethoxy-9-ethylthiacarbocyanine iodide (K2), 3,3',9-trimethylthiacarbocyanine iodide (K3, Cyan 2), 3,3'-di(γ-sulfopropyl)-9-methylthiacarbocyanine-betaine (A1), and 3,3'-di(γ-sulfopropyl)-4,5,4',5'-dibenzo-9-ethylthiacarbocyanine-betaine (A2, DEC). Upon addition of increasing concentrations of NaDC, the absorption spectra of dyes K1-K3 in aqueous solutions exhibit changes due to the formation of dye aggregates and their subsequent decomposition into monomers.

Spectral-fluorescent study of the interaction of polymethine dye probes with biological surfactants - bile salts.

Spectral-fluorescent properties of polymethine dye probes anionic 3,3'-di(sulfopropyl)-4,5,4',5'-dibenzo-9-ethylthiacarbocyanine-betaine (DEC) and cationic 3,3',9-trimethylthiacarbocyanine iodide (Cyan 2) in the presence of biological surfactants, bile salts sodium cholate (NaC), sodium deoxycholate (NaDC) and sodium taurocholate (NaTC), as well as sodium dodecyl sulfate (SDS), have been studied in a wide range of surfactant concentrations. When a surfactant is introduced into a solution of DEC, changes of the spectral-fluorescent properties are observed due to decomposition of dye dimers into cis-monomers and cis-trans conversion of the resulting monomers. In the presence of SDS, both processes occur in parallel, caused by noncovalent interaction of dye monomers with micelles, and mainly occur near the critical micelle concentration (CMC).

Influence of the interaction with DNA on the spectral-fluorescent and photochemical properties of some meso-substituted polymethine dyes.

Spectral-fluorescent and photochemical properties of meso-substituted thiacarbocyanine dyes 3,3'-dimethyl-9-phenylthiacarbocyanine and 3,3'-diethyl-9-(2-hydroxy-4-methoxyphenyl)thiacarbocyanine in solutions and their interaction with DNA were studied. The dyes form noncovalent complexes with DNA, which is accompanied by changes in the absorption spectra and an increase in the fluorescence intensity of the dyes. The data obtained suggest that the dyes are in the form of trans-isomers both in solvents of different polarity and in complexes with DNA.