Fluorescence Investigation of Interactions Between Novel Benzanthrone Dyes and Lysozyme Amyloid Fibrils

Synthesis and Properties of New 3-Heterylamino-Substituted 9-Nitrobenzanthrone Derivatives

In the present study, new fluorophores based on disubstituted benzanthrone derivatives were designed starting from 9-nitro-3-bromobenzanthrone with nucleophilic substitution of the bromine atom with some secondary cyclic amines. It has been found that this reaction is positively affected by the presence of a nitro group in comparison with 3-bromobenzanthrone. The new compounds exhibit intense absorption and pronounced luminescent properties in various organic solvents. In this regard, their photophysical properties were evaluated with an experimental study of the solvatochromic behavior of the obtained compounds in various solvents. It has recently been found that the addition of an electron-withdrawing nitro group to the benzanthrone core increases its first- and second-order hyperpolarizability. Such dyes can be used in the fabrication of optical limiter devices. Therefore, the developed fluorescent molecules have a potential prospect for extensive application in optoelectronics.

3-(Phenylethynyl)-7H-benzo[de]anthracen-7-one

The present work describes the facile synthesis of 3-(phenylethynyl)-7H-benzo[de]anthracen-7-one via a Sonogashira coupling reaction. The structure of the synthesized benzanthrone derivative is characterized by 1H- and 13C-NMR spectroscopy and high-resolution mass spectrometry. The photophysical properties of the title compound are investigated by means of UV-Vis and fluorescence spectroscopy in various organic solvents.

N′-(3-Bromo-7-oxo-7H-benzo[de]anthracen-9-yl)-N,N-dimethylimidoformamide

We report a synthesis of 3-bromo-9-N′-(N,N-dimethylformamidino)benzanthrone in good yield by a condensation reaction of 3-bromo-9-aminobenzanthrone with dimethylformamide in the presence of phosphorous oxychloride. The structure of the synthesized amidine was characterized by FTIR-ATR, NMR experiments, and elemental analysis. The title compound was analyzed by UV-Vis and fluorescence spectroscopy in various organic solvents.

Finding New Precursors for Light Harvesting Materials: A Computational Study of the Fluorescence Potential of Benzanthrone Dyes

Benzanthrone dyes are organic luminophores with excellent optoelectronic properties. This computational investigation is based on density functional theory and aims to explore the photophysical behavior of some of the reported aminobenzanthrones in addition to many unreported dyes containing different electron-donating substituents. Significant changes in the dipole moment and the overall structure of the dyes upon solvation in ethanol have been observed. We find that intramolecular charge transfer is more pronounced in the solvent medium, which facilitates the emission to shift bathochromically. Intersystem crossing is predicted to be absent, which makes relaxation of the molecule to ground state more efficient by emitting in the visible region.

Aggregation behavior of novel heptamethine cyanine dyes upon their binding to native and fibrillar lysozyme

Novel cyanine dyes can be used for amyloid fibril detection.

Fluorescence monitoring of the effect of oxidized lipids on the process of protein fibrillization

The kinetics of lysozyme and insulin amyloid formation in the presence of the oxidized phospholipids (oxPLs) was investigated using Thioflavin T fluorescence assay. The kinetic parameters of fibrillization process (lag time and apparent rate constant) have been determined upon varying the following experimental parameters: the type of lipid assemblies (premicellar aggregates and lipid bilayer vesicles), pH, temperature and lipid-to-protein molar ratio. It was found that oxPLs premicellar aggregates induced the more pronounced increase of the maximum Thioflavin T fluorescence, which is proportional to the extent of fibril formation, compared to the vesicles composed of the oxidized and unoxidized lipids. In contrast, the oxPLs, used as dispersions or included into vesicles, inhibited fibril nucleation and elongation under near-physiological conditions in vitro compared to liposomes containing unoxidized lipids. The results obtained provide deeper insight into the molecular mechanisms of the oxidative stress-modulated conformational diseases, and could be employed for the anti-amyloid drug development.

Novel benzanthrone probes for membrane and protein studies

The applicability of a series of novel benzanthrone dyes to monitoring the changes in physicochemical properties of lipid bilayer and to differentiating between the native and aggregated protein states has been evaluated. Based on the quantitative parameters of the dye-membrane and dye-protein binding derived from the fluorimetric titration data, the most prospective membrane probes and amyloid tracers have been selected from the group of examined compounds. Analysis of the red edge excitation shifts of the membrane- and amyloid-bound dyes provided information on the properties of benzanthrone binding sites within the lipid and protein matrixes. To understand how amyloid specificity of benzanthrones correlates with their structure, quantitative structure activity relationship (QSAR) analysis was performed involving a range of quantum chemical molecular descriptors. A statistically significant model was obtained for predicting the sensitivity of novel benzanthrone dyes to amyloid fibrils.