Synthesis, Photophysical Properties and Antioxidant Activity of Novel Quinoline Derivatives.

Novel quinoline derivatives were synthesized based on 6-amino-substituted quinoline, and antioxidant activity of these compounds is studied by p-nitroso-N,N-dimethylaniline assay. The rate of the reaction between OH radicals and quinoline derivatives is determined by photometric method and the obtained results are compared with that of well-known antioxidant vitamin C. Quinoline derivatives exhibit pronounced antioxidant activity, which strongly depends on the structural features of compounds.

The Study of the Effect of Dimethylsulfoxide (or Diethylsulfoxide) on Quinine Sulfate-DNA Binding by UV-Vis and Steady-State Fluorescence Spectroscopies.

The effect of dimethylsulfoxide (DMSO) and diethylsulfoxide (DESO) on binding between quinine sulfate (QS) and DNA was studied by virtue of UV-Vis absorption, steady-state fluorescence spectroscopies, and fluorescence polarization measurements. The binding constant was determined at three different temperatures and the values of standard Gibbs energy change, enthalpy and entropy of binding were determined. The mechanism of binding and the effect of sulfoxides on this process was revealed.

Fluorescence anisotropy studies on the Hoechst 33258-DNA interaction: the solvent effect.

Fluorescence anisotropy method was applied to characterize the interactions of DNA minor groove binder Hoechst 33258 with different solvents without and in the presence of DNA. It is important to study the interaction of small molecules with DNA for the purpose of better understanding the mechanism of their action, as well as to design novel and more effective compounds. Spectroscopic study of the ligand in different binary mixed solvents containing DMSO, alcohols and buffer was carried out.

Study of the Interaction of Novel Nonprotein Amino Acids with Trypsin by Steady-State Fluorescence Spectroscopy.

The interaction of (2R, 3S)-hydroxyleucine (trypsin inhibitor) and β-hydroxyvaline with trypsin has been studied by the steady-state fluorescence spectroscopy. The analysis of fluorescence spectra has revealed the mechanism of binding of these nonprotein amino acids to trypsin. According to the docking (2R, 3S)-hydroxyleucine form hydrogen bonds with trypsin having little effect on tryptophan and tyrosine residues in enzyme molecule.

Photophysical properties of methylene blue in water and in aqueous solutions of dimethylsulfoxide.

A detailed study of the effect of aprotic polar solvents such as dimethylsulfoxide on methylene blue (MB) was carried out through a combination of UV-vis absorption and steady-state fluorescence spectroscopy techniques at 293.15 K. In aqueous solutions MB tends to exhibit strong tendency to aggregate.

The effect of dimethylsulfoxide on absorption and fluorescence spectra of aqueous solutions of acridine orange base.

The photophysical properties of aqueous solutions of acridine orange base (AOB) in wide concentration range of dimethylsulfoxide (DMSO) were studied by using absorption and steady-state fluorescence spectroscopy techniques at room temperature. The absorption spectrum of acridine orange in water shows two bands at 468 and 490 nm which were attributed to the dimer ((AOBH)2(2+)) and monomer (AOBH(+)) species respectively. In DMSO solution for the same AOB concentration only the basic form was detected with the band at 428 nm.