Experimental and theoretical study of the spectral behavior of Trypan Blue in various solvents

Solubility and Preferential Solvation of Piroxicam in Neat Solvents and Binary Systems

The solubilization and solvatochromic behavior of piroxicam (PRX) were analyzed using UV-vis spectroscopy in neat (protic and aprotic) and binary solvent mixtures. The effects of solvent dipolarity/polarizability and solvent–solute hydrogen bonding interactions on the absorption maxima were evaluated by means of the linear solvation energy relationship concept of Kamlet and Taft. This analysis indicated that both interactions play an important role in the position of the absorption maxima in neat solvents. While, the PRX solubility depends on the solute–solvent specific interactions, polarizability and the cohesive forces of the solvent, manifested mainly by means of the Hildebrand’s solubility parameter. Preferential solvation (PS) was studied in 10 binary mixtures. A non-ideal behavior of the wavenumber curve as the function of analytical mole fraction of co-solvent was detected. Index of preferential solvation, as well as the influence of solvent parameters were calculated. The process of dissolution was analyzed in aqueous binary mixtures of ethanol, ethylene glycol and propylene glycol. They were not spontaneous in all proportions, but when water concentration decreases in the mixtures, the process becomes more spontaneous.

FRET-based method for evaluation of the efficiency of reversible and irreversible sonoporation

It is widely known that not all of the treated cells survive after introduction of exogenous molecules via any physical method. Therefore, it is important to develop methods that would allow simultaneous evaluation of both molecular delivery efficiency and cell viability. This study presents Förster resonance energy transfer (FRET)-based method that allows molecular transfer and cell viability evaluation in a single measurement by employing two common fluorescent dyes, namely, ethidium bromide and trypan blue. The method has been validated using cell sonoporation. The FRET-based method allows the efficiency evaluation of both reversible and irreversible sonoporation in a single experiment. Therefore, this method could be used to reduce time, labor, and material cost while improving the accuracy of evaluations.

Tomato cystine-knot miniproteins possessing anti-angiogenic activity exhibit in vitro gastrointestinal stability, intestinal absorption and resistance to food industrial processing

The cystine-knot miniproteins present in tomato fruit (TCMPs) have been shown to exert anti-angiogenic effects by inhibiting endothelial cell migration and to display resistance to gastrointestinal proteolytic attack. To better define the pharmacological potential of TCMPs, their oral bioavailability and their resistance to industrial processing must be assessed. To explore the intestinal transport of TCMPs we used the differentiated Caco-2 cells model. After 24h incubation, 37.73±9.34% of TCMPs crossed the epithelium, without altering the integrity of the cell layer. To assess the effects of the industrial processing on the biochemical features and the biological activity of TCMPs, we developed a method for purifying the proteins from tomato paste. The tomato-paste purified TCMPs retained the resistance to gastrointestinal digestion and the inhibitory activity towards endothelial cell migration. Our previous and present results collectively demonstrate that TCMPs possess interesting features for drug development.

Spectroscopic studies of keto–enol tautomeric equilibrium of azo dyes

Keto–enol tautomeric equilibrium of an azo dye is shifted to the keto form as the solvent polarity is increased.

A solvatochromic study of N-[4-(9-acridinylamino)-3-methoxyphenyl]methanesulfonamide hydrochloride: an experimental and theoretical approach

The effects of a solvent on the position of the long-wavelength electronic absorption band of N-[4-(9-acridinylamino)-3-methoxyphenyl]methanesulfonamide hydrochloride [m-AMSA.HCl], an antitumor drug, were investigated. To assess the nature of molecular interactions of protonated m-AMSA (1) with various organic solvents the solvatochromic shifts of absorption maxima (ν‾A) with (i) traditionally used bulk solvent polarity functions (Δf and F(ε, n)) and (ii) empirical scales of solvent polarity (Z, χB and ETN) were analyzed. Additionally, in order to investigate the influence of non-specific and specific solute-solvent interactions on absorption band shifts in protic solvents the multicomponent linear regression with two Kamlet-Taft's solvatochromic parameters (π* and α) was used. The ν‾A in solvents were also obtained using theoretical calculations with the AM1-SM5.4 method and compared with experimental values. Finally, all the results show that in aprotic solvents there are general dipolarity/polarizability effects, while in protic solvents specific interactions connected with the formation of hydrogen bonds are additionally observed.