Confinement of 4,4-diaminodiphenyl sulfone by γ -CD in micellar environment: a spectroscopic investigation.

This paper reports the double confinement of 4,4-diaminodiphenyl sulfone (Dapsone) inside γ-cyclodextrin (CD) in presence of surfactants (cationic, anionic and nonionic) using steady-state and time-resolved fluorescence spectroscopy. Interpretation of fluorescence spectra, fluorescence anisotropy and time resolved fluorescence decay of the γ-CD • Dapsone•micellar system hints at lesser microviscosity and the partial release of the probe molecule from the supramolecular host-guest complex in ionic micelles, of which greater in cationic micelles, but due to greater restriction and rigidity in presence of non-ionic micelle makes the probe more rigidly inside CD. Changes in computed rotational decay also corroborate the above findings.

Spectral signature of 2-[4-(dimethylamino)styryl]-1-methylquinolinium iodide: a case of negative solvatochromism in water.

Photophysics of the 2-[4-(dimethylamino) styryl]-1-methylquinolinium iodide (DASQMI) molecule has been studied in different solvents by steady-state and time-resolved emission spectroscopy and also with quantum chemical calculations. The probe molecule exhibits a strong solvent-polarity-dependent characteristic. The low-energy fluorescence band of DASQMI shows an anomalous 40 nm blue shift in water from that in dimethyl sulfoxide (DMSO); though in deuterium oxide the normal trend of red shift was observed.

Reverse micelle induced flipping of binding site and efficiency of albumin protein with an ionic styryl dye.

The effect of reverse micelle environment on the binding mechanism of 2-(4-(dimethylamino)styryl)-1-methylpyridinium iodide (DASPMI) with Bovine Serum Albumin (BSA) compared with that in buffer solution has been investigated in this paper with the help of steady state and time-resolved emission spectroscopy along with molecular docking to have a correct picture about binding. The binding of DASPMI with attachment efficiency of 30% and 70% at site I (subdomain IIA) and site II (subdomain IIIA) of BSA, respectively, in buffer solution gets reversed inside a reverse micelle. The bigger cavity size of site II in buffer solution ushers the dye with increased attachment efficiency and in reverse micelle change in pi-stacking and hydrophobic interaction control the attachment efficiency.

Quest for mode of binding of 2-(4-(dimethylamino)styryl)-1-methylpyridinium iodide with calf thymus DNA.

The mode of binding of 2-(4-(dimethylamino)styryl)-1-methylpyridinium iodide (DASPMI) with calf thymus DNA as revealed from different steady state and time-resolved emission spectroscopic measurements has been reported in this paper. Fluorescence enhancement of DASPMI and its quenching by potassium iodide (KI) points to groove binding of dye with ct-DNA, rather than intercalation in the ct-DNA helix. An increase in steady state anisotropy and fluorescence lifetime hints at binding with ct-DNA.

On the spectral behavior of an ionic styryl dye: effect of micelle-polyethylene-block-polyethylene glycol diblock copolymer assembly.

The interaction of anionic micelle sodium dodecyl sulfate (SDS) and amphiphilic block copolymers polyethylene-b-polyethylene glycol (PE-b-PEG) and the sharp change of excited-state charge-transfer complex photophysics of 2-(4-(dimethylamino)styryl)-1-methylpyridinium iodide (DASPMI) inside of the supramolecular assembly have been addressed in the paper. The dramatic enhancement of emission intensity of DASPMI incorporated inside of the nanostructure formed by micellar and polymeric chains indicates a completely different environment compared to that in the water and micellar system. A huge increase in the rotational relaxation time obtained from time-resolved anisotropy decay and the value of the order parameter is indicative of a very restrictive regime in the self-assembly system.

QSAR of adenosine A3 receptor antagonist 1,2,4-triazolo[4,3-a]quinoxalin-1-one derivatives using chemometric tools.

Considering the potential of selective adenosine A3 receptor subtype ligands in the development of prospective therapeutic agents, an attempt has been made to explore physicochemical requirements of 1,2,4-triazolo[4,3-a]quinoxalin-1-one derivatives for A3 receptor binding. In this study, lipophilicity (logP), physicochemical substituent constants (pi, MR, sigma p) of phenyl ring substituents, and Wang-Ford charges of common atoms of the quinoxaline nucleus (calculated from molecular electrostatic potential surface of energy-minimized geometry using AM1 technique) were used as independent variables along with suitable dummy parameters. The best multiple linear regression (MLR) equation obtained from factor analysis (FA-MLR) as the preprocessing step could explain and predict 72.

Exploring 3D-QSAR of thiazole and thiadiazole derivatives as potent and selective human adenosine A3 receptor antagonists+.

Binding affinity data [Bioorg Med Chem (2004) 12:613-623] of thiazole and thiadiazole derivatives (n = 30) for the human adenosine A3 receptor subtype have been subjected to 3D-QSAR (Quantitative structure-activity relationships) analyses by molecular shape analysis (MSA) and molecular field analysis (MFA) techniques using Cerius2 Version 4.8. In the case of the MSA, the major steps were (1) generation of conformers and energy minimization; (2) hypothesizing an active conformer (global minimum of the most active compound); (3) selecting a candidate shape-reference compound (based on the active conformation); (4) performing pairwise molecular superimposition using the maximum common subgroup (MCSG) method; (5) measuring molecular shape commonality using MSA descriptors; (6) determining other molecular features by calculating spatial, electronic and conformational parameters; (7) selection of conformers; (8) generation of QSAR equations by genetic function algorithm (GFA) or stepwise regression.

Exploring QSAR of thiazole and thiadiazole derivatives as potent and selective human adenosine A3 receptor antagonists using FA and GFA techniques.

Binding affinity data of thiazole and thiadiazole derivatives (n=30) for human adenosine A3 receptor subtype have been subjected to Quantitative Structure-Activity Relationship (QSAR) analysis using quantum chemical and hydrophobicity parameters. Wang-Ford charges of the common atoms of the compounds [calculated from molecular electrostatic potential surface of energy minimized geometry using Austin Model 1 (AM1) technique] were used as independent variables apart from partition coefficient (logP) and suitable dummy parameters. The variables for the multiple regression analyses were selected based on principal component factor analysis (FA), and generated equations were statistically validated using leave-one-out technique.