A Fluorescence Study on Binding Interaction of N-acetylated Dansylamide Conjugates with β-cyclodextrin, Tween-20 and DPPC Lipid Bilayer Membrane

The relationship between solvatochromic properties and in silico ADME parameters of new chloroethylnitrosourea derivatives with potential anticancer activity and their β-Cyclodextrin complexes

In view of the anticancer effect of nitrosoureas a set of four new N-(2-chloroethyl)-N-nitrosourea (CENU) derivatives was synthesized. An in silico absorption, distribution, metabolism, excretion and toxicity (ADME/Tox) prediction study revealed that the CENU derivatives satisfied all the required criteria for oral administration and introduced them as remarkable anticancer candidates in the central nervous system (CNS). A comparative solvatochromic study including the Kamlet-Taft, Catalán and Laurence models indicated that the solvatochromic behavior of the CENUs depended on both, unspecific and specific solvent-solute interactions. In detail, the solvatochromic effect of the solvent polarity on the absorption and emission maxima was significant for all CENUs, whereas the solvatochromic effect of the solvent's ability to donate or accept hydrogen bonds on the absorption and emission maxima was critically dependent on the electron density of the N'-aryl group. From the solvatochromic comparison method, excellent correlations (r ≥ 0.890) were obtained between the ADME parameters and the solvatochromic regression coefficients obtained by the Catalán model. As potential stabilizers, inclusion complexes of the investigated CENU derivatives with β-cyclodextrin (β-CD) were also explored. The spectrofluorimetric host-guest experiments included double-reciprocal Benesi-Hildebrand plots as well as the molar ratio and continuous variation plots (Job's plots), which established a 1:1 β-CD to CENU binding stoichiometry and relatively high affinities of β-CD for CENU derivatives.

Interaction of alkyl chain containing pyrene derivatives with different micellar media: Synthesis and photophysical study

The present work describes the synthesis and photophysical studies of four newly synthesized alkyl chain containing pyrene derivatives and their applications in micellization process of different types of surfactants e.g. CTAB and SDS. The fluorescent properties of these pyrene derivatives were utilized to understand the micellization process of CTAB and SDS. The length of alkyl chain affects the hydrophobicity of pyrene fluorophore which also affects the sensitivity of fluorophore towards the micellization of CTAB and SDS surfactants. The longest alkyl tail containing, PBBU showed more sensitivity whereas moderate alkyl chain containing, PABU and PBME showed moderate sensitivity and finally PAME contained smallest alkyl tail, showed no sensitivity towards the micellization of CTAB and SDS. The alkyl tail of fluorophore make it more hydrophobic and it could easily bind with the hydrophobic inner core of micelles. In both surfactants, PBBU showed LE emission at ~400 nm and aggregate emission at ~470 nm, whereas, PABU and PBME showed LE emission band at ~400 nm. Before CMC, the aggregates band of PBBU increased with increasing the surfactant concentrations, but after CMC the individual PBBU present into the water medium could binds with the inner core of micelles. Thus PBBU senses the formation of premicellar aggregates of CTAB and SDS. The LE emission of the fluorophore gradually increases while increasing the CTAB and SDS concentrations. The change in fluorescence emission of PABU, PBME and PBBU with increasing concentration of CTAB and SDS were used to calculate the CMC of CTAB and SDS surfactants.

Binding interaction of N-acetylated acridine conjugate with ct-DNA and β-cyclodextrin: Synthesis and photophysical studies

In the present work we are reporting the synthesis and binding interaction of a saturated fatty acid containing 9-aminoacridine derivative (AC-PA) with ct-DNA and β-cyclodextrin (β-CD). From Steady-state fluorescence experiments this newly synthesized 9-aminoacridine derivative, AC-PA, shows more efficient binding interaction with ct-DNA as compared to the 9-aminoacridine (AC). The extent of interaction of AC-PA and AC with ct-DNA was found out by calculating the fluorescence quenching by using Stern-Volmer quenching equation. The calculated quenching constants of AC-PA and AC are (4.5 ± 0.5) × 10³M^-1 (3.7 ± 0.5) × 10³M^-1 respectively. The mechanism of fluorescence quenching of AC-PA and AC, were understand by using Stern-Volmer plots as well as time-resolved fluorescence experiments. The fluorescence quenching of AC-PA and AC by ct-DNA are static in nature and take place by formation of ground state complexes. The binding mode between AC-PA and AC were understood by DNA melting analysis experiment. The DNA melting analysis experiments were reveals that the binding interactions between fluorophores (AC-PA and AC) with ct-DNA are intercalative in nature. The melting temperature and mode of binding intercalative mode of binding between AC-PA and AC were further confirmed by DSC and CD experiments. The steady-state and time-resolved fluorescence parameters of AC-PA are quite sensitive towards the formation of inclusion complexes between AC-PA and β-CD. Long hydrophobic tail containing acridine conjugate (AC-PA) shows more efficient binding interactions with the β-CD and the calculated binding constants value of AC-PA is 0.51 × 10²M^-1. Whereas, the parent molecule, AC not showing any binding interactions with β-CD.