Modulation of the interaction of Coumarin 7 with DNA by β-cyclodextrin

• Published in: Journal of inclusion phenomena and macrocyclic chemistry Vol. 81; no. 1-2; pp. 225 - 236
• Main Authors: Chandrasekaran, Sowrirjan, Sameena, Yousuf, Enoch, Israel V. M. V.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.02.2015
• Subjects: Chemistry; Chemistry and Materials Science; Crystallography and Scattering Methods; Food Science; Organic Chemistry; Original Article; Fluorescence spectroscopy; Coumarin 7; Excited state pK; β-cyclodextrin; 2D ROESY
• ISSN: 1388-3127; 1573-1111
• DOI: 10.1007/s10847-014-0451-1

The possible structure of the host–guest complex, Coumarin 7/β-cyclodextrin and the site of binding with DNA are optimized by UV–Visible absorption, fluorescence, molecular modeling and Nuclear Magnetic Resonance spectroscopy techniques. The study of the effect of acid strength on the absorption and emission of Coumarin 7 in the presence and the absence of β-cyclodextrin shows that Coumarin 7 becomes less basic in the excited state and the encapsulation by the host molecule makes it less susceptible to get protonated. Coumarin 7 is encapsulated by β-cyclodextrin, forming a 1:1 inclusion complex. It binds to DNA with a binding constant of 3.45 × 10 5   M −1 . The role of β-cyclodextrin on the binding of Coumarin 7 with calf thymus DNA is explained. The possibility of β-cyclodextrin encapsulation to the exposed parts of Coumarin 7–calf thymus DNA complex is reported. These studies provide insight to increase the aqueous solubility and bioavailability of Coumarin 7 by the formation of an inclusion complex with β-cyclodextrin. Graphical Abstract