Abstract
To understand the expected mode of action, the physicochemical study on the solution properties of medicinal compounds and their interaction with deoxyribonucleic acid (DNA), under varying experimental conditions, is of prime importance. The present research work illustrates the physicochemical study and interaction of certain medicinal compounds such as; Levofloxacin, Ciprofloxacin, and Ibuprofen with DNA. Density, viscosity and surface tension measurements have been performed in order to determine, in a systematic manner, the physicochemical, volumetric and thermodynamic properties of these compounds; and most of these parameters have shown different behavior with varying concentration of solution, temperature of the medium and chemical nature/structure of the compound. In addition, these drugs showed a spontaneous surface-active and association behavior in aqueous solutions. The flow behavior, surface properties, volumetric behavior and solute–solvent interaction of these drugs were prominently influenced by experimental variables and addition of DNA to their solutions. UV–Visible spectroscopy was also used to examine the interaction of these drugs with DNA in aqueous media in detail. Calculated values of binding constants (Kb) for all complexes of drug-DNA are positive, indicating a fruitful binding process. It is seen that a smaller Kb value reflects weaker binding of the drug with DNA and vise versa. Due to the difference in the chemical structure of drugs the values of binding constant are different for various drug-DNA complexes and follow the order Kb(Levofloxacin-DNA) > Kb(Ciprofloxacin-DNA) > Kb(Ibuprofen-DNA). On the basis of spectral changes and Kb it can be said that the binding of all these drugs with DNA may be of physicochemical nature and the dominating binding force be of hydrogen bonding between oxygen of drugs and hydrogen of DNA units and the drug having more oxygen atoms showed stronger binding ability. The data further suggest a limited possibility of chemical type attachment of these drugs with DNA.
