Thermodynamic characterization of dexamethasone sodium phosphate and its complex with dna as studied by conductometric and spectroscopic techniques

Abstract

Electrical conductivities were measured to calculate critical aggregation concentration (cac) of dexamethasone sodium phosphate (DSP) at various temperature from 298-313K with an increment of 5 K and in this way its thermodynamic parameters like Gibbs energy of aggregation (ΔGagg), enthalpy of aggregation (ΔHagg) and entropy of aggregation (ΔSagg) were estimated. The results demonstrate that DSP forms enthalpy driven aggregates through open association process. Furthermore, its interaction with DNA was studied by UV-Vis spectroscopy. The binding constant of DSP-DNA interaction was evaluated at 298 K and 310 K. Gibbs energy of drug-DNA complexation was determined by ΔG = -RT ln Kb, enthalpy of its interaction (ΔΗ) and entropy of adduct formation (ΔS) were obtained from Van't Hoff equation.