Study on the interaction between human serum albumin and a novel bioactive acridine derivative using optical spectroscopy.

The interaction of a novel bioactive agent N-{[N-(2-dimethylamino) ethyl] acridine-4-carboxamide}-α-alanine [N-(ACR-4-CA)-α-ALA] with human serum albumin (HSA) was investigated by fluorescence spectroscopy, UV-vis absorption and circular dichroism spectrophotometric techniques under simulative physiological conditions. The fluorescence quenching of HSA by addition of N-(ACR-4-CA)-α-ALA is due to static quenching and hydrogen bonding. Moreover, hydrophobic interactions play a role in the binding of N-(ACR-4-CA)-α-ALA to HSA as well. The number of binding sites, n, and the binding constant values, K(A), were noted to be 0.88 and 3.4 × 10(4) L mol(-1) for N-(ACR-4-CA)-α-ALA at 293 K. The binding distances and the energy transfer efficiency between N-(ACR-4-CA)-α-ALA and protein were determined. The negative value of enthalpy change and positive value of entropy change in the present study indicated that both hydrogen bonding and hydrophobic forces played a major role in the binding of N-(ACR-4-CA)-α-ALA to HSA.