Studies on the interactions of 3,6‐diaminoacridine derivatives with human serum albumin by fluorescence spectroscopy

This study reports the preparation and investigation of the modes of binding of the two symmetric 3,6‐diaminoacridine derivatives obtained from proflavine, which are 3,6‐diphenoxycarbonyl aminoacridine and 3,6‐diethoxycarbonyl aminoacridine to human serum albumin (HSA). The interaction of HSA with the derivatives was investigated using fluorescence quenching and ultraviolet‐visible absorption spectra at pH 7.2 and different temperatures. The results suggest that the derivatives used can interact strongly with HSA and are the formation of HSA‐derivative complexes and hydrophobic interactions as the predominant intermolecular forces in stabilizing for each complex. The Stern‐Volmer quenching constants, binding constants, binding sites and corresponding thermodynamic parameters ΔH, ΔS and ΔG were calculated at different temperatures. The binding distance (r) ~ 3 nm between the donor (HSA) and acceptors (3,6‐diethoxycarbonyl aminoacridine, 3,6‐diphenoxycarbonyl aminoacridine and proflavine) was obtained according to Förster's non‐radiative energy transfer theory. Moreover, the limit of detection and limit of quantification of derivatives were calculated in the presence of albumin. Copyright © 2014 John Wiley & Sons, Ltd.