The　interaction　of　a　novel　bioactive　agent　N-{[N-(2-dimethylamino)　ethyl]　acridine-4-carboxamide}-alpha-alanine　[N-(ACR-4-CA)-alpha-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)-alpha-ALA　is　due　to　static　quenching　and　hydrogen　bonding.　Moreover,　hydrophobic　interactions　play　a　role　in　the　binding　of　N-(ACR-4-CA)-alpha-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　x　10(4)　L　mol(-1)　for　N-(ACR-4-CA)-alpha-ALA　at　293　K.　The　binding　distances　and　the　energy　transfer　efficiency　between　N-(ACR-4-CA)-alpha-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)-alpha-ALA　to　HSA.　Copyright　(C)　2010　John　Wiley　&　Sons,　Ltd.