Spectroscopic analysis of interaction between galangin and human serum albumin

Under the imitated physiological condition, the interaction between galangin and human serum albumin ( HSA) was studied by fluorescence quenching, synchronous fluorescence, three-dimensional fluorescence and circular dichroism spectra.The results suggested that galangin had a strong ability to quench the HSA fluorescence in a static mode, during which hydrogen bond and Van Edward force played dominant roles. The binding constants ( K_a) and site numbers ( n) obtained at different temperatures were 1.26 × 10⁶L/mol, 1.17 ( 290.15 K) , 4.34 × 10⁵L/mol, 1.09 ( 296.15 K) , 1.23 × 10⁵L/mol, 1.00 ( 303.15 K) , 9.87 × 10⁴L/mol, 0.99 ( 310.15 K) , respectively. Spectra of synchronous fluorescence, three-dimensional fluorescence and circular dichroism revealed that galangin interacted with tryptophan residues in BSA more strongly than with tyrosine residues, and the vicinity of tryptophan residues was less hydrophobic.However, conformational changes of HAS were slighter.