Abstract
Some new and known coumarincarboxylic acids were synthesized for use as fluorescence probes. The fluorescence properties of these compounds were examined in various solvents and albumin solutions. The fluorescence of 7-anilinocoumarin-4-acetic acid (I) was significantly enhanced in nonpolar solvents and in the presence of human serum albumin (HSA). The binding parameters of I were estimated from the fluorescence enhancement and spectral change of I bound to HSA. The Scatchard plots and the continuous variation plots indicated that only the primary site was capable of enhancing the fluorescence and causing the spectral changes of I. Digitoxin displaced I from its primary site on HSA, but site 1 and site 2 drugs on the basis of Sudlow's classification did not significantly displace the probe. The present data indicate that I may be useful as a third site marker.
