| Abstract | We report on steady-state and ps-time-resolved emission studies of piroxicam (1) drug within human serum
albumin (HSA) protein in cyclodextrin and in neat solvents. The steady-state results indicate that 1 binds to
HSA protein and that two binding sites are involved. The fluorescence decays corresponding to site I in
subdomain IIA and to site II in subdomain IIIA have time constants of 60 ps and 360 ps, respectively.
The results suggest that the anion forms bind to site I, whereas the zwitterionic ones bind to site II. The
energy-transfer process from excited tryptophan to 1 can occur with moderate efficiency (50%). The rotational
time of 1 encapsulated by HSA indicates diffusion within the protein. These findings can be used for a
better understanding of piroxicam and HSA interactions. |