The　interaction　between　pyrrolizine　derivatives　(PD)　and　bovine　serum　albumin　(BSA)　under　imitated　physiological　conditions　was　analyzed　by　fluorescence　and　ultraviolet　spectra.　The　experiments　were　conducted　at　three　different　temperatures　(302,　306　and　310　K)　and　the　results　showed　that　PD　caused　the　fluorescence　quenching　of　BSA　through　a　combined　quenching　procedure.　The　binding　constant　(K-a),　binding-site　number　(n)　between　PD　and　BSA　at　different　temperatures　were　obtained.　According　to　Forster　non-radiation　energy　transfer　theory,　the　binding　distance　(r)　between　BSA　and　PD　was　calculated.　The　corresponding　thermodynamic　parameters　(Delta　G,　Delta　H,　and　Delta　S)　were　also　obtained.　The　comparison　of　binding　potency　of　PD　and　BSA　suggested　that　the　substituent　on　the　benzene　ring　could　enhance　the　binding　affinity　of　PD　and　BSA.　Finally,　we　investigated　the　possible　sub-domain　on　BSA　where　bind　PD　by　displacement　experiments.　(C)　2012　Elsevier　B.V.　All　rights　reserved.