Study on the interaction between novel spiro pyrrolidine and bovine serum albumin by spectroscopic techniques

Spiro pyrrolidines, which were proved with diverse and potent biological activities and they were discovered widespread in nature. In this paper, using fluorescence and ultraviolet spectroscopy, we investigated the interactions between novel spiro pyrrolidine (NSP) and bovine serum albumin (BSA) under the imitated physiological condition. The results show that the NSP binds to BSA molecules. Static quenching and non-radiation energy transfer are the main reasons for fluorescence quenching. We calculated the binding constant (Ka) and binding sites (n) at different temperatures and obtained the binding distance between the tryptophan residue in BSA and the NSP based on the Förster theory of non-radiation energy transfer. In addition, using synchronous fluorescence spectra, we demonstrated conformation changes of BSA caused by NSP. The comparison of binding potency of NSP and BSA suggests that the substituent on the benzene ring influences the binding ability of NSP and BSA.

Graphical abstractThe interaction between novel spiro pyrrolidine (NSP) and bovine serum albumin (BSA) was studied by fluorescence and UV–vis spectroscopy. The quenching mechanism, binding constants, and binding distance were obtained. Conformation change of BSA was observed from synchronous fluorescence spectra. The comparison of binding potency of NSP and BSA suggested that the substituents on the benzene ring influence the binding affinity of NSP and BSA.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We explored the interaction between BSA and NSP by spectroscopic methods. ► The fluorescence quenching mechanism is static quenching. ► The binding constants and binding sites were calculated. ► The conformation of BSA was changed affected by NSP. ► The substituent on the benzene ring influences the binding affinity of NSP and BSA.