Abstract
Herein, we have reported the study of interaction of model protein, bovine serum albumin (BSA), and a sipholane triterpenoid, named Sipholenone A. This triterpenoid in known to possess anticancer properties and was isolated from the Red Sea sponge Siphonochalina siphonellais.1H and 13C NMR were used to characterize the triterpenoid. Binding studies were carried out by using UV–visible and fluorescence spectroscopies and the conformational transition was seen by means of circular dichroism and FTIR spectroscopies. The hypochromic shift in UV spectrum of BSA in presence of Sipholenone A is an indication of the complex formation. The results also indicated that the fluorescence quenching of BSA at 340 nm by Sipholenone A caused due to the formation of Sipholenone A-BSA complex. The number of binding sites for Sipholenone A binding on BSA was found to be roughly equal to 1. Stern-Volmer analysis at various temperatures showed the involvement of the static quenching in the binding process. Sipholenone A binds to the site I of subdomain IIA and also causes changes in the secondary and tertiary structure of BSA and a consequent partial unfolding.
•Sipholane triterpenoid, sipholenone A, was synthesized from the Red Sea sponge and its interaction with BSA was studied.•The triterpenoid binds spontaneously at site I of subdomain IIA.•Partial unfolding of protein was also observed in the binding process.