Studies on the Interaction of Rose Bengal with the Human Serum Albumin Protein under Spectroscopic and Docking Simulations Aspects in the Characterization of Binding Sites

Abstract

Rose Bengal (RB) is a xanthene dye used as a sensitizer to convert triplet (3O2) to singlet oxygen (1O2). This photophysical property makes it one of the most used dyes in photodynamic therapy. Thus, understanding its interaction with biomacromolecules can provide helpful information about its mode of action and application. The protein chosen for this study was human serum albumin (HSA), which has nine binding sites for fatty acids (FA), and at least three sites for interactions of drugs (DS). The complexation of HSA with RB caused a maximum bathochromic shift in its absorption. From this displacement and the application of the Benesi–Hildebrand model, the ligand–protein association constant (3.90 ± 0.08 × 105 M−1) was obtained. Applying the Job’s Plot method resulted in a 6:1 (ligand-protein) stoichiometry. The determination of preferred binding sites was performed by measuring the association constant in the presence of drugs for which their binding sites in HSA are already well established, such as warfarin (DS1), ibuprofen (DS2 and FA6), digitoxin (DS3), diazepam (DS2), and diflunisal (DS2 and FA6). From these studies, it was found that RB is able to bind at DS1, DS3, and FA6 sites but not at DS2. Subsequently, molecular docking studies using the 2BX8 and 2BXE crystallographic structures were performed and corroborated the experimental results. The lowest energy poses were −52.13, −58.79, and −67.55 kcal mol−1 at DS1, DS3, and FA6, respectively. Conversely, DS2 was the lower affinity binding site. In conclusion, HSA has a high affinity for RB, being able to bind up to six dye molecules.

Copper(ii) complexes of a furan-containing aroylhydrazonic ligand: syntheses, structural studies, solution chemistry and interaction with HSA

“…Each domain is grouped into subdomains A and B, with common structural motifs. 78,79 Our studies were initially focused on the three drug interaction sites (DS), located in the regions IIA (DS1), IIIA (DS2) and IB (DS3), and then extended to the FA6 region. The best interactions were obtained around DS2 (using a study radius of 10 Å) and FA6 (9 Å) sites.…”

Induced Chirality in Sulfasalazine by Complexation With Albumins: Theoretical and Experimental Study

“…The transport occurs due to the fact that these proteins have cavities (interaction sites) composed of amino acid residues that interact favorably with smaller molecules, endogenous or exogenous. Drugs have certain preferred sites comprising drug site 1 (DS1), drug site 2 (DS2), and drug site 3 (DS3) [1,[5][6][7]. The determination of the interaction site can be done through the study of changes in the association constant (K a ) of the complex of interest as a function of probes whose interaction sites are already well established in the literature [5,7].…”

“…Drugs have certain preferred sites comprising drug site 1 (DS1), drug site 2 (DS2), and drug site 3 (DS3) [1,[5][6][7]. The determination of the interaction site can be done through the study of changes in the association constant (K a ) of the complex of interest as a function of probes whose interaction sites are already well established in the literature [5,7]. The drug sulfasalazine (SSZ), used in the treatment of inflammatory bowel diseases, is indicated in the literature as having affinity for the region comprising DS1 of HSA and BSA [8][9][10][11][12].…”