Binding of Ponceau 3R to Bovine Serum Albumin

Interaction of Two Commercial Azobenzene Food Dyes, Amaranth and New Coccine, with Human Serum Albumin: Biophysical Characterization

“…Since fluorescence quenching was identified without any blue-or red-shift to the maximum emission peak, there is an indication that these dyes interact close to the Trp residue without perturbing the microenvironment around it. 44,65 Differently from our data, in a study that used practically the same Albumin:New coccine proportion as ours, the fluorescence report for BSA:New coccine 35 indicated that this dye creates a more hydrophilic microenvironment around the Trp residues upon binding. There is not any previous fluorescence report for Amaranth.…”

“…From a structural point of view, the HSA has an asymmetric heart-like shape, with the highest percentage of structural motifs as α-helices. Its tertiary structure contains three homologous α-helical domains: I (residues 1–195), II (196–383), and III (384–585), and each domain is divided into two subdomains (A and B), presenting in each case one feasible binding site to interact with different types of small organic/inorganic compounds. − Since the binding between food dyes and HSA might significantly affect the absorption, distribution, metabolism, and toxicity of not only dyes but also endogenous metabolites or exogenous drugs, a vast literature reported the biophysical interaction between albumin and some azo-food dyes, highlighting the FDA-approved food dyes tartrazine (also known as acid yellow 23), − sunset yellow FCF, − citrus red 2, carmoisine, − allura red AC, − and FDA-unapproved dye ponceau 3R (Figure ). However, there is still not a deep biophysical report on the interaction between HSA and two of the widely used azo-food dyes in the industry: Amaranth and New coccine (E123 and E124, respectively, Figure ), e.g., for Amaranth, there is one report on its interaction with albumins and globulins of soybean and a preliminary interaction with HSA by an electrochemical technique, while for New coccine, there are preliminary reports on its interaction with bovine serum albumin (BSA). , …”