Fluorescence Spectroscopic Investigation of Competitive Interactions between Quercetin and Aflatoxin B1 for Binding to Human Serum Albumin

Abstract

Aflatoxin B1 (AFB1) is a highly toxic mycotoxin found worldwide in cereals, food, and animal feeds. AFB1 binds to human serum albumin (HSA) with high affinity. In previous experiments, it has been revealed that reducing the binding rate of AFB1 with HSA could speed up the elimination rate of AFB1. Therefore, we examined the ability of quercetin to compete with AFB1 for binding HSA by fluorescence spectroscopy, synchronous spectroscopy, ultrafiltration studies, etc. It was shown that AFB1 and quercetin bind to HSA in the same Sudlow site Ӏ (subdomain IIA), and the binding constant (Ka) of the quercetin-HSA complex is significantly stronger than the complex of AFB1-HSA. Our data in this experiment showed that quercetin is able to remove the AFB1 from HSA and reduce its bound fraction. This exploratory work may be of significance for studies in the future regarding decreasing its bound fraction and then increasing its elimination rate for detoxification. This exploratory study may initiate future epidemiological research designs to obtain further in vivo evidence of the long-term (potential protective) effects of competing substances on human patients.

Insight into the Molecular Interaction of Cloxyquin (5-chloro-8-hydroxyquinoline) with Bovine Serum Albumin: Biophysical Analysis and Computational Simulation

“…Hence, the findings suggested that cloxyquin interacts with BSA via static process by the ground-state complex formation. To further explore the mechanism of interaction, the fluorescence quenching of BSA as a result of cloxyquin exposure was analyzed by means of the modified Stern-Volmer equation as Equation (2) [26]. To further explore the mechanism of interaction, the fluorescence quenching of BSA as a result of cloxyquin exposure was analyzed by means of the modified Stern-Volmer equation as Equation (2) [26].…”

Indomethacin Increases Quercetin Affinity for Human Serum Albumin: A Combined Experimental and Computational Study and Its Broader Implications

“…In most cases, pharmacokinetic interactions involving displacement of xenobiotics from their carrier proteins is undesirable as it can lead to their higher active concentrations and potential adverse effects, or faster elimination and reduced efficiency (e.g., in cases of antibiotics which have time-dependent effectiveness [6]). However, in certain cases, displacement of xenobiotics is desirable, as it reduces their toxicity (e.g., displacement of ochratoxin [67] or aflatoxin B 1 [68] from HSA). In this regard, knowing to which one of the three possible types of ligand-ligand interactions our xenobiotic is subject to, can be of great importance in optimizing its desirable effects and preventing its undesirable effects, such as deliberately prolonging or shortening the xenobiotic half-life.…”

Antibacterial Activity of 2-Amino-1,4-naphthoquinone Derivatives Against Gram‑Positive and Gram-Negative Bacterial Strains and Their Interaction with Human Serum Albumin

“…53 On the other hand, when Dλ = 60 nm, the addition of NQA, NQC, and NQF to the albumin solution led to a slight red shift of the HSA signal (from 280 to 283; 288; and 288 nm for NQA, NQC, and NQF, respectively), indicating that they can perturb the microenvironment around the Trp-214 residue by increasing the polarity around this main albumin fluorophore. 54,55 Competitive binding studies and molecular docking analysis…”

“…Thus, it can be concluded that Sudlow's site I (subdomain IIA) is the primary binding pocket for NQA, NQC, and NQF. 20,54 Since experimental results indicated site I as the main protein's binding pocket for NQA, NQC, and NQF, molecular docking calculations were carried out to offer a molecular level explanation on the binding ability between HSA:naphthoquinones. Figure 7 depicts the best docking pose for each ligand inside subdomain IIA and Table 5 shows the main amino acid residues which can interact to each ligand, as well as its distance and type of intermolecular force.…”