Fluorescence Spectroscopic Investigation of Competitive Interactions between Quercetin and Aflatoxin B(1) for Binding to Human Serum Albumin

Aflatoxin B(1) (AFB(1)) is a highly toxic mycotoxin found worldwide in cereals, food, and animal feeds. AFB(1) binds to human serum albumin (HSA) with high affinity. In previous experiments, it has been revealed that reducing the binding rate of AFB(1) with HSA could speed up the elimination rate of AFB(1). Therefore, we examined the ability of quercetin to compete with AFB(1) for binding HSA by fluorescence spectroscopy, synchronous spectroscopy, ultrafiltration studies, etc. It was shown that AFB(1) and quercetin bind to HSA in the same Sudlow site I (subdomain IIA), and the binding constant (K(a)) of the quercetin-HSA complex is significantly stronger than the complex of AFB(1)-HSA. Our data in this experiment showed that quercetin is able to remove the AFB(1) 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.