Interactions of aflatoxin B1 and related secondary metabolites with native cyclodextrins and their potential utilization

Abstract The attenuation or prevention of aflatoxins effect on agricultural products is still an unresolved problem due to the various influencing factors. Fluorescence fingerprint technique (such as excitation-emission matrix, EEM) has been developed for rapid detection of aflatoxins in liquid and solid samples. Unfortunately, the accuracy is seriously affected by background fluorescence compounds, such as kojic acid derivative (KAD). Therefore, development of more sensitive detection methods based on the enhancement of fluorescence signal is highly important. In this study, the EEM fluorescence technique was used to study the effects of α-, β-, and γ-cyclodextrins (CDs), and organic solvents on the fluorescence intensity of aflatoxin B 1 (AFB 1 ) and KAD, and molecular modeling study was also performed for the deeper understanding of these host-guest interactions. Results demonstrated that CDs and methanol could induce a higher fluorescence intensity of AFB 1 , while KAD presented a certain inhibitory effect on the enhancement of fluorescence signal of AFB 1 . Among the tested compounds β-CD formed the most stable conformation with AFB 1 (the logarithm of binding constant values are approximately 2.22–2.49) and the clathrate compounds caused the highest fluorescence enhancement of AFB 1 as well (the ratio of fluorescence intensity values ( I / I 0 ) for the presence and absence of CD at 430 nm are about 3.76–7.96). However, no obvious elevation for KAD fluorescence intensity caused by various CDs and organic solvents was observed at 493 nm. A significantly increase of fluorescence intensity was observed at the ratio of I 430 / I 493 by CDs. This suggested that CDs could be used to decrease the interference of KAD, and to improve the accuracy and sensitivity for detection of AFB 1 , especially for the low concentration level.