Resveratrol is a polyphenol belonging to the class stilbenes. The active and stable form of resveratrol is trans-resveratrol. This polyphenol is bestowed with numerous biological properties. Aflatoxin B1 is a hepato-carcinogen and mutagen that is produced by Aspergillus species. In this study, the interaction of trans-resveratrol with HSA followed by competitive dislodging of AFB1 from HSA by trans-resveratrol has been investigated using spectroscopic studies. The UV-absorption studies revealed ground state complex formation between HSA and trans-resveratrol. Trans-resveratrol binds strongly to HSA with the binding constant of ~ 107 M−1 to a single binding site (n = 1.58), at 298.15 K. The Stern–Volmer quenching constant was calculated as 7.83 × 104 M−1 at 298.15 K, suggesting strong fluorescence quenching ability of trans-resveratrol. Site markers displacement assay projected subdomain IIA as the binding site of trans-resveratrol to HSA. The molecular docking approach envisages the amino acid residues involved in the formation of the binding pocket. As confirmed from the site marker displacement assays, both trans-resveratrol and AFB1 binds to HSA in the same binding site, subdomain IIA. The study explores the ability of trans-resveratrol to displace AFB1 from the HSA-AFB1 complex, thereby affecting the toxicokinetic behavior of AFB1 associated with AFB1 exposure.
Aflatoxin B 1 (AFB 1 ) is a mutagen that has been categorized as a group 1 human carcinogen by the International Agency for Research on Cancer. It is produced as a secondary metabolite by soil fungi Aspergillus flavus and Aspergillus parasiticus. Here, in this study, the effect of AFB 1 on the structure and conformation of bovine serum albumin (BSA) using multispectroscopic tools like fluorescence spectroscopy, ultraviolet−visible absorption spectroscopy, and circular dichroism spectropolarimetry has been ascertained. Ultraviolet absorption spectroscopy revealed hyperchromicity in the absorption spectra of BSA in the presence of AFB 1 . The binding constant was calculated in the range of 10 4 M −1 , by fluorescence spectroscopy suggesting moderate binding of the toxin to BSA. The study also confirms the static nature of fluorescence quenching. The stoichiometry of binding sites was found to be unity. The competing capability of warfarin for AFB 1 was higher than ibuprofen as calculated from site marker displacement assay. Forster resonance energy transfer confirmed the high efficiency of energy transfer from BSA to AFB 1 . Circular dichroism spectropolarimetry showed a decrease in the α-helix in BSA in the presence of AFB 1 . The melting temperature of BSA underwent an increment in the presence of a mycotoxin from 62.5 to 70.3 °C. Molecular docking confirmed the binding of AFB 1 to subdomain IIA in BSA.
■ HIGHLIGHTS• In this study, binding dynamics of AFB 1 with BSA were explored by UV absorption spectroscopy, fluorescence spectroscopy, and molecular docking.• Molecular docking analysis substantiated that Arg-217, Tyr-149, Arg-256, and Ala-260 residues stabilize the interacting complex via hydrogen bonding.
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