Binding of 6-methyl-3-phenyliminomethyl-4H-chromen-4-one with bovine serum albumin in free and β-cyclodextrin-complexed forms: Modulation of the binding by β-cyclodextrin

Abstract We report in this paper that β-cyclodextrin modulates the binding of a Schiff's base derivative, 6-methyl-3-phenyliminomethyl-4H-chromen-4-one, with the protein bovine serum albumin. The stoichiometry, the association constant, and the mode of association of the derivative with β-cyclodextrin are investigated by ultraviolet-visible absorption, steady-state and time-resolved fluorescence, and proton nuclear magnetic resonance and two dimensional correlation spectroscopic techniques. The structure of the host–guest complex is proposed. The binding of the chromen-4-one with bovine serum albumin and the influence of the added β-cyclodextrin on the binding are reported. β-cyclodextrin is found to decrease the Stern–Volmer quenching constant and the binding strength of the compound with the protein. The donor-to-acceptor distance is altered by the addition of β-cyclodextrin as studied by Forster resonance energy transfer. The binding sites of the chromen-4-one with bovine serum albumin are reported by molecular modeling.