Probing the interactions of hemoglobin with antioxidant flavonoids via fluorescence spectroscopy and molecular modeling studies

►Distinctive 'two color' fluorescence signatures and fairly high fluorescence anisotropy of fisetin (3,7,3′,4′-OH-flavone) and 3-hydroxyflavone reveal their binding with HbA. ►Specific interactions with HbA are confirmed from the static nature of the flavonoid-induced quenching of protein tryptophan fluorescence. ►Molecular docking and electrostatic surface potential calculations reveal contrasting binding modes of fisetin and 3-hydroxyflavone with HbA.