Binding Interaction of Glycated, Fructated and Native Human Hemoglobin with Bulk Propolis

Recently, the great interests in application of natural product have led to focus on the potential impact on bio macromolecules. Propolis is one of the natural products with various biological activities such as anti-diabetic effect. Under hyperglycemia, hemoglobin (Hb) frequently undergoes non-enzymatic glycation which affect its structure and function. In this study, the binding interaction between bulk propolis and three forms of Hb, native Hb, glycated Hb (GHb) and fructated Hb (FHb), in two temperatures of 25 and 37 °C have been examined and compared with our previous study (interaction of propolis nanoparticles with Hb, GHb and FHb). The binding studied with applying fluorescence and far UV circular dichroism spectroscopic techniques. Bulk Propolis possess the ability to quench the intrinsic fluorescence of the different types Hb like propolis nanoparticles. The mechanism of interaction bulk propolis with different types Hb was similar to the propolis nanoparticles, dynamic quenching in native Hb and static quenching in glycated and fructated Hb. According to the modified Stern–Volmer equation, the binding constant and number of binding sites were obtained. The result suggested that propolis nanoparticles have more quenching rate constant (kq) in compared to the bulk propolis in interaction different types Hb. In addition, the values of binding constant (Kb) revealed that nanopropolis has more binding affinity in compared to the bulk propolis. Data obtained from thermodynamic parameters implied more portion of electrostatic forces in GHb-propolis than native Hb-propolis and more hydrophobic portion in FHb-propolis. The CD spectra of Hb, GHb and FHb displayed no significant changes in secondary structure after incubated with propolis. These data are agreement with propolis nanoparticles. Results showed that propolis nanoparticles are a stronger quencher and bound to Hb, GHb and FHb with higher affinity than bulk propolis.