The Interaction Of Curcumin With Biological Macromolecules In Food

How to use the interaction of polyphenols and biological macromolecules in food to invent new functional food for human health has attracted research interests widely in the current food research areas.Curcumin is a type of classical active small molecule with high biological activity,low water solubility and low bioavailability,whichis favored by medicine and health science because of its many excellent biological activities.In food,the research of curcuminis mainly limited in its function from monomer or thepreparation process of curcumin complex.However,there is little systematic research on the mechanism of the interaction between curcumin and bio-macromolecules in food,which is importantfor understanding the mechanism of curcumin on human health and the applicationfor new food ingredients with curcumin.In this paper,the interaction between curcumin and major macromolecules in food,such as lipids,polysaccharides and proteins,was systematically studied byclassical physical and chemical experimental techniques in combination with Molecular simulation.The further applicationof curcumin/macromoleculescomplex in the food fieldwas also discussed.The results are as follows:(1)The thermal stability test suggested that the structure ofliposomewas destroyed at about 50 °C wherehas a number of phase transitionsuch as a pre-phase transition andmajor phase transition.The structure of liposome was more prone to change when the curcuminwas inserted into the liposomes.Chitosan can effectively improve the storage stability and temperature stability by electrostatic interaction.Chitosan also can reduce the release rate of curcuminfrom liposome.The diffusion mechanism belongs tonon-Fickian(anomalous)calculated by release models.(2)The simulation model of lecithin,cholesterol,curcumin and chitosan was built by computer.Their interactionwas described by using the interaction parameters.The formationprocess of liposome and phospholipid bilayer were studied by DPD method.And the formation force processincluded three stages: uniform distribution,formatting small-scale polymers andformatting large-scale polymers.The dynamic model of phospholipid bilayer was built at first time.The relative position of curcumin in the phospholipid layer was located within the bimolecular layer and closer to the hydrophobic end of the lecithin.(3)The interaction between curcumin and chitosan was studied by preparing the curcumin-chitosan high polymer complex.Molecular dynamics simulation showed that the interaction between curcumin and chitosan was hydrogen bonds,which was further proved by FT-IR.The scan electron microscopy and thermogravimetric analysis showed that the curcumin has a good compatibility with chitosan;the crystallinity of the composite film was lower than that of pure chitosan membrane.Curcumin could significantly improve the rigidity,strength andhydrophilicity of pure chitosan film.In addition,the composite membranes showed a better antimicrobial activity compared to pure chitosan membranes,which could act as a promising antibacterial packaging for food and agricultural products.(4)In order to understand the binding ability of curcumin with protein and the characteristics of their composite system,the solubility,antioxidant capacity and light stability were studied.Curcumin and ovalbumin can form complexes by the interaction between each other.The X-ray diffraction and DSC results show that the crystal structure of curcumindisappeared,and the protein was more easy to pyrolyze.The complexationcould improve the solubility of curcumin about 370 times,showing a better antioxidant activity and light stability,which has a potentialapplication inthe functional food.(5)The binding process of curcumin and ovalbumin was studied by fluorescence titration experiment,molecular docking and circular dichroism.Curcumin binding behavior led to the protein fluorescence quenching,whichbelonged to static quenching.In addition,the fluorescence resonance energy transfer occurred between curcumin and ovalbumin.The binding process included two stages,at first,the curcumin was inserted into the protein hydrophobic pocket by hydrophobic interaction;secondly,the interaction can be enhanced by hydrogen bonds.The process can be described by the "Hands-gloves" model.The binding behaves led to the secondary structure changes of the protein,making its structure more unstable.