Study On Zein As The Carrier Of Polyphenols

Zein is one of the protein components that make up corn.It is a unique and complex natural polymer material with high safety.Which is commonly used for the loading and transport of biologically active substances in foods and pharmaceuticals.Bioactive substances such as polyphenols have preferable antioxidation,anti-bacterial,anti-inflammatory,anti-viral properties,but their bioavailability is generally poor due to the low solubility and stability.Therefore,it is necessary to study the mechanism between zein and bioactive molecules in order to incorporate these bioactive substances to improve their stability and bioavailability.Based on this,this paper uses zein as the carrier to research the interaction mechanism between zein and small molecule polyphenols such as flavonoids and phenolic acids through fluorescence spectroscopy and molecular simulation methods.The zein-tannic acid mixture and conjugate were prepared,which were characterized and subjected to an antioxidant assay and an ?-glucosidase inhibition assay.The main contents and results are as follows:(1)The interaction between 21 kinds of flavonoids and zein was studied by fluorescence spectroscopy,and the binding constants and binding sites between them and zein were determined.The Topomer CoMFA model was constructed by 3D-QSAR for the research of the binding behavior and binding ability between flavonoinds and zein.The results showed that these flavonoids formed a complex with zein in a molar ratio of 1,flavonoids with glucosyl groups at ring A had the best binding capacity,which was driven by hydrophobic force.There was no significant change in the microenvironment around the tyrosine residue of zein during the binding process.(2)The interaction between 19 kinds of phenolic acids and zein was studied by fluorescence spectroscopy,and the binding constants and binding sites between them and zein were determined.The 15 descriptors related to the binding constants were screened by Dragon software.The correlation model was constructed by the Partial Least Squares(PLS)method,which was found to predictive,a well classfication of phenolic acid can be achieved.Hydroxycinnamic acid is mainly distributed on the right side of model,while hydroxybenzoic acid is mainly distributed on the left.The average connectivity index,3,7-order average topological charge index,aspect ratio,asphericity,spherical index and WHIM index played an important role in the process of binding between phenolic and zein.(3)The zein-tannic acid mixture and conjugate were prepared and characteried by UV-visible spectroscopy,fourier transform infrared spectroscopy,fluorescence spectroscopy,dynamic light scattering,circular dichroism,X-ray diffraction and differential scanning calorimetery.The results indicated that zein-tannic acid conjugate has a smaller particle size and a larger zeta potential(absolute value)than the mixture.So that the former has a good dispersibility in water.Antioxidant experiments and ?-glucosidase inhibition experiments suggested that zein-tannic acid conjugate possess well antioxidant capacity and ?-glucosidase inhibition ability due to the added of tannic acid.