| Tannic acid and resveratrol are natural polyphenols with antioxidant,anticancer and antiviral activities,which are very beneficial to human health.In this paper,firstly,tannic acid zein nanoparticles were prepared by antisolvent method,and the interaction between tannic acid and zein was explored by spectral analysis.Then,combined with the electrostatic deposition method,zein-anionic polysaccharide nanoparticles loaded with tannic acid were prepared to explore the effect of different charge characteristics of polysaccharides on the stability of nanoparticles,and to study the stability of nanoparticles under different environmental pressures（such as pH,ionic strength,temperature）,so as to determine the preparation conditions.Furthermore,the nanoparticles co-encapsulated tannic acid and resveratrol were prepared and their stability was reevaluated.The release behavior of tannic acid and resveratrol was explored by simulated in vitro digestion experiment,and its biological activity was explored by free radical scavenging,cytotoxic experiment and detection of intracellular antioxidant activity.The results were given as follows:1.The determination of hydrophobicity,UV spectra and fluorescence spectra revealed that the incorporation of tannic acid changed the hydrophobic environment around protein tyrosine and tryptophan to hydrophilic environment.Fourier transform infrared spectroscopy further confirmed that the self-assembly of tannic acid zein nanoparticles mainly involved hydrogen bonding,followed by hydrophobic action.2.The less electronegative polysaccharide precipitates the protein polysaccharide complex,while the more electronegative polysaccharide forms a stable nano-system with it.When the low ester pectin（0.11%,w/v）was used as stabilizer,the nanoparticles prepared had good stability in the range of pH 2.0-8.0.At pH 4.0,the particles were spherical,with good thermal stability（80℃,120 min）and high particle yield（95.1±1.3%）.The loading efficiency of tannic acid was 89.0±0.3%.3.The yield of co-encapsulated nanoparticles was high（89.87%-92.06%）,and the loading efficiency of tannic acid and resveratrol were51.54±1.87%and 77.20±3.21%,respectively.In the range of pH 2.0-8.0 or after heat treatment（80℃and 120 min）,the nanoparticles did not aggregate and remained stable in 40 m M NaCl solution.4.Free tannic acid was completely released within 60 min in the digestion phase of simulated gastrointestinal fluid,while the release behavior of tannic acid embedded in nanoparticles mainly occurred in the intestinal phase.For resveratrol,the release rate of resveratrol in co-encapsulated nanoparticles was higher than that of free resveratrol during the whole digestion period,and its bioavailability was 76.56%,which was also significantly higher than that of pure resveratrol powder（p<0.05）.5.The DPPH radical scavenging ability of co-encapsulated tannic acid and resveratrol nanoparticles(SC50=4.41μg/m L)was significantly higher than that of resveratrol nanoparticles(SC50=9.70μg/m L),but lower than that of tannic acid nanoparticles(SC50=3.02μg/m L).ABTS radical scavenging ability of co-encapsulated nanoparticles was slightly higher than that of single loaded tannic acid nanoparticles(SC50=71.52μg/m L),but significantly lower than that of single loaded resveratrol nanoparticles(SC50=54.14μg/m L).6.The IC50 value of resveratrol nanoparticles was 6 times higher than that of tannic acid nanoparticles（p<0.05）,indicating that tannic acid showed stronger cytotoxicity.However,the IC50 value of co-encapsulated nanoparticles on Hep G2 cells was significantly lower than that of their physical mixture（p<0.05）,and they were toxic to cells at the concentration of 6.3μg/m L.The results showed that tannic acid and resveratrol may have a synergistic effect on the inhibition of Hep G2 cells.7.Compared with the physical mixture group,the experimental group（co-encapsulated tannic acid and resveratrol nanoparticles）significantly reduced the content of MDA in Hep G2 cells（23.81%）,but slightly increased the activities of SOD and CAT.These results indicate that the combination of tannic acid and resveratrol in nanoparticles can improve the cell antioxidant activity. |
