Study On The Anti-Oxidative Stress,Anti-Inflammatory Effects,Protein Transport And Application Of Lutein Isomers

Lutein is an oxygen-containing carotenoid widely present in nature with strong antioxidant capacity and biological activity.All trans and different cis isomers as well as several conjugated double bonds are present in lutein molecules.Currently,most lutein research was concentrated on its all-trans configuration,while cis lutein research was primarily focused on configuration detection Previous studies had shown that cis lutein has better antioxidant activity than all trans lutein in terms of scavenging free radicals,but the differences in physiological activity（antioxidant stress,anti-inflammatory activity,etc.）in the human body were unknown.Lutein has also been found to be absorbed by the human body in the intestine through the assisted diffusion of lipid transport proteins,but whether there were differences in its transport efficiency for different configurations of lutein needed to be explored.Nanostructured lipid carriers products prepared from all trans lutein had been reported,and further research was needed to prepare products using high cis proportion lutein as raw material.In response to the above issues,this article used all trans lutein as raw material to efficiently prepare and purify cis lutein（9 cis and 13 cis）.Different Caco-2 cell models were established to compare the differences in anti-oxidative stress and anti-inflammatory effects,and the efficiency of lipid transport proteins in transport of different lutein isomers.A high cis ratio lutein nanostructured lipid carriers product with high bioavailability was prepared through single factor and orthogonal experiments.The main research findings were as follows:Study on the anti-oxidative stress effects of different lutein isomers.The iodine doped titanium dioxide（I-Ti O₂）catalyst can effectively catalyze the cis isomerization of all trans lutein,with isomerization efficiencies of 25.27%and 15.33%for 9 cis and 13 cis lutein,and chromatographic purity of 93.81%and 82.83%,respectively.By inducing oxidative stress in Caco-2 cells through H₂O₂ and adding different lutein isomers for treatment,low concentrations（2μM）cis lutein significantly inhibited the secretion of over 40%Interleukin-8（IL-8）,while cis lutein significantly inhibited the secretion of Interleukin-1β（IL-1β）（43%）and tumor necrosis factor-α（TNF-α）（57%）.In terms of its effect on endogenous antioxidant enzyme activity,cis lutein upregulated catalase（CAT）,glutathione reductase（GR）,and glutathione peroxidase（GPx）,with 9 cis lutein pointedly upregulating 20%CAT activity.In addition,lutein can substantially increase the content of endogenous antioxidant glutathione（GSH）and inhibit the secretion of malondialdehyde（MDA）.The anti-oxidative stress effects of cis lutein is significantly better than that of all trans lutein.Study on the anti-inflammatory effects of different lutein isomers.Using TNF-αinduce inflammation in Caco-2 cells.The results showed that treatment with different lutein isomers significantly inhibited the secretion of pro-inflammatory factors in Caco-2 cells,with 9 cis lutein（4μM）can inhibit the secretion of IL-8（25%）,and the inhibitory effect of 13 cis lutein（4μM）for IL-1βsecretion reached 23%.In terms of downregulation of pro-inflammatory genes,9 cis lutein and all trans lutein（4μM）can inhibit IL-8 genes by up to 50%,and 9 cis lutein can inhibit cyclooxygenase-2（COX-2）inflammatory genes by up to 26%.The anti-inflammatory effects of cis lutein was significantly better than that of all trans lutein.Study on the efficiency of transporting different lutein isomers through lipid transport proteins.Caco-2 cells was cultured and established a monolayer absorption model of intestinal epithelial cells by adding blockers to inhibit the activity of lipid transport proteins（Class B type1 scavenger receptors,SR-B1）.The results showed that the cell absorption efficiency of 9 cis lutein was inhibited by 20%followed by 13 cis 13%and all trans 10%.The results showed that the affinity between 9 cis lutein and SR-B1 were the highest.When the human body ingested different isomers of lutein at the same concentration,9 cis lutein could be preferentially absorbed through lipid transport proteins which partially explained the phenomenon that 9 cis lutein has high physiological activity in cells.Preparation of high cis proportion lutein nanostructured lipid carriers（cis-Lut-NLC）.By using high-pressure homogenization method,a product with a high cis proportion of lutein as raw material was prepared,which was superior to the product prepared with all trans lutein（Lut-NLC）in terms of lutein loading capacity,average particle size,and encapsulation efficiency.The optimal process conditions were obtained through single factor and orthogonal experiments as follows:lutein loading of 2.5%,total lipid concentration of 7.5%,MCT mass fraction of 60%,a surfactant concentration of 2 g/100 m L,homogenization pressure of 500 bar,and 3 times homogenization.In terms of bioavailability,by comparing the PF value variation curves of cis-Lut-NLC and Lut-NLC within 24 hours,the results showed that the bioaccessibility of cis-Lut-NLC was higher than that of Lut-NLC.