Stability of Differently Modified Lutein Nanostructured Lipid Carriers During Colonic Digestion and Their Interaction with Feces Microbiota

To prepare different types of lutein nanostructured lipid carriers (LNLs) using chitosan (CS), chitosan-epigallocatechin gallate covalent (C-CS-EGCG), and chitosan-epigallocatechin gallate ester non-covalent (Non-C-CS-EGCG) modifications combined with high-pressure microfluidization. A simulated colonic digestion model was established to investigate the stability and interaction with gut microbiota of these modified lutein nanostructured lipid carriers. Results showed that after 24 hours of simulated in vitro colonic fermentation, the lutein content in CS-LNLs significantly decreased (P<0.05) compared to other treatment groups. Except for lutein and CS-LNLs, the total sugar content in the fermentation supernatant significantly decreased (P<0.05) in other treatment groups, while the total polyphenol content in C-CS-EGCG-LNLs and Non-C-CS-EGCG-LNLs showed an opposite trend. After 24 hours of fermentation, the production of acetic acid and propionic acid significantly increased (P<0.05) in all treatment groups except the LUT group, with the acetic acid concentration reaching 17.18±0.60 mmol/L in the C-CS-EGCG-LNLs group. The lactic acid concentration reached 2.87±0.05 mmol/L, significantly higher (P<0.05) than the blank control group (BLK) by 7.55 times. The three different types of modified lutein nanostructured lipid carriers had a significant impact on the gut microbiota structure. The relative abundance of Bacteroides, Bifidobacterium, and Faecalibacterium significantly increased (P<0.05) in CS-LNLs, C-CS-EGCG-LNLs, and Non-C-CS-EGCG-LNLs, while C-CS-EGCG-LNLs enriched more Veillonella. Conclusion: Compared to other modification groups, C-CS-EGCG-LNLs had significant intestinal microbial structural differentiation in the colon digestive phase of nanoliposomes.