In order to improve the bioavailability of lutein (LUT), a novel lutein-stevioside nanoparticle (LUT-STE) were prepared previously, but the information about LUT-STE on protecting of eye health was limited. This study investigated the effect of LUT-STE on antioxidant activity of H₂O₂-induced human retinal pigment epithelial (ARPE) cells. LUT and LUT-STE (final concentration of 5 μg/mL) significantly enhanced cell viability from (74.84 ± 5.10)% to (81.92 ± 10.01)% (LUT) and (89.33 ± 4.34)% (LUT-STE), and inhibited the cell apoptosis (P < 0.05). After pretreatment with LUT-STE in ARPE cells, the levels of superoxide dismutase (SOD), catalase (CAT) and glutathion peroxidase (GSH-Px) in ARPE cells were significantly increased (P < 0.05), the contents of reactive oxygen species (ROS) and malondialdehyde (MDA) were decreased. In addition, the vascular endothelial growth factor (VEGF) levels were inhibited by 13.61% and 17.39%, respectively, pretreatment with LUT and LUT-STE. Western blotting results showed that the pretreatment with LUT-STE inhibited the expression of caspase-9 and caspase-3 and up-regulated Bcl-2/Bax pathway to inhibit H₂O₂-induced apoptosis. In summary, the novel delivery LUT-STE had more pronounced inhibitory effect on H₂O₂-induced damage in human ARPE cells.

β-Carotene, a typical non-oxygenated carotenoid, is the most efficient source of retinol (VA). The low bio-availability of β-carotene lead to large accumulation in colon; however, the relationship between β-carotene and gut microflora remains unclear. This study intends to explore the interaction between β-carotene and gut microflora using an in vitro fermentation model. After 24 h fermentation, the degradation rate of β-carotene was (64.28 ± 6.23)%, which was 1.46 times that of the group without gut microflora. Meanwhile, the production of VA was nearly 2 times that of the group without gut microflora, indicating that the gut microflora can metabolize β-carotene into VA. β-Carotene also influences the production of short-chain fatty acids (SCFAs), the production of total SCFAs in 0.5 mg/mL β-carotene (BCM) group was (44.00 ± 1.16) mmol/L, which was 2.26 times that of the blank control (BLK) group. Among them, the production of acetic acid in BCM group was (19.06 ± 0.82) mmol/L, which was 2.64 time that of the BLK group. Furthermore, β-carotene significantly affected the structure and composition of gut microflora, increasing the abundance of Roseburia, Parasutterella and Lachnospiraceae, and decreasing the abundance of Dialister, Collinsella and Enterobacter (P < 0.05). This study provides a new way to understand how β-carotene works in human body with gut microflora.