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Bioaccessibility, Cellular Uptake, and Transport of Astaxanthin Isomers and their Antioxidative Effects in Human Intestinal Epithelial Caco-2 Cells

Yang, Cheng, Zhang, Hua, Liu, Ronghua, Zhu, Honghui, Zhang, Lianfu, Tsao, Rong
Journal of agricultural and food chemistry 2017 v.65 no.47 pp. 10223-10232
antioxidant activity, astaxanthin, bioavailability, catalase, cis-trans isomerism, digestive system diseases, epithelium, geometric isomers, homeostasis, human cell lines, hydrogen peroxide, in vitro digestion, interleukin-8, models, oxidative stress, protective effect, secretion, superoxide dismutase
The bioaccessibility, bioavailability, and antioxidative activities of three astaxanthin geometric isomers were investigated using an in vitro digestion model and human intestinal Caco-2 cells. This study demonstrated that the trans–cis isomerization of all-E-astaxanthin and the cis–trans isomerization of Z-astaxanthins could happen both during in vitro gastrointestinal digestion and cellular uptake processes. 13Z-Astaxanthin showed higher bioaccessibility than 9Z- and all-E-astaxanthins during in vitro digestion, and 9Z-astaxanthin exhibited higher transport efficiency than all-E- and 13Z-astaxanthins. These might explain why 13Z- and 9Z-astaxanthins are found at higher concentrations in human plasma than all-E-astaxanthin in reported studies. All three astaxanthin isomers were effective in maintaining cellular redox homeostasis as seen in the antioxidant enzyme (CAT, SOD) activities ; 9Z- and 13Z- astaxanthins exhibited a higher protective effect than all-E-astaxanthin against oxidative stress as demonstrated by the lower cellular uptake of Z-astaxanthins and lower secretion and gene expression of the pro-inflammatory cytokine IL-8 in Caco-2 cells treated with H₂O₂. We conclude, for the first time, that Z-astaxanthin isomers may play a more important role in preventing oxidative stress induced intestinal diseases.