Detection of Simulated In Vitro Digestion Products of Fucoxanthin and Their Photodamage Alleviation Effect in Retinal Müller Cells Induced by Ultraviolet B Irradiation: A Proteomics Analysis.

Our previous study reported that the marine dietary bioactive compound fucoxanthin (FX) has the potential to reduce the level of oxidation in retinal Müller cells (RMCs) induced by ultraviolet B (UVB) irradiation. However, the gastrointestinal environment can inhibit the bioavailability and absorption of FX in the cell systems. In the current study, FX was initially digested in a simulated in vitro gastrointestinal fluid. Nine main digestive products were identified, and the photoprotective activities of FX simulated in vitro gastrointestinal digestion products (FX-ID) were assessed in the same RMC model. FX-ID significantly reduced intracellular ROS and alleviated apoptosis. Western blot assays showed that FX-ID inhibited phosphorylated proteins in the MAPK and NF-κB signaling pathways. Our proteomics analysis revealed that the differentially expressed proteins were linked to biological networks associated with antioxidation and metabolic processes. The data may provide insight into the photoprotective mechanisms of FX-ID and promote the development of various functional foods to prevent retinal disorders.

Digestion behavior of a polysaccharide from Cyclina sinensis: An explanation for the discrepancy in its immunostimulatory activities in vitro and in vivo.

Although numerous polysaccharides have demonstrated potential immunostimulatory activities in in vitro models, only a few of them successfully stimulate the immune system in vivo. In order to explore the possible reasons for the activity loss of polysaccharides in in vivo models, the immunostimulatory activities in vitro and in vivo and the digestion behavior of a polysaccharide from Cyclina sinensis (CSP) were investigated in the present study. CSP showed obvious immunostimulatory activity in a RAW 264.7 cell model. In in vitro experiment, CSP did not exhibit cytotoxicity at concentrations of ≤10 µg/ml, and significantly increased NO production at concentrations of 0.4-10 µg/ml, suggesting CSP processes immunostimulatory activity in vitro. Further investigation using simulated digestion model indicated that CSP could bind with the protein in the digestive fluids to form precipitate in both the stomach and small intestine, and it could be seriously degraded by amylase during the digestion in the small intestine. Furthermore, the in vivo immunostimulatory activity evaluation demonstrated CSP had no effect on immunosuppressed mice as indicated by the body weight, thymus and spleen indexes, and TNF-α, IL-1ß, IL-6, and IL-10 mRNA expression. Thus, the present study indicates that the degradation and precipitation of CSP in the digestive tract are the possible reasons for the activity loss of CSP after digestion. PRACTICAL APPLICATION: Cyclina sinensis is the common aquatic shellfish in China and plays an important role in the marine aquaculture industry. Cyclina sinensis polysaccharide (CSP) is the main active component of C. sinensis. The structure characterization and immunostimulatory activity of a purified fraction of CSP (CSP-1) and the effect of digestion on CSP and its immunostimulatory activity were studied. The result of this study promotes the understanding of the nutritional function effects and provides a scientific reference for the rational development and high-value utilization of C. sinensis.

Photoprotective Mechanism of Fucoxanthin in Ultraviolet B Irradiation-Induced Retinal Müller Cells Based on Lipidomics Analysis.

Long-term exposure to sunlight and/or blue light causes vision damage to people of all ages. Dietary pigments and polyphenols have been shown to have photoprotective potential for eyes; however, many unknowns regarding the protective mechanism remain. In this study, we used ultraviolet B (UVB) irradiation-induced retinal Müller cells (RMCs) to screen for dietary polyphenols and pigment compounds with effective photoprotective activity. Fucoxanthin (FX) was shown to have the best therapeutic effect, and the mechanism was evaluated via lipidomics analysis. Both intra- and extracellular ROS, mitochondrial depolarization, and DNA damage induced by UVB irradiation were inhibited by FX. Meanwhile, FX modulated the MAPK signaling pathway, which is correlated with apoptosis and inflammation. Our lipidomics data revealed that FX regulated lipid metabolism disorder and protected the membrane structure. These results confirm the effective photoprotective effects of FX, which may lead to new insights into FX-functionalized photoprotective foods.

Influence of Domestic Cooking on Quality, Nutrients and Bioactive Substances of Undaria pinnatifida.

Undaria pinnatifida (UP) is a brown algae commonly consumed as food in Asian countries. The purpose of this study was to compare the effects of different domestic cooking methods (i.e., air frying (AF), microwaving, and high temperature and pressure (HTP) cooking) on the nutritional and bioactive substances in UP, as well as on UP color and texture, in order to identify methods to retain beneficial components better. In this study, microwave treatment resulted in better retention of color, polysaccharide (4.17 ± 0.07 mg glucose equivalents (GE)/g dry weight (dw) ), total phenol content (TPC) (1.50 ± 0.0062 mg gallic acid equivalents (GAE)/g dw) as well as chlorophyll a (18.18 ± 0.41 mg/g fresh weight (fw) ) and fucoxanthin (281.78 ± 17.06 µg/g dw). HTP treatment increased the TPC of UP (1.69 ± 0.0075 mg GAE/g dw), and AF treatment resulted in a lower loss of total amino acids (2.14 ± 0.15%). Overall, microwave cooking appeared to be the best among the three in producing cooked UP with high quality. This study provided a useful guideline in selection of cooking for UP which could retain more health-beneficial substances and yield products with better eating qualities to improve human diet.