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This study aimed to investigate the regulation of fucoxanthin (FX) biosynthesis under various nitrogen conditions to optimize FX productivity in Phaeodactylum tricornutum. Apart from light, nitrogen availability significantly affects the FX production of microalgae; however, the underlying mechanism remains unclear. In batch culture, P. tricornutum was cultivated with normal (NN, 0.882 mM sodium nitrate), limited (LN, 0.22 mM), and high (HN, 8.82 mM) initial nitrogen concentrations in f/2 medium. Microalgal growth and photosynthetic pigment production were examined, and day 5 samples were subjected to fucoxanthin–chlorophyll a/c-binding protein (FCP) proteomic and transcriptomic analyses. The result demonstrated that HN promoted FX productivity by extending the exponential growth phase for higher biomass and FX accumulation stage (P1), showing a continuous increase in FX accumulation on day 6. Augmented FX biosynthesis via the upregulation of carotenogenesis could be primarily attributed to enhanced FCP formation in the thylakoid membrane. Key proteins, such as LHC3/4, LHCF8, LHCF5, and LHCF10, and key genes, such as PtPSY, PtPDS, and PtVDE, were upregulated under nitrogen repletion. Finally, the combination of low light and HN prolonged the P1 stage to day 10, resulting in maximal FX productivity to 9.82 ± 0.56 mg/L/day, demonstrating an effective strategy for enhancing FX production in microalgae cultivation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Heating promoted the degradation of total, all-trans and 9′-cis fucoxanthin. [•] Heating promoted the formation of 13-cis and 13′-cis fucoxanthin. [•] First-order degradation or formation kinetics in the absence of air and light. [•] Aerial exposure promoted the oxidative degradation of fucoxanthin isomers. [•] Illumination promoted the formation of 9′-cis fucoxanthin. [ABSTRACT FROM AUTHOR]

Abstract: Fucoxanthin-loaded microspheres, composed of a cetyl palmitate (CP)–canola oil (CO) mixed solid lipid core and a fish gelatin–gum arabic complex coacervate shell cross-linked by tannic acid, were developed and characterized for efficient oral delivery of fucoxanthin. Two types of solid lipid-core microspheres (CP:CO=30:70 and 50:50) in both wet and freeze-dried forms were investigated in their morphology, size, moisture content, and fucoxanthin encapsulation efficiency, in comparison with oil–core microspheres (CP:CO=0:100). The melting and solidification of the cores were also analyzed by DSC. Compared to the oil–core microspheres, the solid lipid-core microspheres, especially of CP:CO=50:50, exhibited greatly enhanced sustained fucoxanthin release performance under a simulated gastrointestinal condition and much stronger fucoxanthin-stabilizing capability when stored in the dark atmosphere of 0% or 51% relative humidity at 40°C, although the encapsulation efficiency was lowered from 85.34% to 74.81% with the increase of the CP fraction from 0% to 50%. [Copyright &y& Elsevier]

Abstract: Optimization of extraction conditions for fucoxanthin from brown algae Eisenia bicyclis was investigated through a pressurized liquid extraction (PLE) method and statistical experimental design. The process was optimized by Plackett–Burman design at first step to screen the most important variables in the extraction of fucoxanthin, and subsequently central composite design was applied to attain the optimum conditions of the selected factors for fucoxanthin extraction. Two factors, temperature and ethanol concentration, significantly influenced the extraction efficiency of fucoxanthin at 95% level (P <0.05). The maximum predicted value of fucoxanthin extraction was 0.42mg/g at 110°C and 90% ethanol. The validation of the model was verified by triplicate experiments under the optimal conditions. The results demonstrated that the statistical strategy was successfully applied for optimization of PLE method for fucoxanthin extraction and that PLE can be a powerful method to extract fucoxanthin from E. bicyclis. [ABSTRACT FROM AUTHOR]

Fucoxanthin (FX), a marine carotenoid found in macroalgae and microalgae, exhibits several beneficial effects to health. The anti-obesity activity of FX is well documented, but FX has not been mass-produced or applied extensively or commercially because of limited availability of raw materials and complex extraction techniques. In this study, we investigated the anti-obesity effect of standardized FX powder (Phaeodactylum extract (PE)) developed from microalga Phaeodactylum tricornutum as a commercial functional food. The effects of PE on adipogenesis inhibition in 3T3-L1 adipocytes and anti-obesity in high-fat diet (HFD)-fed C57BL/6J mice were evaluated. PE and FX dose-dependently decreased intracellular lipid contents in adipocytes without cytotoxicity. In HFD-fed obese mice, PE supplementation for six weeks decreased body weight, organ weight, and adipocyte size. In the serum parameter analysis, the PE-treated groups showed attenuation of lipid metabolism dysfunction and liver damage induced by HFD. In the liver, uncoupling protein-1 (UCP1) upregulation and peroxisome proliferator activated receptor γ (PPARγ) downregulation were detected in the PE-treated groups. Additionally, micro computed tomography revealed lower fat accumulation in PE-treated groups compared to that in the HFD group. These results indicate that PE exerts anti-obesity effects by inhibiting adipocytic lipogenesis, inducing fat mass reduction and decreasing intracellular lipid content, adipocyte size, and adipose weight. [ABSTRACT FROM AUTHOR]

Highlights • Fucoxanthin degradation was much greater in o/w emulsion than in oil. • The 9′- cis fucoxanthin was more stable than the other isomers except at pH 1.2. • Fucoxanthin stability was the most significantly influenced by pH. • Fucoxanthin stability was more influenced by temperature than by light. • Total and all- trans fucoxanthin followed first-order degradation kinetics. Abstract The effects of temperature, light, and pH on the stability of fucoxanthin in an oil-in-water emulsion were investigated with analyzing the kinetics and thermodynamics of fucoxanthin degradation. In the absence of light and air at pH 4.6, increasing the temperature from 25 to 60 °C significantly promoted fucoxanthin degradation. Total and all- trans fucoxanthin demonstrated an energetically unfavorable, non-spontaneous degradation with an Arrhenius temperature dependence. Increasing the light intensity up to 2000 lx at 25 °C and pH 4.6 caused a sharp degradation of total, all- trans , 13- cis , and 13′- cis fucoxanthin, but promoted the formation of the 9′- cis isomer. In the absence of light and air at 25 °C, decreasing the pH to 1.2 caused significant fucoxanthin degradation, whereas increasing the pH to 7.4 retarded the degradation. The property with the greatest influence on fucoxanthin stability was pH, followed by temperature and then light. Total and all- trans fucoxanthin followed first-order degradation kinetics. [ABSTRACT FROM AUTHOR]

Our previous study reported the improved stability of fucoxanthin (FX) fortified in whole milk (WM) and skimmed milk (SM). In this study, in vivo and in vitro FX bioavailability were investigated using FX-fortified milk (FX-SM and FX-WM) and microalga Phaeodactylum tricornutum biomass (Pt-powder). Organ tissue accumulation of FX and its metabolites (FXOH: fucoxanthinol, AXA: amarouciaxanthin A) after repeated oral administration was in the following order: FX-SM > FX-WM > Pt-powder. In vivo pharmacokinetic study with a single oral administration also demonstrated that the absorption of FXOH and AXA was the highest for FX-SM. To reinforce the in vivo results, in vitro -simulated digestion and Caco-2 cell uptake assays were performed, which revealed that FX-SM showed the highest FX bioaccessibility (release from food matrices) and cellular uptake efficiency of FX and FXOH. In conclusion, skimmed milk was validated as an excellent food matrix for FX application in terms of stability and bioavailability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two nanoparticles showed an encapsulation efficiency of fucoxanthin (FX) over 78%. • FX in nanoparticles showed a controlled release in the simulated gastrointestinal tract. • A membrane permeability of FX in nanoparticles was improved by 1.8-folds in Caco-2/TC7 cells. • FX metabolites from nanoparticles were absorbed more (31.8 %–332.1 %) into the mouse plasma. The marine carotenoid fucoxanthin (FX) has various health benefits but suffers from poor bioavailability. We hypothesize that the bioavailability of FX in microalga Phaeodactylum tricornutum extract (PE) could be improved through nanoencapsulation. Here, we developed two types of nanoparticles: one consisting of alginate and casein (A-C-PE, 246 nm diameter, 79.6% encapsulation efficiency) and the other A-C-PE coated with chitosan (CS-A-C-PE, 258 nm, 78.1%). Both types of nanoparticles incorporating PE showed controlled FX release during simulated gastrointestinal digestion, as well as 1.8-fold improvement of membrane permeability in Caco-2/TC7 cells compared to non-encapsulated PE. Pharmacokinetic behavior of two FX metabolites (fucoxanthinol and amarouciaxanthin A) in mouse plasma was monitored after oral administration. The results showed that 31.8–332.1% more FX metabolites from the nanoparticles were absorbed into plasma than those from PE. In conclusion, encapsulation of PE in both types of nanoparticles significantly promoted the bioavailability of FX. [ABSTRACT FROM AUTHOR]