Fucoxanthin (all-trans-Fucoxanthin)

Effects of temperature, light, and pH on the stability of fucoxanthin in an oil-in-water emulsion

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.

Characterization of dietary fucoxanthin from Himanthalia elongata brown seaweed

This study explored Himanthalia elongata brown seaweed as a potential source of dietary fucoxanthin which is a promising medicinal and nutritional ingredient. The seaweed was extracted with low polarity solvents (n-hexane, diethyl ether, and chloroform) and the crude extract was purified with preparative thin layer chromatography (P-TLC). Identification, quantification and structure elucidation of purified compounds was performed by LC-DAD-ESI-MS and NMR (¹H and ¹³C). P-TLC led purification yielded 18.6mg/g fucoxanthin with 97% of purity based on the calibration curve, in single-step purification. LC-ESI-MS (parent ion at m/z 641 [M+H-H2O]⁺) and NMR spectra confirmed that the purified band contained all-trans-fucoxanthin as the major compound. Purified fucoxanthin exhibited statistically similar (p>0.05) DPPH scavenging capacity (EC₅₀: 12.9μg/mL) while the FRAP value (15.2μg trolox equivalent) was recorded lower (p<0.05) than the commercial fucoxanthin. The promising results of fucoxanthin purity, recovery and activity suggested that H. elongata seaweed has potential to be exploited as an alternate source for commercial fucoxanthin production.

Fucoxanthin from Undaria pinnatifida: photostability and coextractive effects

Fucoxanthin is one of the most abundant carotenoids and possesses a number of beneficial medicinal qualities which include its anti-oxidant, anti-obesity and anti-cancer properties. In this study, the photostability of fucoxanthin in extracts with different chemical profiles was studied. The extracts were obtained from Undaria pinnatifida, a seaweed rich in this carotenoid, using conventional liquid solvent extraction procedures and the QuEChERS method. All the extracts contained all-trans-fucoxanthin as the major compound. Conventional procedures produced a fucoxanthin purity of lower than 50%, whereas after liquid-liquid partition, PSA cleanup, and PSA and GCB cleanup (QuEChERS method) fucoxanthin purity increased to 70%, 86%, and 94%, respectively. Although in the acetone extract the initial content of fucoxanthin was the highest, results demonstrate that coextractives play an important role in enhancing the rate of photodegradation. After light exposure, the conventional extracts lost around 90% of the initial fucoxanthin content. On the other hand, the extracts obtained by the QuEChERS method showed significantly higher light stability than the conventional extracts. These results suggest that the QuEChERS method could be used and further improved to obtain more purified and stable extracts for fucoxanthin from U. pinnatifida.

Effect of Isomerization on Excited-State Dynamics of Carotenoid Fucoxanthin

Ultrafast transient absorption spectroscopy and single-wavelength anisotropy measurements were used to study the effect of isomerization on the excited-state properties of fucoxanthin in polar and nonpolar solvents. The excitation wavelengths were 477 nm for all-trans-fucoxanthin, and 333 and 477 nm for cis-fucoxanthin. All transient absorption spectra of the fucoxanthin isomers in polar solvents show intramolecular charge transfer (ICT) state features, typical for carbonyl carotenoids. Global analysis of the data requires an additional fitting component, originated from the presence of blue and red forms of fucoxanthin in a polar protic solvent. Here we demonstrate that the ICT state decays faster than the S₁ state, due to the significant contribution of the red form to the ICT state dynamics. The isomerization does not affect the S₁ lifetime, but induces a larger difference between the S₁- and ICT-state lifetimes in cis-fucoxanthin, which is likely caused by alterations of ICT coupling to either the S₁ or S₀ states; the S*-state signal is more pronounced for cis-isomers in a nonpolar solvent.

Effects of heating, aerial exposure and illumination on stability of fucoxanthin in canola oil

The effects of heating, aerial exposure and illumination on the stability of fucoxanthin was investigated in canola oil. In the absence of air and light, the heating caused the degradation of total and all-trans fucoxanthin at all tested temperatures between 25 and 100 °C. The increase of heating temperature promoted the formation of 13-cis and 13'-cis and the degradation of 9'-cis. The degradation and formation reactions were found to follow simple first-order kinetics and to be energetically unfavorable, non-spontaneous processes. Arrhenius-type temperature dependence was observed for the degradation of total and all-trans fucoxanthin but not for the reactions of cis isomers. The aerial exposure promoted the oxidative fucoxanthin degradation at 25 °C, whilst illumination caused the initial formation of all-trans, with concurrent sudden degradation of 13-cis and 13'-cis, and the considerable formation of 9'-cis. The fucoxanthin degradation was synergistically promoted when exposed to both air and light.