Abstract: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.
A method is described for the simultaneous determination of residues of five fungicides used for foliar treatment of apple and pear trees, and for postharvest application. After extraction, the mixture of these fungicides is cleaned‐up on a ‘SEP PAK C18’ cartridge and the components determined by gas‐liquid chromatography with electron‐capture detection. The minimum detectable amounts in apples and pears, on a fresh weight basis, were 0.005mg kg−1 for vinclozolin, 0.010mg kg−1 for captan, folpet and iprodione, and 0.020 mg kg−1 for captafol. The percentage recovery for each fungicide (calculated by analysing four samples of untreated apples and pears, to which varying concentrations of each active ingredient had been added) varied for vinclozolin between 70.0 and 89.2, for captan between 72.0 and 83.8, for folpet between 73.0 and 93.0, for captafol between 70.8 and 91.8, and for iprodione between 75.1 and 97.1.
Studies have evidenced the biological properties of fucoxanthin and the commercialisation of various nutritional supplements based on seaweed extracts that claim high fucoxanthin content is constantly growing. However, it was demonstrated that fucoxanthin is highly susceptible to degradation, and in this context the need for simple and reliable analytical methods for fucoxanthin analysis is evident. This article presents a simple thin-layer chromatography (TLC) densitometric method for the determination of fucoxanthin from Undaria pinnatifida extracts and commercial formulations. Fucoxanthin was separated on TLC silica gel 60 F254 plates with acetone:n-hexane 6:4 v/v as mobile phase. Densitometric analysis was performed using the Image J image-processing program available online. Calibration data revealed good linear relationship (R(2) = 0.9955) between peak area and concentration of fucoxanthin. The repeatability was 2.0 (% CV), and intra-day and inter-day precisions were 1.5 and 2.0 (% RSD), respectively. The proposed method provides an inexpensive tool in preliminary evaluation of fucoxanthin-based products.
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