Simultaneous extraction and purification of fucoxanthin from Tisochrysis lutea microalgae using compressed fluids

The marine microalga Tisochrysis lutea, a Haptophyta with a thin cell wall and currently used mainly in aquaculture is a potential source of several bioactive compounds of interest such as carotenoids. In the present study, the simultaneous extraction and purification of fucoxanthin, the main carotenoid from T. lutea, was optimized using pressurized fluid extraction followed by in-cell purification. An experimental design was employed to maximize carotenoids' extraction; the experimental factors chosen were: (i) percentage of ethanol/ethyl acetate (0-100 %), (ii) temperature (40-150°C), and (iii) number of static extraction cycles (1-3). The maximum carotenoids' recovery, mainly fucoxanthin, was obtained with pure ethyl acetate at 40°C using one extraction cycle, achieving values of 132.8 mg of carotenoids per gram of extract. Once the optimum extraction conditions were confirmed, in-cell purification strategies using different adsorbents were developed to obtain fucoxanthin-enriched extracts. Activated charcoal showed potential retention of chlorophylls allowing an effective purification of fucoxanthin in the obtained extracts. Chemical characterization of extracts was carried out by reversed-phase high-performance liquid chromatography with diode array detection. Therefore, a selective fractionation of high value compounds was achieved using the proposed green downstream platform based on the use of compressed fluids.