AUTHOR=Ktari Leila , Mdallel Cheima , Aoun Brahim , Chebil Ajjabi Leila , Sadok Saloua 

TITLE=Fucoxanthin and Phenolic Contents of Six Dictyotales From the Tunisian Coasts With an Emphasis for a Green Extraction Using a Supercritical CO2 Method

JOURNAL=Frontiers in Marine Science

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2021.647159

DOI=10.3389/fmars.2021.647159

ISSN=2296-7745

ABSTRACT=<p>Dictyotales, a common taxonomic group of brown seaweeds found in warm and temperate waters, are known for their richness in bioactive metabolites. In this study, six species of Dictyotales (<italic>Dictyopteris polypodioides</italic>, <italic>Dictyota dichotoma</italic>, <italic>Dictyota fasciola</italic>, <italic>Dictyota spiralis</italic>, <italic>Padina pavonica</italic>, and <italic>Taonia atomaria</italic>) collected from the Tunisian coasts were investigated for their antioxidant potentials, based on their contents of high added-value bioactive metabolites such as fucoxanthin and polyphenols. Fucoxanthin and polyphenols were analyzed quantitatively by high-performance liquid chromatography (HPLC) and UV spectrophotometer, respectively. The antioxidant property of extracts was also determined based on their ability to scavenge 2,2-Diphenyl-1-picrylhydrazyl (DPPH’s) free radical. Thus, the highest concentrations of fucoxanthin were obtained from <italic>T. atomaria</italic> and <italic>D. polypodioides</italic> (5.53 ± 1.2 and 3.43 ± 1.3 mg⋅g<sup>–1</sup> dry weight, respectively), while the lowest amount was from <italic>D. spiralis</italic> (0.23 ± 0.1 m mg⋅g<sup>–1</sup> dry weight). <italic>Dictyota dichotoma</italic> and <italic>T. atomaria</italic> gave the highest total phenol content (19.3 ± 0.4 and 15.2 ± 1.1 mg GAE⋅g<sup>–1</sup> dry weight, respectively). In the second step, supercritical carbon dioxide (ScCO<sub>2</sub>) was used as a green and environmentally safe technique for the extraction of fucoxanthin from the most abundant species <italic>D. polypodioides</italic>. The extraction of fucoxanthin by ScCO<sub>2</sub> allowed an extraction yield ranging from 0.50 ± 0.04% to 1.32 ± 0.02%, with 60°C temperature and 50-MPa pressure as the best extraction conditions. The maximum fucoxanthin and polyphenol recovery in the extract attained 15 and 64%, respectively. The results strengthen the possible use of Dictyotales from the Mediterranean Sea as a promising source of natural ingredients of health and economic interests contributing to Blue Growth in the region.</p>