In vitro bioactive properties of phlorotannins recovered from hydrothermal treatment of Sargassum muticum

• S. muticum phlorotannins solubilized in autohydrolysis were recovered by adsorption.
• 70% phlorotannins adsorbed and 80% desorbed with ethanol solutions in dynamic assays.
• Desorbed products showed antiproliferative action on lung and colon carcinoma cells.
• Desorbed products inhibited human neutrophils’ oxidative burst and PGE2 production.

The present work addresses the potential of different adsorbents for the recovery of the phlorotannin fraction present in the liquid phase from the autohydrolysis of Sargassum muticum. Operating with the extract generated during autohydrolysis of alginate exhausted algae, the kinetics followed pseudo-second order and the equilibrium corresponded to Freundlich model. In batch configuration, up to 70% phlorotannins were adsorbed and up to 30% were desorbed with ethanolic solutions. Comparable performance was observed with the autohydrolysis extracts from the whole algae. The phloroglucinol content, the reducing and ABTS antiradical capacities of the desorbed product increased by 2–4 times in relation to the values in the autohydrolysis extracts. Dynamic elution with 68% ethanol allowed 80% desorption and provided a concentrated extract with antiradical capacity equivalent to 1 g Trolox/g extract. This product showed anti-proliferative properties against lung adenocarcinoma A549 cells and against colon carcinoma HCT-116 cells. It also inhibited the production of reactive oxygen species by human neutrophils and inhibited prostaglandin E2 production via cyclooxygenase-2 in human whole blood.