Extraction and purification of bioactive compounds from sargassum muticum

Laburpena

Sargassum muticum (Yendo) Fensholt is a brown algae native to Japan (Pacific Northwest coast). However, in the Atlantic coasts of Europe and America it is an invasive alga. Invasive species are capable of altering the ecosystem, causing a loss of biodiversity. The presence of Sargassum muticum causes a negative impact on the coast, as it displaces native algae by competing with them for light and nutrients. In addition, fishing and recreational activities are negatively affected. For this reason, different chemical, biological and mechanical methods have been tried in order to eradicate this alga. Based on the lack of success of these strategies, the revalorisation of the brown alga Sargassum muticum is proposed in order to take advantage of its potentially useful bioactive components in cosmetics and pharmaceutical industries. The extraction processes affect to composition, structure and biological activity of the final products. In addition, fractions are more effective than crude extract; however, it is important to maintain the structural integrity to preserve the biological properties. This thesis presents an approach to the utilisation of aqueous extraction processes aided by intensification techniques (ultrasound assisted extraction, microwave hydrogravity and autohydrolysis), both for the direct extraction of the alga and for the depolymerisation of crude fucoidans. The raw material used along the thesis was collected at A Mourisca beach (Pontevedra) in the Summers 2014-2016. The studies carried out in this thesis confirmed the interest of intensified technologies for the extraction and depolymerisation of fucoidan from brown algae, and their potential for the integral valorisation of the components present in the invasive brown alga Sargassum muticum, which could be a source of compounds with interest to the pharmaceutical and cosmetic industries.