Simultaneous extraction and depolymerization of fucoidan from Sargassum muticum in aqueous media.

Elena M Balboa,Sandra Rivas,Herminia Domínguez,Andrés Moure,Juan Carlos Parajó

doi:10.3390/md11114612

Abstract

The biomass components of the invasive seaweed Sargassum muticum were fractionated to allow their separate valorization. S. muticum (Sm) and the solid residue remaining after alginate extraction of this seaweed (AESm) were processed with hot, compressed water (hydrothermal processing) to assess the effects of temperature on fucoidan solubilization. Fucose-containing oligosaccharides were identified as reaction products. Operating under optimal conditions (170 °C), up to 62 and 85 wt% of the dry mass of Sm and AESm were solubilized, respectively. The reaction media were subjected to precipitation, nanofiltration and freeze-drying. The dried products contained 50% and 85% of the fucoidan present in Sm and AESm, respectively; together with other components such as phenolics and inorganic components. The saccharidic fraction, accounting for up to 35% of the dried extracts, contained fucose as the main sugar, and also galactose, xylose, glucose and mannose. The concentrates were characterized for antioxidant activity using the TEAC assay.

Highlights

Sargassum muticum (Yendo) Fensholt is an invasive macroalga living on the Western coasts that causes negative impacts on ecology, fishing and recreational activities
This study provides an assessment on the aqueous processing of raw and alginate extracted Sargassum muticum biomass, with an emphasis on the sugar composition of the solubilized fraction
Crude fucoidan accounted for 4 wt%, in comparison with less than 1 wt% reported for Sargassum sp. [20], 8 wt% for S. muticum [19], and 7–9 wt% for sterile and reproductive tissues of S. pallidum [5]

Summary

Introduction

Sargassum muticum (Yendo) Fensholt is an invasive macroalga living on the Western coasts that causes negative impacts on ecology, fishing and recreational activities. The potential use of the whole alga as a low cost adsorbent for heavy metals’ removal was confirmed [1]. S. muticum has been used as a substrate for hydrothermal processing, yielding a soluble fraction with antioxidant activity and a solid residue with potential as a fertilizer [2]. Marine brown seaweeds contain alginate, laminaran and sulfated polysaccharides known as fucoidans. Fucoidans may differ considerably in composition, molecular mass and structure, depending on the algal species considered [3], geographic location, environmental conditions, harvest season, vegetative and generative life-stages [4] or on the type of tissues sampled [5]. The extraction and purification conditions may affect the polysaccharide composition and structure of the isolated compounds (including charge density, distribution, degree of sulfation, molecular mass and linkage pattern) [6,7]

Methods

Results

Conclusion