Elena M. Balboa

In vitro antioxidant properties of crude extracts and compounds from brown algae

Research on the bioactives from seaweeds has increased in recent years. Antioxidant activity is one of the most studied, due to the interest of these compounds both as preservatives and protectors against oxidation in food and cosmetics and also due to their health implications, mainly in relation to their potential as functional ingredients. Brown algae present higher antioxidant potential in comparison with red and green families and contain compounds not found in terrestrial sources. In vitro antioxidant chemical methods, used as a first approach to evaluate potential agents to protect from lipid oxidation in foods, confirmed that the brown algae crude extracts, fractions and pure components are comparatively similar or superior to synthetic antioxidants. Particular emphasis on the fucoidan and phlorotannin polymeric fractions is given, considering variations associated with the species, collection area, season, and extraction and purification technologies.

Simultaneous Extraction and Depolymerization of Fucoidan from Sargassum muticum in Aqueous Media

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.

Valorization of Sargassum muticum Biomass According to the Biorefinery Concept.

The biorefinery concept integrates processes and technologies for an efficient biomass conversion using all components of a feedstock. Sargassum muticum is an invasive brown algae which could be regarded as a renewable resource susceptible of individual valorization of the constituent fractions into high added-value compounds. Microwave drying technology can be proposed before conventional ethanol extraction of algal biomass, and supercritical fluid extraction with CO2 was useful to extract fucoxanthin and for the fractionation of crude ethanol extracts. Hydrothermal processing is proposed to fractionate the algal biomass and to solubilize the fucoidan and phlorotannin fractions. Membrane technology was proposed to concentrate these fractions and obtain salt- and arsenic-free saccharidic fractions. Based on these technologies, this study presents a multipurpose process to obtain six different products with potential applications for nutraceutical, cosmetic and pharmaceutical industries.

Comparative environmental assessment of valorization strategies of the invasive macroalgae Sargassum muticum

The invasive brown seaweed Sargassum muticum (Yendo) exhibits a significant content of phenolic compounds, polysaccharides and fucoxanthin, with potential biological activities. In this study, four valorization strategies for S. muticum biomass were compared under a life cycle perspective. Depending on the alternative, three products were obtained: sodium alginate, antioxidant extract and fucoxanthin-containing extract. Regardless of the approach, the combined extraction of alginate and antioxidant from wet algae constituted the most efficient scenario. Among the stages, supercritical extraction of fucoxanthin and non-isothermal autohydrolysis were identified as the major environmental burdens due to electricity consumption. Although changes in product distribution fairly affected the environmental impacts of the scenarios, the single extraction of antioxidant fraction and the integral valorization to obtain fucoxanthin, alginate and antioxidant were only competitive when considering a functional unit based on the value of the products through an economic allocation approach instead of the amount of valorized algae.

Cosmetics from Marine Sources

The application of marine resources for the formulation of cosmetics has been known for centuries. Marine organisms produce unique compounds, which are not found in terrestrial sources, to provide protection against hard environmental conditions. They have been used both to confer:

Erythrocytes and cell line-based assays to evaluate the cytoprotective activity of antioxidant components obtained from natural sources.

Oxidative stress can damage cellular components including DNA, proteins or lipids, and may cause several skin diseases. To protect from this damage and addressing consumers appeal to natural products, antioxidants obtained from algal and vegetal extracts are being proposed as antioxidants to be incorporated into formulations. Thus, the development of reliable, quick and economic in vitro methods to study the cytoactivity of these products is a meaningful requirement. A combination of erythrocyte and cell line-based assays was performed on two extracts from Sargassum muticum, one from Ulva lactuca, and one from Castanea sativa. Antioxidant properties were assessed in erythrocytes by the TBARS and AAPH assays, and cytotoxicity and antioxidant cytoprotection were assessed in HaCaT and 3T3 cells by the MTT assay. The extracts showed no antioxidant activity on the TBARS assay, whereas their antioxidant capacity in the AAPH assay was demonstrated. On the cytotoxicity assays, extracts showed low toxicity, with IC50 values higher than 200μg/mL. C. sativa extract showed the most favourable antioxidant properties on the antioxidant cytoprotection assays; while S. muticum and U. lactuca extracts showed a slight antioxidant activity. This battery of methods was useful to characterise the biological antioxidant properties of these natural extracts.

Study of the seasonal variation on proximate composition of oven-dried Sargassum muticum biomass collected in Vigo Ria, Spain

AbstractSamples of the invasive brown alga Sargassum muticum from Vigo Ria, Galicia (NW Spain), were oven-dried. Currently, this drying technique is a regular process in local seaweed industry. Samples collected monthly were studied for proximal composition. Variables were investigated for statistical analysis correlation with environmental parameters (temperature, relative humidity, precipitation index) to detect significant seasonal variations. Even though thermal treatment affected phenolic extractability, an interesting content in minerals and fatty acids was found. Besides, variables with higher seasonal correlation were total extractibles (2.3–6.9, 0.3–5.9 and 0.6–4.1xa0%, for ethanol, ethylacetate and hexane extracts, respectively), protein (7–11xa0%), C (33.8–43.8xa0%), Mn (47.9–12.1xa0mgxa0kg−1), Zn (12.7–40.8xa0mgxa0kg−1) and Cu (8–23xa0mgxa0kg−1), neutral detergent fibre (27.9–44.5xa0%), acid-insoluble residue (20–36xa0%), total lipid percent (1.6–3.2xa0%), monounsaturated and polyunsaturated fatty acids (22.5–36.1 and 20.1–31.8xa0%) and ω6/ω3 ratio (1.4–3.4). Hence, seasonal characterization constitutes a preliminary step for future valorization of algal biomass as ingredient in feed supplements or fertilizers.n Graphical Abstractᅟ

Algal proteins, peptides and amino acids.

Abstract: In this chapter data on the composition of proteins, peptides and amino acids from macro and microalgae are presented. The specific chemical and physicochemical methods of protein and amino acid analysis are discussed. Information on the variability in the contents and activities caused by seasonal and environmental factors is described. In addition, the biological activities and the potential applications as functional food ingredients are discussed.