Seaweed Phenolics: From Extraction to Applications

Abstract

Seaweeds have attracted high interest in recent years due to their chemical and bioactive properties to find new molecules with valuable applications for humankind. Phenolic compounds are the group of metabolites with the most structural variation and the highest content in seaweeds. The most researched seaweed polyphenol class is the phlorotannins, which are specifically synthesized by brown seaweeds, but there are other polyphenolic compounds, such as bromophenols, flavonoids, phenolic terpenoids, and mycosporine-like amino acids. The compounds already discovered and characterized demonstrate a full range of bioactivities and potential future applications in various industrial sectors. This review focuses on the extraction, purification, and future applications of seaweed phenolic compounds based on the bioactive properties described in the literature. It also intends to provide a comprehensive insight into the phenolic compounds in seaweed.

The Remarkable Antioxidant and Anti-Inflammatory Potential of the Extracts of the Brown Alga Cystoseira amentacea var. stricta

“…The HPLC-MS/MS analysis was performed with the aim of identifying the main molecular components present in the extracts. The analysis of the two extracts showed the same molecular species in both samples and mainly pointed out the presence of meroditerpene-like structures previously described in the same genus [ 26 , 29 , 30 , 31 , 32 ]. In Figure 1 the tandem MS analyses of the 50%-ethanol extract (panel A) and of the DMSO extract (panel B) are shown.…”

“…Besides, the presence of the m / z 191 fragment is related to methyl derivatives of either these nuclei. In conclusion, the HPLC-MS analysis points out that both extracts seem to retrieve the same meroditerpene class of molecules from the algae, confirming the abundance of these bioactive compounds [ 26 , 32 ] in the Cystoseira amentacea Mediterranean seaweed. Therefore, the different efficacy of the two extracts in the various antioxidant and anti-inflammatory tests may be attributable to a quantitative, and not qualitative, difference of the molecules contained.…”

“…In the last twenty years this research allowed the identification of new antioxidant [ 14 , 15 ], anti-inflammatory [ 16 , 17 ] antimicrobial [ 15 ], and anti-tumoral drugs [ 18 ] found in red, green and brown macroalgae. Several studies have recognized brown algae as the most powerful source of natural antioxidants compared to green and red algae, mainly because of their remarkable content in polyphenols and phlorotannins [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. Large brown algae belonging to the orders Laminariales and Fucales, thrive in the intertidal and subtidal rocky reefs worldwide providing food and refuge for many associated species, as well as controlling nutrient cycling and productivity of their habitats.…”

Polyphenols from Brown Seaweeds (Ochrophyta, Phaeophyceae): Phlorotannins in the Pursuit of Natural Alternatives to Tackle Neurodegeneration

“…Phlorotannins are chemically categorized as phloroglucinol (1,3,5-trihydroxybenzene)-based polyphenols and are structurally distinguished according to the type of linkage between the phloroglucinol monomers and the number and distribution of hydroxyl (OH) groups in their molecular backbone. Summarily, phlorotannins can be classified as follows: (i) phlorethols (aryl-ether bonds), (ii) fuhalols (ortho-and para-arranged ether bonds with an additional OH group), (iii) fucols (aryl-aryl bonds), (iv) fucophlorethols (ether and phenyl linkages), (v) eckols (dibenzodioxin elements substituted by a phenoxyl group at C-4), and (vi) carmalols (derivatives of phlorethols with a dibenzodioxin moiety) [36] (Figure 1). Besides playing key roles in different stages of the development of brown seaweeds and acting as algal chemical defenses, a range of bioactive properties have also been reportedly attributed to phlorotannins (as reviewed in [37]).…”

Ocular Delivery of Polyphenols: Meeting the Unmet Needs

“…It is interesting to mention that in addition to terrestrial plants, polyphenols are found in marine microalgae. Compounds such as benzoic acid and vanillic acid are extracted from the genus Gracilaria , while isoflavones such as daidzein or genistein are extracted from red and brown seaweeds [ 17 , 18 ].…”