First Insight into the Neuroprotective and Antibacterial Effects of Phlorotannins Isolated from the Cell Walls of Brown Algae Fucus vesiculosus and Pelvetia canaliculata

Abstract

Phaeophyceae (brown algae) essentially contribute to biotopes of cold and temperate seas. Their thalli are rich in biologically active natural products, which are strongly and universally dominated with phlorotannins—polyphenols of complex and diverse structure based on multiple differently arranged phloroglucinol units and well known as strong antioxidants with a broad spectrum of biological activities. In the algal cells, phlorotannins can either accumulate in the cytoplasm or can be secreted into the cell wall (CW). The biological activities of extractable intracellular phlorotannins have been comprehensively characterized, whereas the properties of the CW-bound polyphenol fraction are still mostly unknown. Recently, we identified dibenzodioxin bonding as the principal structural feature of the CW-bound phlorotannins in fucoid algae, whereas soluble intracellular phlorotannins rely on aryl and ether bonds. However, profiles of biological activity associated with these structural differences are still unknown. Therefore, to the best of our knowledge, for the first time we address the antioxidant, cytotoxic, neuroprotective, and antibacterial properties of the CW-bound phlorotannin fractions isolated from two representatives of the order Fucales—Fucus vesiculosus and Pelvetia canaliculata. The CW-bound phlorotannins appeared to be softer antioxidants, stronger antibacterial agents and were featured with essentially less cytotoxicity in comparison to the intracellular fraction. However, the neuroprotective effects of both sub-cellular phlorotannin fractions of F. vesiculosus and P. canaliculata were similar. Thus, due to their lower cytotoxicity, CW-bound phlorotannins can be considered as promising antioxidants and neuroprotectors.

Metabolic Adjustment of High Intertidal Alga Pelvetia canaliculata to the Tidal Cycle Includes Oscillations of Soluble Carbohydrates, Phlorotannins, and Citric Acid Content

“…Notably, only the intracellular fraction of phlorotannins, but not the CW-bound one, increased in the air-exposed Pelvetia cells (Figure 6). This corresponds well to the results of our previous studies, where we showed that these two subcellular pools of phlorotannins differ in their molecular composition, and that free radical scavenging activity of the CW-bound phlorotannins of P. canaliculata is substantially lower compared to that of the intracellular phlorotannins [60,61]. Generally, among studied fucoid algae, P. canaliculata is distinguished by its unusually complex phlorotannin profile, which was suggested to reflect both adaptation of this species to high intertidal conditions and interaction with the endophyte fungus [60,62].…”

Natural Bioactive Compounds from Macroalgae and Microalgae for the Treatment of Alzheimer’s Disease: A Review

“…These results suggest that they may be useful as effective antioxidants in neurodegenerative diseases like AD, where oxidative stress plays a crucial role in disease progression. Phlorotannins were recently extracted from the cell walls of Pelvetia canaliculate and Fucus vesiculosus to examine their antioxidant and neuroprotective effects on cell culture models of AD and Parkinson’s Disease (PD) [ 41 ]. These cell wall-bound phlorotannins demonstrated comparable neuroprotective effects to their intracellular fractions, with less cytotoxicity but milder antioxidant activity, indicating that they may be promising candidates for therapeutic applications in neurodegenerative diseases [ 41 ].…”

“…Phlorotannins were recently extracted from the cell walls of Pelvetia canaliculate and Fucus vesiculosus to examine their antioxidant and neuroprotective effects on cell culture models of AD and Parkinson’s Disease (PD) [ 41 ]. These cell wall-bound phlorotannins demonstrated comparable neuroprotective effects to their intracellular fractions, with less cytotoxicity but milder antioxidant activity, indicating that they may be promising candidates for therapeutic applications in neurodegenerative diseases [ 41 ]. On the other hand, phlorotannins isolated from brown seaweed, such as eckol, dieckol, and bieckol, have been shown to have anti-inflammatory properties.…”

Marine Macroalgae Polyphenols as Potential Neuroprotective Antioxidants in Neurodegenerative Diseases

“…The recent study of Meshalkina et al [ 103 ] assessed the anti-neurodegenerative activity of phlorotannin extracted from F. vesiculosus and Pelvetia canaliculata for differentiated SH-SY5Y cells. The extracts of both brown algae showed modest but significant protective effects in the paraquat cell model of PD.…”