Composition of Intracellular and Cell Wall-Bound Phlorotannin Fractions in Fucoid Algae Indicates Specific Functions of These Metabolites Dependent on the Chemical Structure

Abstract

Accumulation of biologically active metabolites is a specific feature of plant biochemistry, directing the use of plants in numerous applications in the pharmaceutical and food industries. Among these substances, the plethora of phenolic compounds has attracted particular interest among researchers. Here, we report on new findings in phlorotannin research, a large group of multifunctional phenolic substances, produced in brown algae. Comprehensive LC-MS profiling of three algal species allowed us to depict the complex pattern of this structurally diverse compound group across different tissues and subcellular compartments. We compiled more than 30 different phlorotannin series in one sample and used accurate mass spectrometry to assign tentative structures to the observed ions based on the confirmed sum formulas. From that, we found that acetylation, hydroxylation, and oxidation are likely to be the most common in vivo modifications to phlorotannins. Using an alternative data mining strategy to cope with extensive coelution and structural isomers, we quantitatively compared the intensity of different phlorotannin series in species, tissues, and subcellular compartments to learn more about their physiological functions. The structure and intra-thallus profiles of cell wall-bound phlorotannins were studied here for the first time. We suggest that one of the major dibenzodioxin-type phlorotannin series may exclusively target integration into the cell wall of fucoid algae.

Chemical Composition and Potential Practical Application of 15 Red Algal Species from the White Sea Coast (the Arctic Ocean)

“…However, our data ( Table 1 ) showed that most of the protein-rich red algae have a relatively low content of total carbohydrates (the only meaningful exception was R. confervoides ). A high amount of phenolics is mostly a problem of brown algae utilization, as they may contain up to 25% DW of specific polyphenols (phlorotannins) [ 41 ]. Red seaweeds typically contain lesser amounts of phenolic compounds than brown and green algae [ 39 ].…”

Seaweed afforestation at large-scales exclusively for carbon sequestration: Critical assessment of risks, viability and the state of knowledge

“…Along temperate rocky shorelines fucoids typically dominate in the intertidal zone, whereas, kelps are more common in the subtidal zone (Chapman, 1987;Lobban and Harrison, 1994). Fucoids generally have slower decomposition rates than kelps because they have more structural tissue and secondary metabolites that may be toxic to grazers and decomposers (Lobban and Harrison, 1994;Lau and Qian, 1997;Nagayama et al, 2002;Birkemeyer et al, 2020). Because of their slower decomposition, the carbon sequestered by fucoids may therefore have a higher likelihood of naturally being deposited in the deep ocean compared to kelps.…”

Concise review of the macroalgal species Pelvetia canaliculata (Linnaeus) Decaisne & Thuret

“…To cleave the permethylated phlorotannins of P. canaliculata, polyhydroxy phenols or biphenyls can be obtained by semi-preparative isolation using sodium in liquid ammonia (Glombitza and Klapperich 1985). A portion of phlorotannins is cell wall-bound and in Pelvetia, this proportion is maximal in the receptacles, where phlorotannins may perform a protective role; by contrast, in Fucus the highest proportion of cell wall-bound phlorotannins occurs in the stipe (Birkemeyer et al 2020).…”