Phlorotannin extracts from Fucales: Marine polyphenols as bioregulators engaged in inflammation-related mediators and enzymes

Phlorotannins are widely recognized as an inexhaustible family of naturally occurring molecules, with great potential in food and pharmaceutical industries. The present work explores the anti-inflammatory activity of phlorotannins from different Fucus species native from the Northern Atlantic coast, and from Fucus vesiculosus Linnaeus grown in an integrated multi-trophic aquaculture (IMTA) system, all scarcely studied regarding these compounds. Purified phlorotannin extracts were evaluated for their toxicity and anti-inflammatory potential in both cell (RAW 264.7 macrophages) and cell-free systems [lipoxygenase (LOX) inhibition and nitric oxide radical (NO) scavenging activity]. Phlorotannin content ranged between 110.28 and 288.36μgofphloroglucinol equivalents(PGE)/100mg dry purified extract (DE), wild species presenting higher content than those from IMTA. Regarding LOX, a strong correlation (r=−0.9118; p<0.0001) between the IC50 values and total phlorotannin content was found, Fucus guiryi G.I. Zardi, K.R. Nicastro, E.S. Serrão & G.A. Pearson exhibiting the best inhibitory capacity (IC50=82.10μg/mL), while F. vesiculosus from IMTA was the less effective (IC50>500μg/mL). Correlation was also observed for NO scavenging (r=−0.6363; p=0.0108). The anti-inflammatory capacity of phlorotannin extracts was further evaluated using RAW 264.7 macrophages stimulated with bacterial lipopolysaccharide, as model of inflammation. The extracts studied were not toxic at the tested concentrations (31.25–500μg/mL). F. vesiculosus from wild origin was the most effective in reducing NO in cell culture medium (IC25=56.52μg/mL), closely followed by other seaweed species under study. The IMTA species was the less effective one (IC25=317.41μg/mL). According to the results obtained, phlorotannin extracts from Fucales arise as potentially beneficial in inflammation-related conditions, effectively acting upon enzymatic and non-enzymatic inflammatory targets.