Functional Evaluation of Fucus vesiculosus Extract: Bioactivity Retention After In Vitro Digestion and Anti-Inflammatory Effects on Murine Peritoneal Macrophages

Background: Nowadays, to improve animal production sustainably, the zootechnical sector is exploring novel, functional ingredients, such as seaweed. This study investigated the functional properties of Fucus vesiculosus and their persistence after simulated digestion. Methods: F. vesiculosus was nutritionally characterized (AOAC methods) and digested in vitro through the INFOGEST protocol. The polyphenol, flavonoid, and phlorotannin con- tents of the samples were analyzed through colorimetric assays. The antioxidant properties were evaluated using ABTS assay and the growth inhibition capacity against Escherichia coli using the microdilution method. The cytotoxic activity and anti-inflammatory properties were evaluated on mouse peritoneal macrophages using crystal violet assay and the gene expression of IL-1β, IL-6, TNF-α, and iNOS. Results: F. vesiculosus demonstrated high levels of dietary fiber (47.36%) and protein (13.99%). Significant levels of polyphenols (6428.98 μg TAE/g), flavonoids (5171.31 μg CE/g), and phlorotannins (2.10 mg PGE/g) were detected. These bioactive compounds allowed for strong antioxidant activity (85.96% ABTS+ scav- enging) and E. coli growth inhibition (17%). Simulated digestion minimally impacted the content of bioactive compounds and their associated functional properties. F. vesiculosus exhibited a protective effect against oxidative stress in macrophages, downregulating pro- inflammatory cytokines (IL-1β, IL-6, and TNF-α). Conclusions: These findings support the potential of F. vesiculosus as a functional feed ingredient for livestock, maintaining its beneficial properties even after digestion.