Immunomodulatory effects of fucoidan extracted from Sargassum fusiforme in RAW 264.7 macrophages

Sargassum fusiforme, a brown alga, has been traditionally used as an herbal remedy. While previous studies have reported its immunomodulatory properties, the specific immune-modulating effects of fucoidan extracted from S. fusiforme remain underexplored. This study aimed to assess the immune-enhancing properties of S. fusiforme fucoidan (SFF) using the RAW 264.7 macrophage model. SFF significantly increased nitric oxide (NO) production and phagocytic activity at 25–100 μg/mL concentrations, without exhibiting cytotoxicity. RAW 264.7 macrophages treated with SFF adopted a spindle shape with elongated pseudopodia, indicating an activated state. Additionally, SFF upregulated the expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2), while promoting the secretion of cytokines such as tumor necrosis factor-α, interleukin (IL)-6, and IL-1β in a dose-dependent manner. SFF also promoted the activation of nuclear factor kappa B and mitogen-activated protein kinase signaling pathways. These findings suggest that SFF exhibits potent immunomodulatory activity in the RAW 264.7 macrophage model and holds potential as a functional food to support immune health.