Sargassum siliquastrum Aqueous Extract Attenuates Inflammation in RAW 264.7 Macrophages and Modulates Neuroinflammation in D-Galactose-Induced Aging Mice

Inflammation and cellular senescence are fundamental contributors to aging and neurodegenerative disorders. Marine algae are increasingly acknowledged for their content of bioactive molecules capable of influencing inflammation and cellular aging. In this research, we examined the capacity of Sargassum siliquastrum aqueous extract (SSE) to counteract inflammatory responses in RAW 264.7 macrophages stimulated by lipopolysaccharide, as well as aging-related changes in a mouse model of D-galactose (D-gal)-induced aging. SSE treatment markedly lowered levels of pro-inflammatory cytokines, prostaglandin E2, and nitric oxide. Furthermore, SSE attenuated the transcriptional activities of nuclear factor kappa-B (NF-κB) and activator protein 1, while modulating protein expression associated with NF-κB and mitogen-activated protein kinase (MAPK) signaling pathways in RAW 264.7 cells. In vivo, SSE reduced the phosphorylation levels of MAPKs in the hippocampus of D-gal-treated mice. Additionally, SSE modulated the expression of genes associated with cellular senescence and inflammation in the hippocampus and cerebral cortex. However, the apparent molecular effects were not accompanied by significant improvement in passive avoidance performance, which showed only a non-significant trend between the model control and SSE-administrated groups. Collectively, these findings suggest that SSE exerts anti-inflammatory effects in vitro and provide preliminary evidence of its potential to modulate D-gal-induced aging-related neuroinflammatory changes in mice.