Comparative Evaluation of the Antioxidant and Anti-Inflammatory Activities of Sargassum horneri Collected from Different Korean Coastal Regions

Sargassum horneri is a brown alga with diverse biological activities; however, the influence of geographical origin on its functional properties remains poorly understood. This study comparatively evaluated the antioxidant and anti-inflammatory activities of S. horneri extracts originating from the East, South, and West Seas of Korea. Total phenolic content (TPC) and total flavonoid content (TFC) were determined, and antioxidant activity was assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging assays and the ferric reducing antioxidant power (FRAP) assay. Anti-inflammatory activity was evaluated in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. The South Sea extract exhibited the highest TPC and showed strong overall antioxidant activity. LPS stimulation reduced cell viability and markedly increased nitric oxide (NO) production, whereas treatment with the regional extracts improved cell viability and suppressed NO production to varying degrees. Among the three extracts, the South Sea extract exhibited the most pronounced inhibitory effect on LPS-induced NO production. Based on its overall bioactivity profile, the South Sea extract was selected for further mechanistic investigation. The extract reduced cyclooxygenase-2 (COX-2) expression and nuclear factor-kappa B (NF-κB) phosphorylation. Furthermore, extracellular signal-regulated kinase (ERK) phosphorylation was markedly reduced, particularly at 400 μg/mL, while c-Jun N-terminal kinase (JNK) phosphorylation showed an overall decreasing tendency at higher concentrations without a strictly concentration-dependent response. In contrast, p38 phosphorylation was not suppressed. These findings suggest that the anti-inflammatory activity of the South Sea S. horneri extract may be associated, at least in part, with modulation of ERK/JNK and NF-κB signaling. Overall, this study demonstrates regional variation in the antioxidant and anti-inflammatory properties of S. horneri and identifies the South Sea-derived extract as a promising marine resource for the development of functional materials.