Methanol Extract of Hydroclathrus clathratus Inhibits Production of Nitric Oxide, Prostaglandin E2 and Tumor Necrosis Factor-α in Lipopolysaccharidestimulated BV2 Microglial Cells via Inhibition of NF-kB Activity

Purpose: Hydroclathrus clathratus is a brown marine seaweed known to possess anti-cancer, anti-herpetic, and anti-coagulant activities. The present study is aimed at investigating some anti-inflammatory effects of H. clathratus. Methods: We investigated the anti-inflammatory effects of the methanol extract of H. clathratus (MEHC) by expression of mRNA and protein using RT-PCR and Western blot analysis in lipopolysaccharide (LPS)-stimulated BV2 microglial cells. The level of nitric oxide (NO) production was analyzed using Griess reaction. The release of prostaglandin E2 (PGE2) and tumor necrosis factor-α (TNF-α) were determined using sandwich ELISA. NF-kB activation was detected using EMSA methods. Results: The results obtained indicate that the extract (MEHC) inhibited LPS-induced NO, PGE2, and TNF-α production without any significant cytotoxicity (p 0.05). MEHC also inhibited production of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2) and TNF-α mRNA in LPS-stimulated BV2 microglial cells. In addition, MEHC significantly reduced (p 0.05) nuclear translocation of the nuclear factor-kB (NF-kB) subunits, p50 and p65, and its DNA-binding activity in LPS-stimulated BV2 microglial cells. Conclusion: These results suggest that MEHC suppresses the induction of TNF-α, as well as iNOS and COX-2 expression, by blocking LPS-induced NF-kB activation.