Two Ascophyllum nodosum Fucoidans with Different Molecular Weights Inhibit Inflammation via Blocking of TLR/NF-κB Signaling Pathway Discriminately.

The present study aimed to clarify the potential mechanism of fucoidans found in Ascophyllum nodosum on anti-inflammation and to further explore the relationship between their structures and anti-inflammation. Two novel fucoidans named ANP-6 and ANP-7 and found in A. nodosum , were separated and purified and their structures were elucidated by HPGPC, HPLC, GC-MS, FT-IR, NMR, and by the Congo red test. They both possessed a backbone constructed of →2)-α-L-Fuc p 4 S -(1→, →3)-α-L-Fuc p 2 S 4 S -(1→, →6)-β-D-Gal p -(1→, and →3,6)-β-D-Gal p 4 S -(1→ with branches of →2)-α-L-Fuc p 4 S -(1→ and →3)-β-D-Gal p -(1→. Moreover, ANP-6 and ANP-7 could prevent the inflammation of the LPS-stimulated macrophages by suppressing the NO production and by regulating the expressions of iNOS, COX-2, TNF-α, IL-1β, IL-6, and IL-10. Their inhibitory effects on the TLR-2 and TLR-4 levels suggest that they inhibit the inflammation process via the blocking of the TLR/NF-κB signal transduction. In addition, ANP-6, with a molecular weight (63.2 kDa), exhibited stronger anti-inflammatory capabilities than ANP-7 (124.5 kDa), thereby indicating that the molecular weight has an influence on the anti-inflammatory effects of fucoidans.