A fucan of a brown seaweed and its antitumoral property on HT-29 and immunomodulatory activity in murine RAW 264.7 macrophage cell line

Abstract

Polysaccharides from algae are also proper candidates with therapeutic properties and immunomodulatory and antitumor effects. The brown seaweed Lobophora variegata synthesizes different groups of anionic polysaccharides with several biological properties. Sulfated polysaccharides were obtained by delipidation of seaweed, proteolysis, and fractionation with different volumes of acetone. A fraction of sulfated polysaccharides, fucans or fucoidans, was extracted with 0.8 v acetone and named L. variegata (LV). This fucan was assessed in the inflammatory process in rats, antitumor action on human colon adenocarcinoma (HT-29 cells), apoptosis, and its effect on the cell cycle. LV fraction, a galactofucan, exhibited a high ratio of total sugar/sulfate (1.5) and a very low level of proteins. This polysaccharide showed an antiinflammatory effect on two models of inflammation induced by croton oil and oxazolone in rats. LV was analyzed in cellular proliferation of HT-29. We also demonstrated the cytotoxic action against this cell line and induction in the apoptosis and decreased the cell cycle in phases S and G 2 /M and the accumulation of cells in the G 1 phase. Our studies with LV showed a marked immunomodulatory action without and with lipopolysaccharide (LPS) on RAW 264.7 cells. Comparative studies of two fucans, LV and FV (Fucus vesiculosus), with different structures were assessed on viability in macrophages, RAW 264.7 cells. Both showed cytotoxicity in these cells. We observed high levels of nitric oxide (NO) production, interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) when treated at 0.25, 0.5, and 1.0 mg mL −1 of LV. Data also suggest that LV has potential antitumor effects on HT-29 and antiinflammatory and immunomodulatory effects on RAW 264.7 cells.

Sulfated Galactofucans: An Outstanding Class of Fucoidans with Promising Bioactivities

“…Galactofucans from Sargassum wightii showed superior activity to aspirin, with EC 90 values ranging from 0.2 to 1.22 mg/mL for inhibition of inflammatory-related enzymes [ 92 , 93 ]. Only the galactofucans from Saccharina japonica and Lobophora variegata have been tested in vivo with positive results [ 42 , 65 , 70 , 104 ]. Chen et al showed that the investigated galactofucans from S. japonica were non-cytotoxic in the range of 3.125 to 25 μg/mL [ 65 ].…”

“…The immunomodulatory and anticomplement properties of galactofucans have been explored recently. Galactofucans from Saccharina japonica and Lobophora variegata exhibited immune-modulatory effects on RAW 264.7 cells (monocyte/macrophage-like cells) [ 70 , 102 ]. Studies on S. japonica and Sargassum fusiforme suggested that sulfated galactofucans were the active components of the anticomplement activity, with IC 50 values of 4.5 and 5.5 µg/mL, respectively [ 81 ].…”