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

摘要

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-alpha) 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.