Maytenus ilicifolia is a medicinal plant used as a tea (infusion) for treatment of stomach ulcers. This tea furnished a polysaccharide after several purification steps, consisting of a freezing-thawing process, Fehling precipitation, ultrafiltration, and dialysis. It consisted of arabinose, galactose, galacturonic acid, 4-O-methylglucuronic acid, rhamnose, and glucose in a 42:41:6:5:4:2 molar ratio. Methylation analysis, controlled Smith degradation, and NMR spectroscopy indicated that it was a type II arabinogalactan containing a (1-->3)-linked beta-d-Galp main chain, substituted at O-6 by (1-->6)-linked beta-d-Galp chains, which were mainly substituted at O-3 by (1-->5)- and (1-->3)-linked alpha-l-Araf chains, and nonreducing end-units of alpha-l-Araf and 4-O-Me-GlcpA. This polysaccharide significantly inhibited ethanol-induced gastric lesions in rats with an ED(50) of 9.3 mg/kg, suggesting that the arabinogalactan liberated from the infusion has a protective anti-ulcer effect.

Natural polysaccharides have emerged as an important class of bioactive compounds due their beneficial biological effects. Here we investigated the protective and healing effects of rhamnogalacturonan (RGal) isolated from Acmella oleracea (L.) R.K. Jansen leaves in an experimental model of intestinal inflammation in mice and in heterogeneous human epithelial colorectal adenocarcinoma cells (Caco-2). The findings demonstrated that RGal treatment for 7 days reduced the severity of DSS-induced colitis by protecting mice from weight loss, macroscopic damage and reduction of colon length. When compared to the DSS group, RGal also protected the colon epithelium and promoted the maintenance of mucosal enterocytes and mucus secreting goblet cells, in addition to conserving collagen homeostasis and increasing cell proliferation. In an in vitro barrier function assay, RGal reduced the cellular permeability after exposure to IL-1β, while decreasing IL-8 secretion and claudin-1 expression and preserving the distribution of occludin. Furthermore, we also observed that RGal accelerated the wound healing in Caco-2 epithelial cell line. In conclusion, RGal ameliorates intestinal barrier function in vivo and in vitro and may represent an attractive and promising molecule for the therapeutic management of ulcerative colitis.

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