Cytotoxic effect of xyloglucan and oxovanadium (IV/V) xyloglucan complex in HepG2 cells.

It is well known that the chemical structure of polysaccharides is important to their final biological effect. In this study we investigated the cytotoxic effect of xyloglucan from Copaifera langsdorffii seeds (XGC) and its complex with oxovanadium (XGC:VO) on hepatocellular carcinoma cells (HepG2). After 72 h of incubation, XGC and XGC:VO (200 µg/mL) reduced cell viability in ~20% and ~40%, respectively. At same conditions, only XGC:VO increased in ~20% the LDH enzyme release. In permeabilized cells, incubated with XGC and XGC:VO (200 µg/mL) for 72 h, NADH oxidase activity was reduced by ~45% with XGC and XGC:VO. The succinate oxidase activity was reduced by ~35% with XGC and ~65% with XGC:VO, evidencing that polysaccharide complexation with vanadium could intensify its effects on the respiratory chain. According to this result, the mitochondrial membrane potential was also reduced by ~9% for XGC and ~30% for XGC:VO, when compared to the control group. Interestingly, ATP levels were more elevated for XGC:VO in respect to XGC, probably due the enhance in glycolytic flux evidenced by increased levels of lactate. These results show that the xyloglucan complexation with oxovanadium (IV/V) potentiates the cytotoxic effect of the native polysaccharide, possibly by impairment of oxidative phosphorylation.

Pectin from Brassica oleracea var. italica triggers immunomodulating effects in vivo.

The immunomodulatory ability of pectins is related with structural features such as the degree of methyl-esterification and branching, as well as the molecular mass. The pectin FB, extracted from broccoli stalks (Brassica oleracea var. italica) had low molecular mass, 56% methyl-esterification and galactose as the main neutral sugar, sharing some characteristics with the modified citrus pectin (MCP), which has been extensively studied in vivo and in vitro due its immunomodulator potential. Considering that broccoli has an important role in the diet, the main objective of this study was to investigate the ability of FB in modulating the immune system in vivo. At concentrations 100-500 µg/mL, FB did not affect the viability of macrophages. Evaluations on morphology and phagocytic activity showed that FB (500 µg/mL) increased the number of activated macrophages by 39% and phagocytic activity by 30% within 48 h. FB (200 mg/kg) administered intraperitoneally increased the number of peritoneal macrophages in mice by 490% after 24 h and modulated these cells for an activated phenotype. In mice, oral administration of FB (200 mg/kg) stimulated lymphocytes from spleen and bone marrow proliferation. FB did not induce nitric oxide (NO) production by macrophages and also did not affect the levels of pro-inflammatory interleukins IL-1ß and IL-12 by peritoneal macrophages, but induced the production of the anti-inflammatory interleukin IL-10. The results could suggest that the anti-inflammatory effects triggered by FB could be related to its degree of esterification and pointed this polysaccharide as a target for the development of new immunomodulatory drugs.