Dietary fibres from guavira pomace, a co-product from fruit pulp industry: Characterization and cellular antioxidant activity.

Exotic fruits and their co-products may be valuable sources of antioxidant dietary fibres (DF) which are useful for food industry and human health. In this study, we aimed to characterize DF obtained from guavira fruit pomace and investigate its antioxidant potential employing TEAC assay as well as a cell model. The DF were chemically characterized as containing arabinan, highly-methoxylated homogalacturonan and arabinogalactan. The DF-containing fraction (CPW) presented ABTS free radical scavenger activity. MTT and DCFH-DA assay were performed to assess, respectively, changes in cell viability and the potential intracellular antioxidant activity against H2O2-induced oxidative stress in murine NIH 3T3 fibroblast. CPW exhibited no effects on cell viability, moreover, when administered 48 h prior the induction of H2O2 toxic effects, it protected the cells, significantly increasing the cell viability compared to control. This protection may be related to the observed reduction of reactive oxygen species levels. Thus, the pre-treatment of cells with guavira DF for 48 h remarkably induced a cytoprotection against pro-oxidant conditions, and may be a valuable functional compound recovered from an unexploited agroindutrial waste.

Cytotoxic effect of crude and purified pectins from Campomanesia xanthocarpa Berg on human glioblastoma cells.

A new source of pectin with a cytotoxic effect on glioblastoma cells is presented. A homogeneous GWP-FP-S fraction (Mw of 29,170 g mol-1) was obtained by fractionating the crude pectin extract (GW) from Campomanesia xanthocarpa pulp. According to the monosaccharide composition, the GWP-FP-S was composed of galacturonic acid (58.8%), arabinose (28.5%), galactose (11.3%) and rhamnose (1.1%), comprising 57.7% of homogalacturonans (HG) and 42.0% of type I rhamnogalacturonans (RG-I). These structures were characterized by chromatographic and spectroscopic methods; GW and GWP-FP-S fractions were evaluated by MTT and crystal violet assays for their cytotoxic effects. Both fractions induced cytotoxicity (15.55-37.65%) with concomitant increase in the cellular ROS levels in human glioblastoma cells at 25-400 µg mL-1, after 48 h of treatment, whereas no cytotoxicity was observed for normal NIH 3T3 cells. This is the first report of in vitro bioactivity and the first investigation of the antitumor potential of gabiroba pectins.

Structure and intracellular antioxidant activity of pectic polysaccharide from acerola (Malpighia emarginata).

Malpighia emarginata is a tropical fruit plant, found naturally in the Caribbean islands and South America that produces an edible fruit known as acerola or Barbados Cherry. Its polysaccharides were obtained by aqueous extraction, subjected to a freezing and thawing process and ultrafiltration. A homogeneous fraction (ACWS-01E) was analyzed by sugar composition, HPSEC, methylation and NMR spectroscopy analyses. The results showed an arabinan-rich pectic polysaccharide, with 6.1×104g/mol and formed mainly by a high methyl esterified (DM=86%) homogalacturonan and branched arabinan. This latter is anchored in type I rhamnogalacturonan regions. The main chain of arabinan consisted of (1→5)-linked α-Araf, branched only at O-3. The potential ACWS-01E intracellular antioxidant activity against H2O2-induced oxidative stress in murine fibroblast cell line (3T3) was determined by DCFH-DA assay. The treatment with ACWS-01E significantly reduced H2O2-induced cytotoxic effect and the levels of reactive oxygen species (ROS). These findings suggested that ACWS-01E protected and improved NIH 3T3 cell viability from H2O2-induced toxicity by decreasing intracellular levels of ROS.