Migration and proliferation of cancer cells in culture are differentially affected by molecular size of modified citrus pectin.

While chemically and thermally modified citrus pectin (MCP) has already been studied for health benefits, it is unknown how size-fractionated oligo- and polysaccharides differentially affect cancer cell behavior. We produced thermally MCP and fractionated it by molecular size to evaluate the effect these polymers have on cancer cells. MCP30/10 (between 30 and 10 kDa) had more esterified homogalacturonans (HG) and fewer rhamnogalacturonans (RG-I) than MCP and MCP30 (higher than 30 kDa), while MCP10/3 (between 10 and 3 kDa) showed higher amounts of type I arabinogalactans (AGI) and lower amounts of RG-I. MCP3 (smaller than 3 kDa) presented less esterified HG and the lowest amount of AGI and RG-I. Our data indicate that the enrichment of de-esterified HG oligomers and the AGI and RG-I depletions in MCP3, or the increase of AGI and loss of RGI in MCP30/10, enhance the anticancer behaviors by inhibiting migration, aggregation, and proliferation of cancer cells.

Polysaccharides from chayote enhance lipid efflux and regulate NLRP3 inflammasome priming in macrophage-like THP-1 cells exposed to cholesterol crystals.

The contribution of dietary fiber to decrease the risk of atherosclerosis may occur through other mechanisms besides the increased excretion of cholesterol. Although macrophages are crucial for lipid clearance, the excessive uptake of cholesterol crystals (CC) by these cells induce NLRP3 inflammasome and foam cell formation. Thus, we investigated whether the water-soluble DF from chayote (WSP) regulate CC-pretreated macrophage-like THP-1 cells. Linkage analysis indicated that WSP is composed mainly of pectic homogalacturonan and highly branched type I rhamnogalacturonan as well as hemicellulosic material including glucomannan, xyloglucan, and glucurono(arabino)xylan. WSP reduced interleukin (IL)-1ß and chemokine release in CC-pretreated macrophages. Notably, WSP also reduced lipid accumulation in cells previously exposed to CC. Furthermore, WSP upregulated liver X receptor alpha expression, which may account for increased lipid efflux, and reduced matrix metallopeptidase 9 expression. WSP also reduced active caspase-1 protein levels, and downregulated NLRP3 and IL-1ß gene expression in CC-pretreated cells, suggesting that this polysaccharide fraction regulates the priming signals required for NLRP3 inflammasome activation. Thus, WSP regulate lipid efflux and suppress inflammasome priming in macrophages, suggesting that the health benefits of this dietary fiber could go beyond its physical properties on the gastrointestinal tract.

Ripening-induced chemical modifications of papaya pectin inhibit cancer cell proliferation.

Papaya (Carica papaya L.) is a fleshy fruit with a rapid pulp softening during ripening. Ripening events are accompanied by gradual depolymerization of pectic polysaccharides, including homogalacturonans, rhamnogalacturonans, arabinogalactans, and their modified forms. During intermediate phases of papaya ripening, partial depolymerization of pectin to small size with decreased branching had enhanced pectin anti-cancer properties. These properties were lost with continued decomposition at later phases of ripening. Pectin extracted from intermediate phases of papaya ripening markedly decreased cell viability, induced necroptosis, and delayed culture wound closing in three types of immortalized cancer cell lines. The possible explanation for these observations is that papaya pectins extracted from the third day after harvesting have disrupted interaction between cancer cells and the extracellular matrix proteins, enhancing cell detachment and promoting apoptosis/necroptosis. The anticancer activity of papaya pectin is dependent on the presence and the branch of arabinogalactan type II (AGII) structure. These are first reports of AGII in papaya pulp and the first reports of an in vitro biological activity of papaya pectins that were modified by natural action of ripening-induced pectinolytic enzymes. Identification of the specific pectin branching structures presents a biological route to enhancing anti-cancer properties in papaya and other climacteric fruits.

The water-soluble non-starch polysaccharides from bananas display immunomodulatory properties on cultured macrophages.

Some diet components, such as certain indigestible polysaccharides from edible plants, may interact with the gut-associated lymphoid tissue and improve the host immune response to pathogens. The non-starch polysaccharides (NSP) from bananas are non-digestible carbohydrates that resemble some immunomodulatory polysaccharides occurring in the cell wall of cereals. Based on this similarity, the effects of the water-soluble NSP from two banana cultivars (Nanicão and Thap Maeo) on the phagocytic activity, nitric oxide (NO) and cytokines produced by cultured macrophages were investigated. An investigation into the monosaccharide composition and the oligomers released by enzymatic hydrolysis of the ultra-filtered fraction above 50kDa and the heat-treated fraction of water-soluble NSP from both cultivars revealed they are mostly composed of mannan and galacturonans (homogalacturonan, xylogalacturonan and rhamnogalacturonan). The NSP tested were able to activate the macrophages, but the effects on the phagocytic activity and the release of tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6) and nitric oxide production were dependent on the polysaccharide concentration and the cultivar origin. Despite some specific differences, the NSP from Nanicão and Thap Maeo banana fruits may be considered prospective food immunomodulators, which contribute to the promotion of a more responsive immune system.

Changes in cell wall composition associated to the softening of ripening papaya: evidence of extensive solubilization of large molecular mass galactouronides.

Papaya (Carica papaya) is a climacteric fruit that undergoes dramatic pulp softening. Fruits sampled at three different conditions (natural ripening or after exposition to ethylene or 1-methylcyclopropene) were used for the isolation of cell wall polymers to find changes in their degradation pattern. Polymers were separated according to their solubility in water, CDTA, and 4 M alkali, and their monosaccharide compositions were determined. Water-soluble polymers were further characterized, and their increased yields in control and ethylene-treated fruit, in contrast to those that were treated with 1-MCP, indicated a strong association between fruit softening and changes in the cell wall water-soluble polysaccharide fraction. The results indicate that the extensive softening in the pulp of ripening papayas is a consequence of solubilization of large molecular mass galacturonans from the pectin fraction of the cell wall. This process seems to be dependent on the levels of ethylene, and it is likely that the releasing of galacturonan chains results from an endo acting polygalacturonase.

Participação dos polissacarídeos de parede celular no fenômeno de endurecimento de feijões (Phaseolus vulgaris L) - cv Carioca-Pérola / Participation of the polysaccharide of cellular wall in the phenomenon of beans hardening (Phaseolus vulgaris L) cv Carioca-Perola

O feijão é um alimento nutritivo amplamente consumido no Brasil, porém, apresenta facilidade para desenvolver o defeito textural hard-to-cook (HTC) que torna as sementes resistentes ao amaciamento por cocção e provoca perdas econômicas e nutricionais. A maciez, um atributo importante nos grãos, proporciona melhor aceitabilidade do produto pelo consumidor, melhor qualidade nutricional e organoléptica e menor gasto de tempo e combustível no preparo. Devido à importância da parede celular na textura dos alimentos, foram investigadas alterações na estrutura e composição de seus polissacarídeos causada pelo HTC...