Browsing by Subject "polyphenols"
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Item Anti-inflammatory and Cytotoxic Activities of Mango (Mangifera indica L. var Keitt) Polyphenols in Cancer and Non-cancer Breast Fibroblasts in Vitro(2013-08-12) Arbizu Berrocal, ShirleyBreast cancer is the leading cause of cancer death among women worldwide and polyphenols are under investigation as an alternative to conventional treatment approaches of breast cancer. The anti-inflammatory and anti-proliferative activities of polyphenols have been demonstrated in many studies, yet cellular targets and the underlying cellular mechanisms remain unclear. The overall goal of this study was to investigate the anti-inflammatory and cytotoxic properties of polyphenol compounds extracted from the mango variety Keitt in MCF-12A breast non-cancer and MDA-MB231 breast cancer cells by assessing the modulation of signaling pathways involved in inflammation and carcinogenesis. Mango polyphenols were identified by HPLC-MS analysis. The generation of reactive oxygen species was performed using fluorescence intensity in the DCFH-DA assay. Gene expression was analyzed by qRT-PCR, and protein expression was conducted by Western Blotting and Multiplex Bead assay analysis. Bioactive compounds identified in the mango pulp by HPLC-MS included a great variety of polyphenols such as gallic acid, galloyl glucosides with different degree of polymerization and other polyphenols. The anti-inflammatory activities of mango polyphenols were evaluated in MCF-12A non cancer breast fibroblasts. An inflammatory microenvironment for MCF-12A breast cells was induced with tumor necrosis factor alpha (TNF-?). The generation of reactive oxygen species was suppressed significantly compared to cells induced with TNF-?, where there was no significant difference between the concentrations of mango polyphenol extract. Results showed a significant down-regulation of mRNA and protein expression of inflammatory genes involved in the PI3K/AKT pathway and related downstream targets such as NF-?B and mTOR involved in biological processes including cell growth, proliferation and survival. Moreover, mango polyphenols had a significant impact on the miRNA-126-PI3K/AKT axis which plays an important role in inflammation and carcinogenesis, suggesting a potential anti-inflammatory underlying mechanism. The cytotoxic effects of mango polyphenols were investigated in MDA-MB231 breast cancer cells. Mango polyphenols decreased the production of reactive oxygen species; however no significant differences were found between the tested concentrations of mango polyphenols. The gene expression of proapoptotic factors involved in the intrinsic mitochondrial pathway such as cytochrome C and caspase-3 were significantly regulated after mango polyphenol treatment. In addition, the suppression of the PI3K/AKT/mTOR pathway and downstream effectors such as HIF-1? and VEGF as well as the disruption of the miRNA-21-PTEN/AKT axis were identified as potential underlying mechanism of the cytotoxic properties of mango polyphenols. Overall, findings from this study show that mango polyphenols counteract inflammatory and cancerous cell signaling processes; therefore the potential of mango polyphenols in the prevention of breast-cancer focusing on the PI3K/AKT/mTOR-axis should be further investigated.Item Diet, Disease State, and the Space Environment Modify the Intestinal Microbiota and Mucosal Environment via Microbiota-directed Alterations in Colonocyte Signalling(2013-11-25) Ritchie, Lauren EMicrobial dysbiosis and toll-like receptor (TLR) signaling play a role in colonic injury and inflammation. Ulcerative colitis and radiation are known to alter microbiota, and diets containing polyphenols impact bacterial populations. We hypothesized that diet can mitigate dextran sodium sulfate (DSS) colitis (sorghum bran diets containing polyphenols) and space environment-induced alterations (normal iron content) in colonic microbiota and TLR signaling. To test this we utilized two experimental paradigms; DSS-induced colitis (3% DSS, 48-hr, 3 exposures, 2 wk separation), and three models to emulate the space environment: 1) fractionated low linear energy transfer (LET) ? radiation (RAD) (3 Gy) and high Fe diet (IRON) (650 mg/kg), 2) high LET Si particle exposure (50 cGy) and 1/6 G hind limb unloading (HLU), and 3) 13 d spaceflight. Bran diets upregulated proliferation, and repair protein (TFF3 and TGF?) and short chain fatty acid (SCFA) transporter (Slc16a1 and Slc5a8) expression post-DSS. Diet significantly affected 24-hr fecal butyrate production, with Cellulose and Black bran having numerically higher concentrations. Two predominant phyla were identified, Firmicutes and Bacteroidetes, and this ratio was higher in Cellulose DSS. Post DSS#3 the proportion of Bacteroidales, Clostridiales, and Lactobacillales was reduced compared to post DSS#2 for all diets. Black bran non-DSS rats had the highest richness and diversity. Colonic injury negatively correlated with the proportion of Firmicutes, Actinobacteria, and Lactobacillales, and positively correlated with Unknown and Unclassified groups. Bran diets reduced the severity of epithelial injury, maintained fecal butyrate, and prevented microbial dysbiosis and depletion during DSS-induced colitis. IRON+RAD decreased SCFA concentrations. Low and high LET radiation, HLU, IRON and spaceflight increased Bacteroidetes and decreased Firmicutes. HLU and spaceflight increased Clostridiales and decreased Lactobacillales. RAD and IRON+RAD animals had increased Lactobacillales and significantly lower Clostridiales compared to CON and IRON. TLR9 and IL-6 were downregulated by RAD. TLR4, TFF3 and TGF? differentially changed with IRON and spaceflight. Microgravity independently affected the microbiota, regardless of radiation energy or dose. Each environmental insult differentially altered the microbiota and mucosal gene expression, with distinct diet, microgravity, and radiation effects observed. Bran diets mitigated deleterious effects of colitis, maintained barrier integrity, and prevented microbiota dysbiosis.Item Estrogenic Properties of Sorghum Phenolics: Possible Role in Colon Cancer Prevention(2013-07-03) Yang, LiyiConsumption of whole grains has been linked to reduced risk of colon cancer. This study determined estrogenic activity of sorghum phenolic extracts of different phenolic profiles and identified possible estrogenic compounds in sorghum in vitro, as well as evaluated the potential of estrogenic sorghum phenolic extracts to prevent colon carcinogenesis in vivo. The thermal stability of sorghum 3-deoxyanthocyanins was also studied, to determine their suitability as functional food colorants. White and TX430 (black) sorghum extracts showed estrogenic activity in cell models predominantly expressing estrogen receptor-? (ER?) or ER? at 5 and 10 ?g/mL, respectively. The same treatments led to induction of apoptosis in cells expressing ER?. The red TX2911 sorghum did not possess these activities. Compositional analysis revealed differences in flavones and flavanones. Flavones with estrogen-like properties, i.e. luteolin and apigenin, were detected in White and TX430 (black) sorghum extracts, but not in red TX2911 extract. Naringenin, a flavanone known to antagonize ER? signalling, was only detected in the red TX2911 extract. Additional experiments with sorghum extracts of distinct flavones/flavanone ratio, as well as with pure apigenin and naringenin, suggested that flavones are the more potent ER? agonists in sorghum. On the other hand, 3-deoxyanthocyanins were probably not estrogenic. Estrogenic white and black sorghum phenolic extracts (fed at 1% level in the diet) reduced the number of azoxymethane induced colon premalignant lesion (aberrant crypt foci) by 39.3% and 14.7%, respectively, in ovariectomized mice. Further studies are needed to elucidate the protective mechanisms induced by these sorghum extracts. Sorghum 3-deoxyanthocyanins retained good color stability after 30 minutes of heat treatment at 121 ?C under pressure: More than 80% of color retained in pH 1 and 2 HCl and citric acid solutions, and 39-84% retained from pHs 3-7. Formic acid negatively affected the color stability at pH 1 and pH 2 due to its reducing capacity. Methoxylation decreased the thermal stability of 3-deoxyanthocyanins. The heat stability of 3-deoxyanthocyanins indicates good potential for food use. Overall, the inherent estrogenic activity of specific sorghum phenolic extracts is a likely mechanism for colon cancer prevention. Further studies are needed to assess physiologically relevant dietary level of sorghum phenolics for prevention of colon cancer, and effect of food processing on the activity and bioavailability of the chemopreventive components.