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Query: UMLS:C0699790 (colon cancer)
 28,837 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epidemiological studies have shown that consumption of whole grains and grain-based products is associated with reduced risk of chronic diseases. The health benefits of whole grains are attributed in part to their unique phytochemical composition. However, the phytochemical contents in grains have been commonly underestimated in the literature, because bound phytochemicals were not included. This study was designed to investigate the complete phytochemical profiles in free, soluble conjugated, and insoluble bound forms, as well as their antioxidant activities in uncooked whole grains. Corn had the highest total phenolic content (15.55 +/- 0.60 micromol of gallic acid equiv/g of grain) of the grains tested, followed by wheat (7.99 +/- 0.39 micromol of gallic acid equiv/g of grain), oats (6.53 +/- 0.19 micromol of gallic acid equiv/g of grain), and rice (5.56 +/- 0.17 micromol of gallic acid equiv/g of grain). The major portion of phenolics in grains existed in the bound form (85% in corn, 75% in oats and wheat, and 62% in rice), although free phenolics were frequently reported in the literature. Ferulic acid was the major phenolic compound in grains tested, with free, soluble-conjugated, and bound ferulic acids present in the ratio 0.1:1:100. Corn had the highest total antioxidant activity (181.42 +/- 0.86 micromol of vitamin C equiv/g of grain), followed by wheat (76.70 +/- 1.38 micromol of vitamin C equiv/g of grain), oats (74.67 +/- 1.49 micromol of vitamin C equiv/g of grain), and rice (55.77 +/- 1.62 micromol of vitamin C equiv/g of grain). Bound phytochemicals were the major contributors to the total antioxidant activity: 90% in wheat, 87% in corn, 71% in rice, and 58% in oats. Bound phytochemicals could survive stomach and intestinal digestion to reach the colon. This may partly explain the mechanism of grain consumption in the prevention of colon cancer, other digestive cancers, breast cancer, and prostate cancer, which is supported by epidemiological studies.
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PMID:Antioxidant activity of grains. 1235 99

Activity-guided fractionation of a methanol extract from the fruit of Manilkara zapota cv. Tikal resulted in the isolation of two new antioxidants, methyl 4-O-galloylchlorogenate (1) and 4-O-galloylchlorogenic acid (2), along with eight known polyphenolic antioxidants, namely, methyl chlorogenate (3), dihydromyricetin (4), quercitrin (5), myricitrin (6), (+)-catechin (7), (-)-epicatechin (8), (+)-gallocatechin (9), and gallic acid (10). Of the 10 polyphenols, 1 showed the highest antioxidant activity (IC(50) = 12.9 microM) in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical assay and displayed cytotoxicity in the HCT-116 and SW-480 human colon cancer cell lines with IC(50) values of 190 and 160 microM, respectively. Compound 2 showed high antioxidant activity (IC(50) = 23.5 microM) in the DPPH free-radical assay and displayed cytotoxicity in the HCT-116 and SW-480 human colon cancer cell lines with IC(50) values of 154 and 134 microM, respectively.
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PMID:Bioactive novel polyphenols from the fruit of Manilkara zapota (Sapodilla). 1288 Mar 19

There has been controversy as to whether the antiproliferative activity of dietary phenolic substances on cancer cells is due to the bioactivities of phenolics or the generation of hydrogen peroxide (H2O2) in media as an artifact. This study was to investigate whether the formation of H2O2 by different phenolics induces acute toxicity and carcinogenicity in normal rat liver epithelial cells. Gallic acid, one of the major antioxidants present in fruits and vegetables, dose-dependently generated considerably more H2O2 in DMEM media without cells than did quercetin. Gallic acid exerted stronger antiproliferative activity than quercetin on both Caco-2 human colon cancer cells (Caco-2 cells) and WB-F344 normal rat liver epithelial cells (WB cells) cultured in DMEM media, and the effect was partially reduced by catalase. Furthermore, gallic acid (but not quercetin) also inhibited gap-junction intercellular communication (GJIC; a carcinogenic phenomenon), which was in part protected by the addition of catalase. Exogenous H2O2 addition also inhibited the proliferation of both Caco-2 cells and WB cells and inhibited GJIC in a dose-dependent manner, but these effects were almost abolished by the treatment with catalase. From these results it is concluded that the antiproliferative effects of some antioxidants on cancer cells are partially due to their prooxidant actions.
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PMID:Antiproliferative effects of dietary phenolic substances and hydrogen peroxide. 1576 25

Seed flours from black raspberry, red raspberry, blueberry, cranberry, pinot noir grape, and chardonnay grape were examined for their total fat content, fatty acid composition, total phenolic content (TPC), total anthocyanin content (TAC), radical scavenging capacities against the peroxyl (ORAC) and stable DPPH radicals, chelating capacity against Fe(2+), and antiproliferative activities using the HT-29 colon cancer cell line. Significant levels of fat were detected in the fruit seed flours and their fatty acid profiles may differ from those of the respective seed oils. Cranberry seed flour had the highest level of alpha-linolenic acid (30.9 g/100 g fat) and the lowest ratio of n-6/n-3 fatty acids (1.2/1). The ORAC value of the chardonnay seed flour was 1076.4 Trolox equivalents mumol/g flour, and its TPC was 186.3 mg gallic acid equivalents/g flour. These values were 3-12 times higher than the other tested fruit seed flours. Furthermore, the ORAC value was significantly correlated to the TPC under the experimental conditions (P < 0.05). These fruit seed flours also differed in their TAC values and Fe(2+)-chelating capacities. In addition, black raspberry, cranberry, and chardonnay grape seed flour extracts were evaluated for their antiproliferative effects using HT-29 colon cancer cells. All three tested seed flour extracts significant inhibited HT-29 cell proliferation. The data from this study suggest the potential of developing the value-added use of these fruit seed flours as dietary sources of natural antioxidants and antiproliferative agents for optimal human health.
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PMID:Chemical compositions, antioxidant capacities, and antiproliferative activities of selected fruit seed flours. 1671 95

(-)-Epigallocatechin-3-gallate (EGCG), one of the main constituents of green tea, has been reported to function as an antioxidant with chemopreventive potential. In contrast, we have recently reported that EGCG enhanced pro-matrix metalloproteinase (MMP)-7 in HT-29 human colon cancer cells via spontaneous superoxide generation. In the present study, we examined the effects of dietary antioxidants on both spontaneous and EGCG-upregulated proMMP-7 production in HT-29 cells. Benzyl isothiocyanate (BITC), curcumin (CUR), gallic acid (GA), and N-acetyl-L-cysteine (NAC) reduced that production, while each alone did not have any effect on spontaneous production. None of the dietary factors suppressed EGCG-induced hydrogen peroxide generation in the media tested, whereas BITC, GA, and NAC inhibited the EGCG-enhanced activator protein (AP)-1 transcription activity by 126%, 77%, and 97%, respectively. Although CUR abolished the EGCG-upregulated MMP-7 mRNA expression, it unexpectedly enhanced the AP-1 activity by 502%, suggesting that this factor may disrupt the MMP-7 mRNA stabilization process. Together, our results indicate that dietary antioxidants modulate EGCG-induced MMP-7 production through different mechanisms.
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PMID:Modifying effects of dietary factors on (-)-epigallocatechin-3-gallate-induced pro-matrix metalloproteinase-7 production in HT-29 human colorectal cancer cells. 1792 19

Digalloylresveratrol (DIG) is a new synthetic ester of the naturally occurring polyhydroxyphenolic substances gallic acid and resveratrol which both exert anti-cancer activity in a number of tumor cell lines. The aim of the study was to identify the biochemical effects of DIG in HT-29 human colon cancer cells. DIG induced dose-dependently apoptosis after treatment for 72 h (40 microM DIG caused apoptosis in 45% of cells). DIG led to a substantial imbalance of deoxyribonucleoside triphosphates (dNTPs), the products of the enzyme ribonucleotide reductase (RR) and directly inhibited RR as it significantly reduced the incorporation of (14)C-labeled cytidine into the DNA of tumor cells. Furthermore, DIG affected the cell division and inhibited the transition from S to G2/M phase of the cell cycle. In contrast to resveratrol or gallic acid, DIG did not inhibit cyclooxygenases I and II. When HT-29 cells were simultaneously treated with DIG and 5-FU, the standard chemotherapeutic substance for colon cancer, additive growth inhibitory effects could be observed. With respect to the various biochemical and anti-proliferative effects of DIG in HT-29 cells, we regard DIG as a potential candidate for future treatment options of colon cancer and conclude that further preclinical and in vivo studies are warranted.
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PMID:Digalloylresveratrol, a new phenolic acid derivative induces apoptosis and cell cycle arrest in human HT-29 colon cancer cells. 1895 70

Colon cancer is a major cause of morbidity and mortality in developed and developing countries and its etiology is known to be a combination of hereditary, environmental, dietary factors and lack of physical activity. Chemoprevention offers a novel approach to control the incidence of colon cancer. Gallic acid (GA) is a polyphenol widely present in tea and other plants which is popularly used in the traditional medicine of China. The present study was to evaluate the efficacy of GA supplementation on tissue lipid peroxidation and antioxidant defense system in 1,2-dimethyhydrazine (DMH) induced colon carcinogenesis in male Wistar rats. The rats were assorted into six groups, viz., group1 control rats received modified pellet diet; group 2 rats received GA (50 mg/kg body weight) orally along with modified pellet diet; group 3 rats received DMH (20 mg/kg body weight) subcutaneously once a week for the first 15 weeks; groups 4, 5 and 6 rats received GA along with DMH during the initiation, post- initiation stages and the entire period of study respectively. All the rats were sacrificed at the end of 30 weeks and the tissues were evaluated biochemically. We observed decreased lipid peroxidation (LPO) products such as thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (LOOH) and conjugated dienes (CD) and diminished levels of antioxidants such as superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), glutathione reductase (GR) and glutathione peroxidase (GPx) in the tissues of DMH treated rats, which were elevated significantly on GA supplementation. Moreover, enhanced activity of ascorbic acid and alpha-tocopherol levels were also observed in DMH alone treated rats which were significantly reduced on GA supplementation. Our results suggest that GA could exert a significant chemopreventive effect on DMH induced colon carcinogenesis.
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PMID:Chemopreventive efficacy of gallic acid, an antioxidant and anticarcinogenic polyphenol, against 1,2-dimethyl hydrazine induced rat colon carcinogenesis. 1930 Sep 9

Juices of nine prickly pears (Opuntia spp.) were characterized in terms of color, acidity, sugar content, phenolics, flavonoids, betalains and antioxidant activity and tested in vitro against four cancer cell lines. The juices had pH s, acidities and sugar ranging from 4.27 to 5.46, 0.03 to 0.27% and 8 to 14.7 degrees Brix, respectively. Juices also varied in color from white to purple and contained total phenolics, flavonoids, betaxanthins, betacyanins and antioxidant capacity ranging from 22 to 226 microg gallic acid eq/g, 95 to 374 microg quercetin eq/g, 3 to 189 microg/g, 1.6 to 300 microg/g and 17 to 25 micromoles Trolox eq./mL, respectively. Among the cancer lines tested, viability of prostate and colon cells were the most affected. Moradillo contained the highest flavonoids and diminished both prostate and colon cancer cell viability without affecting mammary or hepatic cancer cells. Rastrero reduced the growth of the four cancer cell lines without affecting normal fibroblast viability. The research shows intervarietal differences among prickly pears in terms of juice properties and phytochemicals that could prevent oxidative stress and cancer.
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PMID:Phenolic composition, antioxidant capacity and in vitro cancer cell cytotoxicity of nine prickly pear (Opuntia spp.) juices. 1946 36

Red meat intake is associated with an increased risk of developing cancer. This is possibly related to the heme content of red meat. Plant derived polyphenols might protect from cancer development via their antioxidant activities. In this study, the impact of an aqueous extract of carob (CE) on hemin-modulated proliferation was investigated. CE, gallic acid (GA) and a known iron chelator (deferoxamine: DFO) significantly reduced the number of human colon cancer HT29 cells. CE and GA were more effective under serum-free conditions than in normal cell culture medium. These effects were abolished by addition of 1 microM hemin at low concentrations of CE and GA. At higher concentrations of CE and GA, both substances reduced cell number despite hemin supplementation. Effects of CE, GA and DFO on cell number could not be linked to iron chelation even though CE and DFO were capable of chelating iron. Furthermore, the effects of high CE concentration point to antioxidative effects other than iron chelation. However, a connection to a reduction of colorectal cancer risk due to consumption of meat with high heme content by CE could not be drawn, since the effective concentrations are beyond the physiologically relevant concentrations.
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PMID:New insight into the influence of carob extract and gallic acid on hemin induced modulation of HT29 cell growth parameters. 1952 81

Recent data suggest that ellagitannins (ETs), a class of hydrolyzable tannins found in some fruits and nuts, may have beneficial effects against colon cancer. In the stomach and gut, ETs hydrolyze to release ellagic acid (EA) and are converted by gut microbiota to urolithin A (UA; 3,8-dihydroxy-6H-dibenzopyran-6-one) type metabolites, which may persist in the colon through enterohepatic circulation. However, little is known about the mechanisms of action of either the native compounds or their metabolites on colon carcinogenesis. Components of Wnt signaling pathways are known to play a pivotal role in human colon carcinogenesis, and inappropriate activation of the signaling cascade is observed in 90% of colorectal cancers. This study investigated the effects of UA, EA, and ET-rich fruit extracts on Wnt signaling in a human 293T cell line using a luciferase reporter of canonical Wnt pathway-mediated transcriptional activation. The ET extracts were obtained from strawberry (Fragaria annassa), Jamun berry (Eugenia jambolana), and pomegranate (Punica granatum) fruit and were all standardized to phenolic content (as gallic acid equivalents, GAEs, by the Folin-Ciocalteu method) and to EA content (by high-performance liquid chromatography methods): strawberry = 20.5% GAE, 5.0% EA; Jamun berry = 20.5% GAE, 4.2% EA; pomegranate = 55% GAE, 3.5% EA. The ET extracts (IC(50) = 28.0-30.0 microg/mL), EA (IC(50) = 19.0 microg/mL; 63 microM), and UA (IC(50) = 9.0 microg/mL; 39 microM) inhibited Wnt signaling, suggesting that ET-rich foods have potential against colon carcinogenesis and that urolithins are relevant bioactive constituents in the colon.
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PMID:Effects of fruit ellagitannin extracts, ellagic acid, and their colonic metabolite, urolithin A, on Wnt signaling. 2001 60


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