Inhibitory Effects of a Soluble Dietary Fiber from Amorphophallus konjac on Cytotoxicity and DNA Damage Induced by Fecal Water in Caco-2 Cells

Abstract

The aims of this study were to determine the effects of konjac glucomannan (KGM), a water-soluble dietary fiber from Amorphophallu konjac C. Koch, on the cytotoxicity and DNA damage of fecal water-treated Caco-2 cells, a human colon adenocarcinoma cell line, and to compare these effects with those of inulin, oligofructose (FO), cellulose and no fiber diet. In addition, the possible mechanisms by which dietary fibers modulated the toxicity of feces were investigated. Seven-week-old BALB/c mice were randomly allocated to consume an AIN-93 diet that contained no dietary fiber (FF) or 5 % (w/w) KGM, inulin, FO, or cellulose for 3 weeks. Fresh feces were collected during days 18 - 21. Our results indicated that the survival rate (%) of fecal water-treated Caco-2 cells was similarly enhanced by each dietary fiber as compared with that of FF group, respectively. The inhibition of fecal water-induced DNA damage of Caco-2 cells was in the descending order of inulin> FO> cellulose, KGM group. Cellulose significantly exerted a bulk effect, while KGM, inulin and FO significantly increased the ratio of lactobacilli and bifidobacteria in feces, respectively, as well as the ferrous ion-chelating ability of fecal water, respectively. Therefore, this study suggests that KGM, inulin and FO may reduce the toxicity of fecal water mainly by increasing the fecal probiotics and ferrous ion-chelating activities while cellulose may act mainly by increasing the fecal bulk.

Abbreviations

FF: fiber free

FO: oligofructose

KGM: konjac glucomannan

Key words

Dietary fiber - Amorphophallus konjac C. Koch - Araceae - konjac glucomannan - fructan oligosaccharides - cellulose - fecal water

References

• 1 Tye R. Konjac flour: properties and application.  Food Technol. 1991;  45 11-61.
• 2 Katsuraya K, Okuyama K, Hatanaka K, Oshima R, Sato T, Matsuzaki K. Constitution of konjac glucomannan: chemical analysis and ¹³C NMR spectroscopy.  Carbohydr Polymer. 2003;  53 183-9.
• 3 Ratcliffe I, Williams P A, Viebke C, Meadows J. Physicochemical characterization of konjac glucomannan.  . 2005;  6 1977-86.
• 4 Marzio L, el Bianco R, Donne M D, Pieramico O, Cuccurullo F. Mouth-to-cecum transit time in patients affected by chronic constipation: effect of glucomannan.  Am J Gastroenterol. 1989;  84 888-91.
• 5 Loening-Baucke V, Miele E, Staiano A. Fiber (glucomannan) is beneficial in the treatment of childhood constipation.  Pediatrics. 2004;  113 259-64.
• 6 Chen H L, Fan Y H, Chen M E, Chan Y. Unhydrolyzed and hydrolyzed konjac glucomannans modulated cecal and fecal microflora in Balb/c mice.  Nutrition. 2005;  21 1059-64.
• 7 Chen H L, Sheu W H, Tai T S, Liaw Y P, Chen Y C. Konjac supplement alleviated hypercholesterolemia and hyperglycemia in type 2 diabetic subjects-a randomized double-blind trial.  . 2003;  22 36-42.
• 8 Burkitt D P. Related disease - related cause.  Lancet. 1969;  6 1229-31.
• 9 Levi F, Pasche C, La Vecchia C, Lucchini F, Franceschi S. Food groups and colorectal cancer risk.  . 1999;  79 1283-7.
• 10 Pool-Zobel B L, Neudecker C, Domizlaff I, Ji S, Schillinger U, Rumney C. et al . Lactobacillus- and bifidobacterium-mediated antigenotoxicity in the colon of rats.  Nutr Cancer. 1996;  26 365-80.
• 11 Balansky R, Gyosheva B, Ganchev G, Mircheva Z, Minkova S, Georgiev G. Inhibitory effects of freeze-dried milk fermented by selected Lactobacillus bulgaricus strains on carcinogenesis induced by1,2-dimethylhydrazine in rats and by diethylnitrosamine in hamsters.  Cancer Lett.. 1999;  147 125-37.
• 12 Burns A J, Rowland I R. Antigenotoxicity of probiotics and prebiotics on faecal water-induced DNA damage in human colon adenocarcinoma cells.  Mutat Res. 2004;  551 233-43.
• 13 Rieger M A, Parlesak A, Pool-Zobel B L, Rechkemmer G, Bode C A. Diet high in fat and meat but low in dietary fiber increases the genotoxic potential of ”faecal water”.  Carcinogenesis. 1999;  20 2311-6.
• 14 National Institutes of Health. Guide for the care and use of laboratory animals. National Research Council 1985: 85-123.
• 15 Dubois M, Gilles K A, Hamilton J K, Robers P A, Smith F. Colorimetric method for determination of sugars and related substances.  Anal Chem. 1956;  28 350-6.
• 16 Aued S, Carvalho J B, Tavares M, Zanelatto A M, Bacetti L B. Starch determination in sausages (hot dogs): comparison between the Fehling and Somogyi-Nelson methods and evaluation of methodology for starch extraction.  Revista-do-Instituto-Adolfo-Lutz. 1990;  50 251-6.
• 17 Phillis H J. Dye exclusion tests for cell viability. In: Kruse PF, Patterswon MK, editors Tissue culture method and application. New York; Academic Press 1973.
• 18 Pool-Zobel B L, Bub A, Muller H, Wollowski I, Rechkemmer G. Consumption of vegetables reduces genetic damage in humans: first results of a human intervention trial with carotenoid-rich foods.  Carcinogenesis. 1997;  18 1847-50.
• 19 Collins A R, Ma A G, Duthie S J. The kinetics of repair of oxidative DNA damage (strand breaks and oxidized pyrimidines) in human cells.  Mutat Res. 1995;  336 69-77.
• 20 Pankuch G A, Appelbaum P C. Agar medium for gas-liquid chromatography of anaerobes.  Am J Clin Pathol. 1986;  85 82-6.
• 21 Munoa F J, Pares R. Selective medium for isolation and enumeration of Bifidobacterium spp.  Appl Environ Microbiol. 1988;  54 1715-8.
• 22 Gibb B, Freame B. Methods for the recovery of clostridia from foods.  J Appl Bacteriol. 1965;  28 95-111.
• 23 Wang R F, Cao W W, Cerniglia C. PCR detection and quantitation of predominant anaerobic bacteria in human and animal fecal samples.  Appl Environ Microbiol. 1996;  62 1242-47.
• 24 Dinis T C, Maderia V M, Almeida L M. Action of phenolic derivatives (acetaminophen, salicylate, and 5-aminosalicylate) as inhibitors of membrane lipid peroxidation and as peroxyl radical scavengers.  Arch Biochem Biophys.. 1994;  315 161-9.
• 25 Sambuy Y, De Angelis I, Ranaldi G, Scarino M L, Stammati A, Zucco F. The Caco-2 cell line as a model of the intestinal barrier: influence of cell and culture-related factors on Caco-2 cell functional characteristics.  . 2005;  21 1-26.
• 26 Pool-Zobel B L. Inulin-type fructans and reduction in colon cancer risk: review of experimental and human data.  Br J Nutr. 2005;  I 1 S73-90.
• 27 Roberfroid M B, Van Loo J A, Gibson G R. The bifidogenic nature of chicory inulin and its hydrolysis products.  . 1998;  128 11-9.
• 28 van de Wiele T, Boon N, Possemiers S, Jacobs H, Verstraete W. Inulin-type fructans of longer degree of polymerization exert more pronounced in vitro prebiotic effects.  . 2007;  102 452-60.
• 29 Erhardt J G, Lim S S, Bode J C, Bode C. A diet rich in fat and poor in dietary fiber increases the in vitro formation of reactive oxygen species in human feces.  . 1997;  127 706-9.
• 30 Nakaji S, Ishiguro S, Iwane S, Ohta M, Sugawara K, Sakamoto J. et al . The prevention of colon carcinogenesis in rats by dietary cellulose is greater than the promotive effect of dietary lard as assessed by repeated endoscopic observation.  . 2004;  134 35-9.