Article

Protective effects of yacon (Smallanthus sonchifolius) intake on experimental colon carcinogenesis

UNESP Sao Paulo State University, Institute of Biosciences, Program of Post-Graduation in General and Applied Biology Program, Botucatu 18618-970, SP, Brazil.
Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association (Impact Factor: 2.61). 05/2012; 50(8):2902-10. DOI: 10.1016/j.fct.2012.05.006
Source: PubMed

ABSTRACT Yacon (Smallanthus sonchifolius), a tuberous root native to the Andean region of South America, contains high concentration of fructans with potential for colon cancer prevention. This study investigated the potential beneficial of yacon intake on colon carcinogenesis induced by 1,2-dimethylhydrazine (DMH) in male Wistar rats. After 4 weeks of DMH-initiation, groups were fed basal diet (G1 and G6) or basal diet containing dried extract of yacon root at 0.5% (G2), 1.0% (G3 and G5) or a synbiotic formulation (G4) (1.0% yacon plus Lactobacillus casei at 2.5 × 10(10)CFU per g diet) for 13 weeks. At week 20, a significant reduction in number and multiplicity of aberrant crypt foci (ACF) and in number of invasive adenocarcinomas was observed in the groups orally treated with 1.0% yacon (G3) or the synbiotic formulation (G4) (0.05<p<0.001). Tumor multiplicity (noninvasive plus invasive) was significantly lower in the group fed synbiotic formulation (p<0.02). A significant reduction in cell proliferation in colonic crypts and tumors and short chain fatty acids (SCFA) caecal contents was observed in the groups orally treated with 1.0% yacon (G3) or the synbiotic formulation (G4). Therefore, the findings this study indicate that yacon and yacon plus L. casei intake may reduce the development of chemically-induced colon cancer.

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    • "Studies have reported that yacon also presents antioxidant activity related to compounds such as flavonoids (Arnao et al. 2011), phenolic acids (Castro et al. 2012), and tryptophan (Yan et al. 1999), beyond anti-inflammatory (Honoré et al. 2012), anti-obesity (Hasani-Ranjbar et al. 2013), antibacterial (Joung et al. 2010), antifungal (Yun et al. 2012), and anticancer (Moura et al. 2012) activities. Yacon has a high moisture content (around 83–90 % of the fresh weight) and a structure composed by weak internal tissues, which increase the incidence of deterioration during harvesting, packaging, and transportation. "
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    • "In the initial phase of tumor progression, groups that ingested AYE (G4) and its association with L. acidophilus CRL 1014 (G5) showed better suppressor response when compared to DMH group (G2) and probiotic (G3), once only 50 and 66.67% of macroscopic tumors in G4 (prebiotic) and G5 (synbiotic) were adenocarcinomas (Fig. 3A). Likewise, de Moura et al. (2012) reported lower proportion of adenocarcinomas induced by DMH in groups receiving a synbiotic formulation (1% yacon root and L. casei at 2.5 × 10 −10 CFU per gram). However, no additional or synergic effects were observed using our synbiotic formulation. "
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    • "The protein expression levels of Ki-67 (i.e., cell proliferation marker), cleaved caspase-3 (i.e., apoptosis marker) and b-catenin and connexin 43 (Cx43) (i.e., tumor progression markers) in the colon tumors were detected immunohistochemically using a polymer system (MACH 4 Universal HRP polymer Detection, Biocare, CA, USA). Briefly, deparaffinated 5 lm colon tumor sections on silanised slides were treated sequentially with 0.01 M citrate buffer (pH 6.0) at 120 °C for 5 min in a Pascal Pressure Chamber (Dako Cytomation Denmark A/S), 3% H 2 O 2 in PBS for 10 min, nonfat milk for 60 min, either mouse anti-Ki-67 (1:100 dilution, Abcam ab16667, Cambridge, MA 02139), rabbit polyclonal cleaved anti-caspase-3 (clone Asp 175, 1:100 dilution, Cell Signalizing Technology, Inc., Danvers, MA, USA), rabbit polyclonal anti-b-catenin (clone ab6302, Abcam, MA, USA) or rabbit polyclonal anti- Cx43 (clone GJA1, Abcam, MA, USA) antibodies overnight at 4 °C, the mouse probe for 30 min at room temperature and the HRP polymer for another 30 min at room temperature (Moura et al., 2012). Chromogenic development was accomplished with 3,3 0 -diaminobenzidine tetrahydrochroride (Sigma–Aldrich, Co, USA). "
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