RESUMO
High red meat intake is associated with the risk of colorectal cancer (CRC), whereas dietary fibers, such as resistant starch (RS) seemed to protect against CRC. The aim of this study was to determine whether high-amylose potato starch (HAPS), high-amylose maize starch (HAMS), and butyrylated high-amylose maize starch (HAMSB)-produced by an organocatalytic route-could oppose the negative effects of a high-protein meat diet (HPM), in terms of fermentation pattern, cecal microbial composition, and colonic biomarkers of CRC. Rats were fed a HPM diet or an HPM diet where 10% of the maize starch was substituted with either HAPS, HAMS, or HAMSB, for 4 weeks. Feces, cecum digesta, and colonic tissue were obtained for biochemical, microbial, gene expression (oncogenic microRNA), and immuno-histochemical (O6-methyl-2-deoxyguanosine (O6MeG) adduct) analysis. The HAMS and HAMSB diets shifted the fecal fermentation pattern from protein towards carbohydrate metabolism. The HAMSB diet also substantially increased fecal butyrate concentration and the pool, compared with the other diets. All three RS treatments altered the cecal microbial composition in a diet specific manner. HAPS and HAMSB showed CRC preventive effects, based on the reduced colonic oncogenic miR17-92 cluster miRNA expression, but there was no significant diet-induced differences in the colonic O6MeG adduct levels. Overall, HAMSB consumption showed the most potential for limiting the negative effects of a high-meat diet.
Assuntos
Amilose/metabolismo , Neoplasias Colorretais/dietoterapia , Dieta Rica em Proteínas/efeitos adversos , Carboidratos da Dieta/metabolismo , Fermentação , Microbioma Gastrointestinal , Intestino Grosso/metabolismo , Amilose/química , Amilose/farmacologia , Animais , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Butiratos/química , Neoplasias Colorretais/etiologia , Neoplasias Colorretais/prevenção & controle , Carboidratos da Dieta/farmacologia , Carboidratos da Dieta/uso terapêutico , Intestino Grosso/efeitos dos fármacos , Intestino Grosso/microbiologia , Masculino , MicroRNAs/genética , MicroRNAs/metabolismo , Ratos , Ratos Sprague-Dawley , Solanum tuberosum/química , Zea mays/químicaRESUMO
Components previously reported from Cyclocarya paliurus include the oleananes cyclocaric acids A and B, with cyclocaric acid A possessing an oxetane ring. Isolation of cyclocaric acid A from the plant extract and comparison to the literature report show that the compound originally reported as cyclocaric acid A is, in fact, hederagenin. This was confirmed by independent synthesis of the oxetane and indicates that cyclocaric acid A may not actually be a natural product.