Efeito preventivo da yacon (Smallanthus sonchifolius) nas alterações inflamatórias, oxidativas e da integridade intestinal em modelo animal de carcinogênese colorretal

Abstract

Colorectal cancer (CRC) presents dietary factors related to its carcinogenic process. Yacon (Smallanthus sonchifolius) is a functional food with prebiotic activity as source of fructooligosaccharides (FOS), which are fermented by bifidobacteria with positive effects to the intestinal health. The present study investigated the prebiotic effect of yacon flour (YF), source of FOS, on intestinal barrier integrity, inflammatory response and oxidative stress in animal model of induced colorectal cancer. Wistar rats were distributed in 4 groups: S (without CRC and YF, n=10), C (with CRC and without YF, n=12), Y (without CRC and with YF, n=10), CY (with CRC and YF, n=12). Animals of groups S and C received AIN-93 M diet and animals of groups Y and CY received the same diet but added with YF in amounts to provide 5 % FOS, during the 16 weeks of experiment. From week 4 to 8, the animals of C and CY groups received, by subcutaneous via, 25 mg/ kg body weight of 1.2-dimethilydrazine (DMH) once a week. In the last week, 24 h-urine collection was performed for intestinal permeability analysis using lactulose and mannitol. Blood sample was collected to the analysis of interleukin (IL)-10 and IL-12, tumor necrosis factor- alpha (TNF-a) and total antioxidant capacity (TAC). Large intestine was collected for intraluminal pH, short chain fatty acids (SCFA) and secretory immunoglobulin A (sIgA) analysis. Normal distributed data were analyzed by Two-way ANOVA (analysis of variance) followed by Newmans-Keuls test (p<0.05), using GraphPad Prism®, version 7. The animals induced to cancer had higher TNF- a, SCFA (acetate, propionate and butyrate), and lower TAC. The yacon flour reduced the intraluminal pH and lactulose/mannitol ratio, but had no effect on IL-10, IL-12 and TNF- a levels. Also, the levels of sIgA were increased only in the group fed YF without CRC (group Y). It was observed an increase of mannitol and CAT in group CY, showing a significant interaction of YF x CRC. Therefore, yacon flour consumption promoted beneficial effects on the intestinal health of colorectal cancer animals. As a source of FOS, yacon showed to improve the intestinal barrier and mucosal immunity particularly in healthy animals.