Yerba mate tea and mate saponins prevented azoxymethane‐induced inflammation of rat colon through suppression of NF‐κB p65ser 311 signaling via IκB‐α and GSK‐3β reduced phosphorylation

Yerba mate tea (YMT) has a chemopreventive role in a variety of inflammatory diseases. The objective was to determine the capability of YMT and mate saponins to prevent azoxymethane (AOM)‐induced colonic inflammation in rats. YMT (2% dry leaves, w/v, as a source of drinking fluid) ( n = 15) and mate saponins (0.01% in the diet, at a concentration present in one cup of YMT) ( n = 15) were given ad libitum to rats 2 weeks prior to AOM‐injection until the end of the study; while control rats ( n = 15) received a basal diet and drinking water. After 8‐weeks of study, total colonic mucosa was scraped ( n = 3 rats/group) and the remaining colons ( n =12 rats/group) were cut into three equal sections and aberrant crypt foci (ACF) were analyzed. YMT reduced ACF formation from 113 (control group) to 89 ( P < 0.05). YMT and mate saponins reduced the expression of proinflammatory molecules COX‐2 and iNOS with concomitant reduction in p‐p65 ( P < 0.05). Immunohistochemical analysis of the formalin‐fixed middle colons showed that YMT and mate saponins reduced the expression of p‐p65 ser311 by 45.7% and 43.1%, respectively, in comparison to the control ( P < 0.05). In addition, the expression of molecules upstream of NF‐κB such as p‐IκB‐α and p‐GSK‐3β Y216 was downregulated by YMT 24.7% and 24.4%, respectively ( P < 0.05). Results suggest the mechanism involved in the chemopreventive effect of YMT and mate saponin consumption in AOM induced‐colonic inflammation in rats is through inhibition of NF‐κB. © 2013 BioFactors, 39(4):430–440, 2013