Fermented wheat aleurone inhibits growth and induces apoptosis in human HT29 colon adenocarcinoma cells

Abstract

Fermentation of dietary fibre by the gut microflora may enhance levels of SCFA, which are potentially chemoprotective against colon cancer. Functional food containing wheat aleurone may prevent cancer by influencing cell cycle and cell death. We investigated effects of fermented wheat aleurone on growth and apoptosis of HT29 cells. Wheat aleurone, flour and bran were digested and fermented in vitro. The resulting fermentation supernatants (fs) were analysed for their major metabolites (SCFA, bile acids and ammonia). HT29 cells were treated for 24-72 h with the fs or synthetic mixtures mimicking the fs in SCFA, butyrate or deoxycholic acid (DCA) contents, and the influence on cell growth was determined. Fs aleurone was used to investigate the modulation of apoptosis and cell cycle. The fermented wheat samples contained two-to threefold higher amounts of SCFA than the faeces control (blank), but reduced levels of bile acids and increased concentrations of ammonia. Fs aleurone and flour equally reduced cell growth of HT29 more effectively than the corresponding blank and the SCFA mixtures. The EC 50 (48 h) ranged from 10 % (flour) to 19 % (blank). Markedly after 48 h, fs aleurone (10 %) significantly induced apoptosis and inhibited cell proliferation by arresting the cell cycle in the G0/G1 phase. In conclusion, fermentation of wheat aleurone results in a reduced level of tumour-promoting DCA, but higher levels of potentially chemopreventive SCFA. Fermented wheat aleurone is able to induce apoptosis and to block cell cycle -two essential markers of secondary chemoprevention.

In vitro fermentation of nuts results in the formation of butyrate and c9,t11 conjugated linoleic acid as chemopreventive metabolites

“…The fermentation process led to a significant increase in SCFA with a shift of molar ratios toward butyrate as well as a reduction in the pH value in the FS of in vitro fermented nut samples. These results are in line with former studies which have shown that the fermentation of dietary fiber or fiber-rich foods results in the formation of SCFA and concurrently in lower pH values [31,32]. Similar results have also been obtained by Lux et al [22], who applied different types of nuts to an in vitro simulated digestion.…”

“…In addition, the SCFA-mediated lowering of pH values in the FS might lead to reduced solubility of secondary BA as well as a reduction in 7α-dehydroxylase activity, which catalyzes the conversion of primary into secondary BA [50]. The results of the present study are in line with former studies, which have also shown a reduction in secondary BA concentrations upon in vitro fermentation of different dietary fiber sources [22,24,31,32].…”

Influence of roasting on the chemopreventive potential of macadamia nuts

“…These results are in line with former studies which revealed induction of apoptosis in LT97 cells by FS obtained from different raw nut varieties including macadamia nuts [18], or other dietary fiber sources producing butyrate as fermentation end product [29,30,38]. Again, no direct impact of different roasting conditions on apoptotic potential of fermented macadamia nuts could be observed in the present study.…”

“…These results are in line with other studies demonstrating growth inhibition of LT97 colon adenoma [18] or HT29 colon carcinoma cells [28] by FS obtained from different raw nut varieties including macadamia. Growth inhibition of colon adenoma or cancer cells could also be shown for FS obtained from other dietary fiber rich sources such as bread [29] or wheat aleurone [30], respectively. In the present study, the roasting process had no distinct effect on the growth inhibitory potential of macadamia nuts, indicating that growth inhibition is caused by substances resulting from fermentation of macadamia nut samples such as butyrate which is unaffected by an upstream heat treatment of the nuts.…”

Comparative study of colorectal health related compounds in different types of bread: Analysis of bread samples pre and post digestion in a batch fermentation model of the human intestine

“…Bread samples and control samples (reagent blank as well as inulin (Synergy1 Ò ; Beneo-Orafti, Mannheim, Germany)) were subjected to an in vitro digestion after Aura, Härkönen, Fabritius, and Poutanen (1999) and Barry et al (1995) as described by Borowicki et al (2010).…”