Thermal Processing has no Impact on Chemopreventive Effects of Oat and Barley Kernels in LT97 Colon Adenoma Cells

Abstract

The unique dietary fiber composition with high contents of β-glucan contributes to the health-promoting properties of oat and barley and may mediate a reduction of colon cancer risk. In the present study, chemopreventive effects of oat and barley (beta^®barley) kernels were investigated. In order to address the impact of thermal processing on these effects, kernels were roasted (150–180 °C, approx. 20 min), digested and fermented using an In Vitro human digestion model. Concentrations of short-chain fatty acids (SCFA) and ammonia were determined in fermentation supernatants (FS). Growth inhibition, apoptosis, DNA integrity and gene expression of catalase were analyzed in LT97 colon adenoma cells. Concentrations of SCFA, particularly butyrate, were higher in oat/barley FS (2.2-fold, on average), while ammonia levels were significantly lower (0.7-fold, on average) than in the fermentation control. Treatment of LT97 cells with FS of oat/barley kernels led to a significant time- and dose-dependent growth reduction, a significant increase in caspase-3 activity and enhanced levels of catalase mRNA, without exhibiting genotoxic effects. In general, the results indicate a chemopreventive potential of In Vitro fermented oat and waxy winter barley mediated mainly by growth inhibitory and apoptotic effects, which are preserved after thermal processing.

Acknowledgements

This IGF project (AiF 19351 BR) of the FEI (Research Association of the German Food Industry) was supported via AiF (German Federation of Industrial Research Associations) within the program for promoting the Industrial Collective Research (IGF) of the German Ministry of Economic Affairs and Energy (BMWi), based on a resolution of the German Parliament. We would like to thank Dieckmann Cereals (Rinteln, Germany) for allocation of raw barley products and we thank Peter Kölln GmbH & Co. KGaA for allocation of raw oat products. We also thank Probat-Werke von Gimborn Maschinenfabrik GmbH (Emmerich am Rhein, Germany) for roasting the barley products, especially Thomas Koziorowski and Thomas Elshoff. Furthermore, we would like to express our gratitude to Sandra Hebestreit from the Department of Nutritional Toxicology for her excellent technical assistance. We also thank Silvana Zetzmann, Milena Franziska Mayr and Esther Woschee from the Department of Nutritional Toxicology for performing catalase activity measurements. Finally, we thank Carsten Rohrer from the Department of Nutritional Biochemistry and Physiology for performing SCFA analysis.

Author Contributions

W.S., C.D., S.L., and M.G. designed the study. J.A. and W.S. were responsible for experimental work. W.S. and J.A. performed data evaluation and statistical analyses. W.S. and M.G. wrote the manuscript. C.D., S.L., and M.G. reviewed the manuscript. W.S. and M.G. had primary responsibility for final content. All authors read and approved the manuscript.

Disclosure Statement

No potential conflict of interest was reported by authors.