Trapping of reactive carbonyl species by fiber-bound polyphenols from whole grains under simulated physiological conditions

The carbonyl trapping activity of bound-polyphenol rich insoluble dietary fiber (BP-IDF) from different whole grains and underlying mechanism of these BP-IDF actions were studied under simulated physiological conditions. We found that the black highland barley BP-IDF exhibited the most pronounced effect in scavenging carbonyls by trapping 88.7%, 72.2%, 95.7%, and 31.4% for methylglyoxal, glyoxal, acrolein, and malondialdehyde within 24 h, respectively. After vitro gastrointestinal digestion, the black highland barley BP-IDF still retained considerable trapping activity for carbonyls. The carbonyl scavenging capacity was reduced by up to 93% after removing bound polyphenols from the black highland barley BP-IDF, which was consistent with the reduction in its total phenolic content. Moreover, the formation of adducts between reactive carbonyl species (RCS) and polyphenols bound to insoluble dietary fiber (IDF) was also detected. Overall, these findings confirmed that IDF-bound polyphenols were still active to trap RCS, indicating the potential benefits of BP-IDF from whole grains as functional ingredients to limit carbonyl stress across the gastrointestinal tract.