Translating In Vitro Acrolein-Trapping Capacities of Tea Polyphenol and Soy Genistein to In Vivo Situation is Mediated by the Bioavailability and Biotransformation of Individual Polyphenols.

SCOPE: Acrolein is a highly toxic unsaturated aldehyde. Humans are both endogenously and exogenously exposed to acrolein. Long-term exposure to acrolein leads to various chronic diseases. Dietary polyphenols have been reported to be able to attenuate acrolein-induced toxicity in vitro via formation of acrolein-polyphenol conjugates. However, whether in vitro acrolein-trapping abilities of polyphenols can be maintained under in vivo environments is still unknown.

METHODS AND RESULTS: Two most commonly consumed dietary polyphenols, (-)-epigallocatechin-3-gallate (EGCG) from tea and genistein from soy, were used to evaluate for their anti-acrolein behaviors both in vitro and in mice. Tea EGCG exerted much higher capacity to capture acrolein than soy genistein in vitro. But translation of in vitro anti-acrolein activity into in vivo was mainly mediated by bioavailability and biotransformation of individual polyphenols. We found that 1) both absorbed EGCG and genistein could trap endogenous ACR by forming mono-ACR adducts and eventually be excreted into mouse urine; 2) both absorbed EGCG and genistein could produce active metabolites, MeEGCG and orobol, to scavenge endogenous ACR; 3) both MeEGCG and non-absorbed EGCG showed ability to trap ACR in the gut; 4) considerable amounts of microbial metabolites of genistein displayed enhanced anti-ACR capacity both in the body and in the gut, compared to genistein; and 5) biotransformation of genistein is able to boost its in vivo anti-ACR capacity, compared to EGCG.

CONCLUSION: Our findings demonstrate that in vivo anti-acrolein ability of dietary polyphenols cannot be reflected solely based on their in vitro ability. The bioavailability and biotransformation of individual polyphenols especially gut microbiome contribute to in vivo anti-acrolein ability of dietary polyphenols. This article is protected by copyright. All rights reserved.