Examination of the Bioavailability and Bioconversion of Wheat Bran-Bound Ferulic Acid: Insights into Gastrointestinal Processing and Colonic Metabolites

The postingestion journey and bioconversion of wheat bran-bound ferulic acid, a known beneficial phytochemical, remain insufficiently understood. This study aims to systematically investigate its bioaccessibility, bioavailability, excretion, and colonic metabolism, both in vitro and in vivo. Initial analysis confirmed the abundance and bioactivity of ferulic acid in wheat bran. Using a simulated gastrointestinal model, 1.7% of the ferulic acid was found to be bioaccessible, in contrast to 43.4% for total phenolics. In vivo bioavailability was assessed in rats via oral gavage of cooked wheat bran, with a plasma ferulic acid level peaking at 32.5 ± 4.9 ng/mL, corresponding to an absorption rate of 0.3%, while 1% was excreted in urine. Fecal metabolomic analysis revealed extensive colonic bioconversion, with elevated levels of ferulic acid and its metabolites, including 3-phenylpropionic acid, dihydroferulic acid, 5-hydroxyferulic acid, and hippuric acid. Novel metabolites, such as 3-(2,5-dimethoxyphenyl)propionic acid and N-(2-furoyl)glycine, were detected for the first time. These findings shed light on the complex biotransformation of wheat bran-bound ferulic acid and its potential health implications.