LAUSR

Avenanthramides (AVNs) were a unique kind of polyphenols which were only detected in the oats and have been demonstrated to exhibit strong antioxidant activities but low bioavailability. The purpose of the present research was to evaluate the absorption rates and mechanism of AVNs (AVN 2c, AVN 2f, and AVN 2p) using Caco-2 cell model and clarify the influence of absorption process on the antioxidant capacities of AVNs. Furthermore, ferulic acid and caffeic acid were used to compare with AVNs on their absorption rates and antioxidant activities. Results showed that the apparent absorption rates (Papp) of AVN 2c, AVN 2f, and AVN 2p were 0.65 ± 0.05 × 10-6 cm/s, 1.18 ± 0.16 × 10-6 cm/s, and 1.44 ± 0.09 × 10-6 cm/s, respectively, which were significantly lower than that of caffeic acid (3.76 ± 0.31 × 10-6 cm/s) and ferulic acid (1.69 ± 0.13×10-5 cm/s). Moreover, the metabolites (caffeic acid, ferulic acid, and AVN 2f) of AVNs after absorption were detected and quantified by high performance liquid chromatography-mass spectrometry. Before absorption, although the antioxidant capacity of AVNs was significantly stronger than that of ferulic acid and caffeic acid, there was an opposite result after absorption. In addition, AVNs transported the Caco-2 monolayer by paracellular diffusion, and affected by monoamine oxidase and efflux transporters (P-gp, MRP2) during absorption. Co-administration of quercetin could significantly improve the absorption rates of AVNs.