Avenanthramide Aglycones and Glucosides in Oat Bran: Chemical Profile, Levels in Commercial Oat Products, and Cytotoxicity to Human Colon Cancer Cells

Avenanthramides (AVAs), unique phytochemicals in oat, have attracted an increasing amount of attention due to their outstanding health benefits. However, the chemical profile and the levels of AVAs in commercial oat products as well as their health benefits have not been examined in detail. In the present study, a total of 29 AVA aglycones and AVA glucosides were identified and characterized from oat bran using NMR (1D and 2D NMR) and LC-MS techniques. Among them, 17 novel AVA glucosides were reported in oat bran for the first time. The most abundant AVA glucoside, 2c-3′-O-glc, had a similar growth inhibitory activity with the major AVA, 2c, against HCT-116 and HT-29 human colon cancer cells, indicating glucosylation does not affect the growth inhibitory effects of AVAs. Furthermore, the levels of all individual AVAs in 13 commercial oat products were analyzed using HPLC-MS/MS. The total AVAs contents in various oat products ranged from 9.22 to 61.77 mg/kg (fresh weight).