Identification of a dehydrodimer of avenanthramide phytoalexin in oats

A new compound (1) was found to accumulate when oat leaves were treated with elicitors. A reaction with peroxidase and avenanthramide B, an oat phytoalexin, in the presence of hydrogen peroxide resulted in the formation of 1. The chemical structure of 1 was determined to be a cyclic dehydrodimer of avenanthramide B based on spectroscopic analyses and chemical derivatization, and 1 was named bisavenanthramide B.