| Abstract
| - Avenanthramide B is an oat phytoalexin produced in response to pathogen attack and elicitation. Wefound the formation of new dimers (1−5) of avenanthramide B in elicited oat leaves. The dimers weresynthesized by a reaction of peroxidase and avenanthramide B in the presence of hydrogen peroxide.The structures of 1−5 were determined by spectroscopic analyses, chemical derivatization, and 15N labeling.Compound 1 was a dehydrodimer of avenanthramide B with a bisbutane lactam skeleton, while 2−4were monohydrated dehydrodimers with butane lactam structures. Compound 5 was also a monohydrateddehydrodimer but with a tetrahydrofuran structure. All the compounds were classified into lignanamidesthat were formed by an 8‘-8‘ coupling reaction between two avenanthramide B units.
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