Distribution of lignans in Panicum miliaceum, Fagopyrum esculentum, Fagopyrum tataricum, and Amaranthus hypochondriacus

•The level of lignans differed between plant parts of all species.•The highest total content of lignans was in the roots of tartary buckwheat.•The dominant lignan of tartary buckwheat was (-)-7-hydroxymatairesinol.•Varietal differences in lignan levels were significant in millet and common buckwheat.