Structure of a new cyclic nonapeptide, segetalin F, and vasorelaxant activity of segetalins from Vaccaria segetalis.

A new cyclic nonapeptide, segetalin F, has been isolated from the seeds of Vaccaria segetalis and the structure including absolute stereochemistry was elucidated by using 2D NMR and chemical means. A series of segetalins showed a vasorelaxant activity against norepinephrine (NE)-induced contractions of rat aorta.