Cyclic Peptides from Higher Plants. 34. Segetalins G and H, Structures and Estrogen-like Activity of Cyclic Pentapeptides from Vaccaria segetalis

Segetalins G and H (1−2) possessing estrogen-like activity are cyclic pentapeptides from the seeds of Vaccaria segetalis. Their structures, cyclo(-Gly-Ala-Lys-Tyr-Val) (1) and cyclo(-Gly-Phe-Ser-Tyr-Arg-) (2), were determined by interpretation of spectral data.