Conformational preference for segetalins G and H, cyclic peptides with estrogen-like activity from seeds of Vaccaria segetalis Original Research Article

Three-dimensional structures in DMSO-d6 of segetalins G [cyclo (-Gly-Val-Lys-Tyr-Ala-)] and H [cyclo (-Gly-Tyr-Arg-Phe-Ser-)], cyclic pentapeptides from seeds of Vaccaria segetalis, showing estrogen-like activity, were determined by the distance geometry calculation and restrained energy minimization from NMR data. The backbone structure of segetalin G contains one β-turn: a β II-like turn at Tyr4-Ala5, and that of segetalin H one β-turn: a β II′ turn at Gly1-Tyr2 and one γ-turn at Arg3-Phe4-Ser5 sequence. The results of distance comparison analysis proposed a pharmacophore model of estrogen-like cyclic peptides, segetalins.