Young Sook Yun

Segetalin A, a new cyclic hexapeptide from vaccaria segetalis

Abstract A new cyclic hexapeptide, segetalin A, showing estrogen-like activity, has been isolated from the seeds of Vaccaria segetalis and the structure was elucidated by extensive 2D NMR, chemical and enzymatic degradations and ESI-MS/MS methods.

Segetalins B, C and D, three new cyclic peptides from Vaccaria segetalis☆

Abstract Three new cyclic peptides, segetalins B, C and D, were isolated from Vaccaria segetalis (seeds) and their structures were elucidated by 2D NMR and chemical degradations. Conformational analysis of segetalin B, having an estrogen-like effect, was made by using high field NMR and computational methods. Segetalin B was suggested to possess a solution conformation similar to that of segetalin A in the region of Trp-Ala-Gly-Val. The sequence and conformation of Trp-Ala-Gly-Val may play an important role to show the activity.

Conformational analysis of a cyclic hexapeptide, segetalin A from Vaccaria segetalis

Abstract To establish a pharmacophore model, conformation in solid and solution states of a cyclic hexapeptide, segetalin A, having an estrogen-like activity, was investigated by a combination of X-ray analysis, high field NMR and computational chemical evidence. The three-dimensional structure of crystalline segetalin A was characterized by two β-turn structures, one being of type I and the other of type VI, fixed by the two trans-annular hydrogen bonds formed between the 1st Gly and the 4th Val. On the other hand, in solution, the molecule was shown to have two β-turn structures, one being of type II and the other of type VI, by NMR and MD calculation, demonstrating that segetalin A takes different backbone conformations in solid and solution states.

A cyclic heptapeptide from Vaccaria segetalis

A new cyclic heptapeptide, segetalin E, cyclo(-Gly-Tyr-Val-Pro-Leu-Trp-Pro-), has been isolated from the seeds of Vaccaria segetalis and the structure elucidated by extensive two-dimensional NMR methods and chemical degradation.

Vaccaroid A, a new triterpenoid saponin with contractility of rat uterine from Vaccaria segetalis

Abstract Vaccaroid A, a new triterpenoid saponin, showing uterine contraction, has been isolated from the seeds of Vaccaria segetalis and its structure was elucidated to be 3β-hydroxyolean-12-en-23, 28-dioic acid-28- O - β -D-glucopyranosyl-(1→3)- β -D-glucopyranosyl-(1→6)-[ β -D-glucopyranosyl-(1→2)]- β -D-glucopyranoside by using a combination of extensive 2D NMR techniques.

Thionation of segetalins A and B, cyclic peptides with estrogen-like activity from seeds of Vaccaria segetalis

Thionation of estrogen-like active cyclic peptides, segetalins A (1) and B (2), with Lawessons reagent provided each two thiosegetalins; thiosegetalin A1 [Gly-1-psi(CS-NH)-Val-2; Trp-5-psi (CS-NH)-Ala-6]segetalin A, thiosegetalin A2 [Gly-1-psi(CS-NH)-Val-2; Ala-6-psi(CS-NH)-Gly-1]segetalin A, thiosegetalin B1 [Gly-1-psi (CS-NH)-Val-2; Ala-3-psi(CS-NH)-Trp-4]segetalin B, and thiosegetalin B2 [Gly-1-psi(CS-NH)-Val-2; Trp-4-psi(CS-NH)-Ala-1]segetalin B. Thiosegetalin A2 only showed estrogen-like activity against ovariectomized rats. On the basis of their conformations analysed by NMR experiments, the backbone conformation was considered to play an important role in estrogen-like activity for segetalins.

Triterpenoid saponin from Vaccaria segetalis

A new triterpenoid saponin, vaccaroid B, has been isolated from the seeds of Vaccaria segetalis and its structure was elucidated to be 3beta-hydroxyolean-12-en-23, 28-dioic acid-28-O-beta-D-glucopyranosyl-(1-->3)- beta-D-glucopyranosyl-(1-->6)-[6- O-(3-hydroxy-3-methylglutaryl)-beta-D-glucopyranosyl-(1-->2)]- beta-D-glucopyranoside by spectroscopic methods.

A new bis-seco-abietane diterpenoid from Hyptis crenata Pohl ex Benth.

A new, highly oxidized, bis-seco-abietane diterpenoid named hyptisolide A (1) was isolated from Hyptis crenata Pohl ex Benth. Its structure and stereochemistry were elucidated on the basis of data obtained by HRESIMS, NMR, and X-ray diffraction analyses, and its absolute configuration was determined with vibrational circular dichroism spectroscopy. By reporter gene assay, 1 was demonstrated to induce cAMP-responsive element-dependent transcription in Neuro2A cells.