New diterpenoid alkaloids from Delphinium pachycentrum Hemsl.

Six diterpenoid alkaloids, namely, pachycentine ( 1 ), deacetylswinanine A ( 2 ), siwanine A ( 3 ), tatsiensine ( 4 ), deacetyltatsiensine ( 5 ), and 6-deoxydeltamine ( 6 ), were isolated from a China-specific Delphinium plant (family Ranunculaceae), Delphinium pachycentrum Hemsl. Their structures were established via detailed spectroscopic analyses, including IR, HR-ESI-MS, 1D and 2D NMR techniques. Pachycentine ( 1 ) is a previously undescribed hetisine-type C 20 -diterpenoid alkaloid, and compounds 5 and 6 were synthetic intermediates newly identified as natural products. In addition, compounds 2 - 4 were isolated from this species for the first time. The chemotaxonomic significance of all the isolates was summarized. Moreover, the new compound was evaluated for its potential anti-inflammatory effect using LPS-stimulated RAW 264.7 macrophages.