Chemical constituents from Vernonia bockiana

A new sesquiterpenoid and two pregnane steroids, named vernobockolide C ( 1 ) and vernobockones A and B ( 2 and 3 ), respevtively, along with a known sesquiterpenoid, 7, 10-epoxy-11-hydroxy-bisabol-2-en-15-al, were isolated from the aerial part of Vernonia bockiana. Their structures were elucidated on the basis of extensive spectroscopic data analysis, especially 2D NMR (HSQC, HMBC, and ROESY). This study further expands the chemical space of this underexplored species.