Volvalerelactones A and B, Two New Sesquiterpenoid Lactones with an Unprecedented Skeleton from Valeriana officinalis var. latifolia

Volvalerelactones A and B (1 and 2), two new sesquiterpenoid lactones with an unprecedented 3/7/6 tricyclic ring system, were isolated from the roots of Valeriana officinalis var. latifolia. Their structures and relative configurations were elucidated by spectroscopic data and single-crystal X-ray diffraction crystallography, and the absolute configuration was assigned by computational methods. The possible biosynthetic pathways of 1 and 2 were also proposed.