Neomerane-type sesquiterpenoids from Valeriana officinalis var. latifolia

Valeneomerins A–D, two new neomerane-type sesquiterpenoids and two new nor-sesquiterpenoids, were isolated from the roots of Valeriana officinalis var. latifolia. Among them, valeneomerin A (1) was identified as a sesquiterpenoid with an unprecedented 15,3-lactone loop while valeneomerin C (3) and valeneomerin D (4) were determined to be nor-sesquiterpenoids with a new 15-reductive neomerane-type carbon skeleton. Their structures were elucidated by detailed spectroscopic analysis and Cu Kα X-ray crystallography. Compounds 1, 2, and 4 exhibited significant neuroprotective effects against H2O2 induced oxidative stress in SH-SY5Y cells with viability of 49.8, 40.9, and 44.6% each at 50 μM, respectively, in contrast to positive control (catechin, 50 μM) with viability of 32.6%.