Sesquiterpenoids with various carbocyclic skeletons from Nardostachys chinensis with nitric oxide inhibitory activity

Chemical investigation on the roots and rhizomes of Nardostachys chinensis Batal led to the isolation of twenty-one sesquiterpenoids with various carbocyclic skeletons including three eudesmane-type (1-2, 4), nine nardosinane-type (3, 5-12), and nine aristolane-type sesquiterprenoids (13-21). The structures of the new compounds 1 and 3, and the new natural product 2 were established by extensive spectroscopic analysis, and their absolute configurations were established by computational electronic circular dichroism (ECD) method. Nitric oxide (NO) is one of the most important inflammatory modulators in many inflammatory diseases. Thus, inhibitory effects of compounds 1-21 on NO production were investigated in lipopolysaccaride (LPS)-mediated RAW 264.7 cells, and compounds 13-15 displayed NO inhibitory activity with IC50 values of 2.67, 2.79, 9.87 μM, respectively. Moreover, a further study revealed that compound 13 exhibited anti-inflammatory activity via suppression of IL-6, IL-10, and IL-23.