Dammarane-Type Triterpenoids from Gentianella azurea

Thirteen new dammarane-type triterpenoids (1-13) and four known analogues, gentirigenic acid (14) and the gentirigeosides A, B, and E (15-17), were isolated from Gentianella azurea. Their structures were elucidated by detailed analysis of the NMR, MS, and X-ray crystallographic data. This is the first report of dammarane-type triterpenoids in the Gentianella genus. In addition, the known structures of gentirigenic acid (14) and the gentirigeosides A, B, and E (15-17) were revised based on the X-ray diffraction analysis. Gentirigeoside A (15) was found to inhibit nitric oxide production in RAW 264.7 macrophages with an IC50 value of 6.6 +/- 2.1 mu M.