Bioactive 3,8‐Epoxy Iridoids from Valeriana jatamansi

: Twelve 3,8-epoxy iridoids, including four new compounds, jatamanins R-U (1-4), and eight known compounds (5-12), were obtained from the roots and rhizomes of Valeriana jatamansi. The structures were elucidated from analysis of spectroscopic data. The absolute configurations of 1-4 were determined by comparison of experimental and literature ECD spectra. Moreover, the compounds were evaluated for cytotoxic effects against glioma stem cells, inhibition of NO production, activity against influenza A virus and reversal of multidrug resistance of HepG2/ADR cells. Compounds 9 and 12 showed significant cytotoxic potency against GSC-18# (IC50 =1.351 and 4.439 μg ml-1 , respectively) and GSC-3# (IC50 =10.88 and 6.348 μg ml-1 , respectively) glioma stem cells, while compound 12 was also slightly less potent against GSC-12# (IC50 =13.45 μg ml-1 ) glioma stem cell growth. In addition, compounds 9 and 12 displayed obvious inhibition of NO production (IC50 =4.6 and 15.8 μm, respectively).