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Eight previously undescribed sesquiterpene lactones (1 – 8), together with six known ones (9 – 14) were isolated from the aerial parts of Tithonia diversifolia (Hemsl.) A. Gray. The absolute configurations of these compounds were elucidated using HRMS, NMR spectroscopy, optical rotation measurements, X-ray crystallography, and ECD. Among them, sesquiterpene lactones 2 – 4 share a unique carbon skeleton with a rare C-3/C-4 ring-opened structure. Compounds 1 and 8 showed moderate inhibitory effects toward CT26 murine colon carcinoma cells by promoting lipid ROS production, highlighting their potential as ferroptosis inducers. [Display omitted] • Eight undescribed sesquiterpene lactones were isolated from Tithonia diversifolia. • 2 – 4 were 3,4-seco-sesquiterpene lactones. • 1 and 8 could promote lipid ROS production, acting as new ferroptosis inducers. [ABSTRACT FROM AUTHOR]

Thirteen previously undescribed iridoids (1 – 13), together with five known iridoids (14 – 18) were isolated from the roots and rhizomes of Valeriana jatamansi Jones. Their structures with absolute configurations were elucidated by analysis of MS, NMR, optical rotation and their experimental and calculated electronic circular dichroism spectra. All of the isolated compounds were tested for their protective effects against α-hemolysin-induced cell death in A549 cells. Compounds 14 , 16 and 17 showed moderate protective effects, and compounds 15 and 18 showed weak protective effects. Eighteen iridoids including thirteen previously undescribed ones were isolated from Valeriana jatamansi Jones and some of them exhibited protective effects against α-hemolysin-induced cell death in A549 cells. [Display omitted] • Thirteen previously undescribed iridoids were isolated from Valeriana jatamansi. • Compounds 1 and 2 were unique iridoids with isovaleroxy at C-1 and C-3. • Compounds 14 , 16 and 17 showed moderate protective effects against α-hemolysin. [ABSTRACT FROM AUTHOR]