Ptehosides A-I: Nine undescribed iridoids with in vitro cytotoxicity from the whole plant of Pterocephalus hookeri (C.B. Clarke) Höeck.

Nine previously undescribed iridoids, ptehosides A-I (1 – 9), together with 12 known ones (10 – 21), were isolated from Pterocephalus hookeri (C.B. Clarke) Höeck. Their structures were elucidated using various spectroscopic methods including HR-ESI-MS, NMR, UV, IR and CD, etc. The cytotoxic activities of all isolates were evaluated using MTT method in three human cancer cell lines (Caco2, Huh-7, and SW982). As result, compound 9 exhibited substantial inhibitory activity on Caco2, Huh-7, and SW982 cells with IC 50 values of 1.17 ± 0.05, 1.15 ± 0.05 and 1.14 ± 0.04 μM, respectively. A preliminary mechanism study showed that 9 arrested the cell cycle of SW982 cells in the G0/G1 phase and induced apoptosis by upregulating Bax expression and downregulating Bcl-2 expression. Nine undescribed iridoids, together with twelve known ones were isolated from the whole plant of Pterocephalus hookeri. Among them, seven compounds showed significant cytotoxic activities against SW982 cells in vitro. Mechanically, ptehoside I (9) could arrest the cell-cycle in G0/G1 phase and induce apoptosis. [Display omitted] • Nine undescribed iridoids were isolated from the whole plant of Pterocephalus hookeri. • The stereochemistry was identified by acid hydrolysis, experimental and calculated ECD. • Ptehoside I (9) induced G0/G1 cell cycle arrest against SW982 cells in vitro. • 9 induced apoptosis and regulated the expression levels of Bax and Bcl-2 proteins in SW982 cells. [ABSTRACT FROM AUTHOR]