Bioactive Iridoid Glycosides from the Whole Plants of Rehmannia chingii

Nine new iridoid glycosides, rehmachingiiosides A–I (1–9), together with 16 known analogues, were isolated from the whole plants of Rehmannia chingii. The structures of compounds 1–9 were elucidated on the basis of spectroscopic data analysis and from chemical evidence. Furthermore, in two vitro assays, compounds 5 and 10 showed an inhibitory effect on LPS-induced NO production with IC₅₀ values of 2.5 and 7.3 μM, and compounds 4, 6, and 10–12 (when evaluated at 10 μM) exhibited evidence of hepatoprotective effects against APAP-induced HepG2 cell damage.