Diterpenoids from the aerial parts of Isodon serra and their anti-hepatocarcinoma potential

Abstract

Three new ent-kaurane diterpenoids, isodosins E–G (1–3), along with 20 known ones (4–23), were obtained from the aerial parts of Isodon serra (Maxim.) Hara. The structures of the new compounds were elucidated using 1D/2D NMR spectra and HREIMS data, and their absolute configurations were determined by electronic circular dichroism (ECD) calculations. The in vitro anti-hepatocarcinoma activities of compounds 2, 3, 5, 8, 13, 19, and 23 were evaluated against HepG2 and Huh7 cell lines using the CCK-8 assay. Among them, compounds 3, 8, and 23 exhibited high inhibitory effects on HepG2 cells, with IC₅₀ values of 6.94 ± 9.10 μM, 71.66 ± 10.81 μM, and 43.26 ± 9.07 μM, respectively. In a Hepa1-6 xenograft mouse model, compound 8 significantly inhibited tumor growth at doses of 50 and 100 mg kg⁻¹, demonstrating its potent anti-hepatocarcinoma activity.