C‐Ring Aromatized Abietane Diterpenoids From <i>Lycopus lucidus</i>

The phytochemical research of the extract of Lycopus lucidus led to 12 aromatic C-ring abietane diterpenoids (1-12), including three new structures (1-3) obtained. The structures including absolute configurations of the new compounds were elucidated via high-resolution electrospray ionization mass spectrometry and nuclear magnetic resonance, combined with the electronic circular dichroism calculations. Among them, compound 1 is a rare 17-norditerpenoid, and compound 2 is a 19-norditerpenoid. Moreover, compound 3 is a rearranged 18(4→3)-abeo-abietane diterpenoid. The bioassay results showed that new compound 3 exhibited potential cytotoxicity on HEL cells, with a half-maximal inhibitory concentration (IC₅₀) value of 14.59 ± 0.55 µM. Besides, compound 9 showed remarkable inhibitory activities against HEL cells, with the IC₅₀ value of 0.93 ± 0.11 µM (stronger than that of the positive control, doxorubicin, IC₅₀ = 0.95 ± 0.12 µM). Furthermore, the flow cytometry revealed that compound 9 exerts an anti-tumor effect and should be related to inducing HEL cell apoptosis.