Abiesanordines A–N: fourteen new norditerpenes from Abies georgei

Fourteen new norditerpenoids (abiesanordines A–N, 1–14), including a novel podocarpene bearing a rare enolic structure (abiesanordine A, 1), were isolated from Abies georgei together with eight known ones. Their structures were determined mainly by detailed analysis of 1D and 2D NMR spectroscopic data including HSQC, DQF COSY, HMBC, and NOESY. All the isolates were tested for inhibitory activities against LPS-induced NO production in RAW264.7 macrophages, abiesanordine I (9) showed the strongest activity with the IC50 value of 17.0 μg/mL. Furthermore, it exhibited no cytotoxicity against RAW264.7 macrophages under the concentration of 50 μg/mL.