Bioactive norditerpenoids from Flickingeria fimbriata

Abstract

Seven new degraded diterpenoids (1–6 and 11), four new ent-pimarane type diterpenoids (7–10) and a known analogue (12) were isolated from the stem of Flickingeria fimbriata. Compounds 1–4, namely norflickinflimiods A–D, possessed a rare 16-nor-ent-pimarane skeleton, and 5–6, namely norflickinflimiods E and F, represented an unusual skeleton of 15,16-dinor-ent-pimarane. The structures including the absolute configurations of 1–12 were elucidated using spectroscopic analysis, single-crystal X-ray diffraction, computational methods, and chemical correlations. All the isolates were screened for anti-inflammatory and antitumor activities, and compounds 5, 6, 9, and 12 showed potent inhibitory activities against lipopolysaccharide (LPS)-induced TNF-α production in RAW264.7 cells with IC₅₀ values less than 10 μM, while compounds 8–11 exhibited cytotoxicity against MCF-7 cells (9.6, 9.0, 12.0, and 15.6 μM).