Exploring the Bioactive Terpenoid Content of an Algerian Plant of the Genus Pulicaria: The ent-Series of Asteriscunolides

Chemical analysis of the chloroform extract of the aerial parts of the Algerian plant Pulicaria undulata exhibiting anti-inflammatory activity resulted in the isolation of 10 new humulene sesquiterpenoids, 1-10, belonging to the asteriscunolide family of compounds. The structure and relative configuration have been defined by NMR data, whereas the absolute configuration has been established by ECD analysis. Compounds 1-10 include enantiomers of the known asteriscunolides A-D and tetrahydroasteriscunolide previously reported from the genera Asteriscus and Nauplius. Compounds 1 and 10 showed in vitro anti-inflammatory activity by inhibiting heat-induced albumin denaturation with IC50 values of 23.76 and 220.42 mu M.