Antitubercular and cytotoxic tigliane-type diterpenoids from Croton tiglium.

Five new tigliane diterpene esters (1-5), highly oxygenated tetracyclic diterpenoid carbon skeleton, together with three known analogues (6-8) were isolated from the leaves of Croton tiglium. Extensive NMR and mass spectroscopic analysis were used to elucidate their structures. Most of the isolated compounds were tested for their cytotoxic and antitubercular activities. Among them, the cytotoxic activities of these tigliane-type diterpenes strongly depend on the species of the tumor cells. Especially, these bioactivity compounds showed strong cytotoxic activities against the K562 cell line, and their inhibition effects were close to the positive control Taxol. Furthermore, compounds 1, 2, 6, and 7 showed potent antitubercular activities with MIC values of 19.5, 20.9, 20.5, and 13.4µM, respectively.

Dicarabrol, a new dimeric sesquiterpene from Carpesium abrotanoides L.

A new dimeric sesquiterpene, dicarabrol (1), together with three known sesquiterpenes, carabrol (2), 11(13)-dehydroivaxillin (3), and 2-desoxy-4-epi-pulchellin (4), were isolated from the whole plant of Carpesium abrotanoides L. Their structures were elucidated on the basis of spectroscopic analysis, and single crystal X-ray diffraction analysis. Compound 1 possessed a dimeric sesquiterpene core featured with a cyclopentane ring connecting two sesquiterpene lactone units rarely discovered in nature. Dicarabrol (1), as well as three known sesquiterpenes (2-4), had potent in vitro cytotoxicities against the K562, MCF-7, Hela, DU145, U937, H1975, SGC-7901, A549, MOLT-4, and HL60 cell lines with IC50 values ranging from 0.10 to 46.7 µM, while they showed significant antiviral (H1N1 and H3N2) activities. Furthermore, compounds 1, 3 and 4 displayed significant antimycobacterial activity (IC50 3.7, 6.0, and 7.6 µM, respectively).