American Chemical Society
np9005579_si_003.cif (20.79 kB)

ent-Kaurane and ent-Pimarane Diterpenoids from Siegesbeckia pubescens

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posted on 2010-01-22, 00:00 authored by Rui Wang, Wen-Hao Chen, Yan-Ping Shi
Phytochemical investigation of the above-ground parts of Siegesbeckia pubescens yielded 25 diterpenoids, including five new ent-pimarane diterpenoids (13, 11, and 12) and four new ent-kaurane diterpenoids (1316). The structures and relative configurations of the new compounds were elucidated by comprehensive spectroscopic analysis and by comparison of their NMR data with those of related compounds. Single-crystal X-ray diffraction analysis confirmed the structures of 8, 13, and 14. Seven of these diterpenoids were evaluated for cytotoxic activity against HSC-T6, HeLa, and B16 cell lines. Compounds 11 and 14 exhibited moderate cytotoxicity.