Isolation and structure characterization of two new diterpenoids from Clerodendrum bungei

Two new diterpenoids, 3β-(β-d-glucopyranosyl)isopimara-7,15-diene-11α,12α-diol (1), and 16-O-β-d-glucopyranosyl-3β-20-epoxy-3-hydroxyabieta-8,11,13-triene (2), along with three known ones were isolated from the roots of Clerodendrum bungei. These compounds were purified, and their structures were elucidated by extensive spectroscopic analyses, especially 2D NMR experiments. All compounds were evaluated for cytotoxicity against several tumor cell lines.