Diterpenoids from the Roots of Suregada glomerulata

Six new diterpenoids, 7β,8α-dihydroxy-12-oxo-ent-abietan-16,14-olide (1), 3,4,18β-cyclopropa-7β,17-dihydroxy-ent-abieta-8(14),13(15)-dien-16,12-olide (2), 3α,7β-dihydroxy-ent-abieta-8(14),13(15)-dien-16,12-olide (3), 3-oxo-8β,14β-epoxy-ent-abieta-11,13(15)-dien-16,12-olide (4), 17-hydroxy-ent-pimara-8(14),15-dien-3-one (5), and 3α,6β-dihydroxy-ent-kaur-16-ene (6), and two known compounds, 7β-hydroxy-ent-abieta-8(14),13(15)-dien-16,12-olide (7) and jolkinolide B, were isolated from roots of Suregada glomerulata. The structures of the new compounds were elucidated on the basis of 1D and 2D NMR and other spectroscopic studies. The structure of compound 1 was confirmed by X-ray crystallography. Cytotoxic activities were evaluated against five human tumor cell lines.