Daphnane diterpenoids from the stems of Trigonostemon lii and their anti-HIV-1 activity

Thirteen highly oxygenated daphnane diterpenoids, including six known compounds, were isolated from the stems of Trigonostemon lii. The structures were elucidated by extensive spectroscopic analyses including 2D NMR spectroscopy (HSQC, (1)H-(1)H COSY, HMBC, and ROESY) and mass spectrometry. The absolute stereochemistries of compounds were established on the basis of CD spectra. Four of the compounds showed modest anti-HIV-1 activity (EC50=2.04, 9.17, 11.42, and 9.05 μg/ml, TI=26.49, >21.81, 9.32, and 9.56, respectively) in vitro.