Neo-clerodane diterpenoids from the whole plants of Scutellaria formosana.

Scuteformoids A-J, ten previously undescribed neo-clerodane diterpenoids along with one known analogue, were isolated from petroleum ether soluable fraction of the whole plants of Scutellaria formosana. The differences among these compounds are the substituents and stereochemistry at C-13. Their structures were elucidated by 1D and 2D NMR experiments, and the absolute configurations of Scuteformoids A, C, E, F, and I were further confirmed by single-crystal X-ray diffraction. Scuteformoids A, C, D, F, H, and I were evaluated for their inhibitory effects against HIV lytic replication and cytotoxic activities. All of them showed weak anti-HIV activities, with EC50 values ranging from 48.24 to 79.17 μg/mL.