neo-Clerodane Diterpenoids from the Aerial Parts of Scutellaria barbata with Anti-Inflammatory Activity.

The bioactivity-guided isolation on the Scutellaria barbata extract resulted in the purification of four undescribed neo-clerodane diterpenoids, scuttenlines A-D (1-4), alone with 20 known diterpenoids (5-24). The chemical structures of them were elaborated by extensive spectroscopic means, including 1D, 2D-NMR and HR-MS. The anti-inflammatory potential ability of 1-24 was screened in lipopolysaccharide-stimulated mouse RAW 264.7 cells. Scuttenline C (IC50 =1.9 µM) and 18 (IC50 =3.7 µM) exhibited potent activity to inhibit NO production.