This study aims to investigate the diterpenoids of Tinosporae Radix and their anti-inflammatory activity.Various chromatographic techniques were used for isolation of the ethanol extract of Tinosporae Radix.The structures of the compounds were identified using MS,NMR,CD,and single X-ray crystal diffraction.The Griess method was used to determine the inhibitory activity of the compounds on the production of nitric oxide (NO) in lipopolysaccharide-induced BV2 cells.Seven clerodane diterpenoids were isolated from the EtOAc part of the ethanol extract of Tinosporae Radix,including tinocapill A (1),tinocapill B (2),crispene A (3),floridolide B (4),columbin (5),tinosporol B (6) and borapetol A (7).Compounds 1 and 2 were new compounds,while the activity results indicated that compounds 2 and 6 could significantly inhibit LPS-induced NO release in murine BV2 cells (with IC₅₀ values of 9.6 and 5.8 μmol/L,respectively),showing potential anti-inflammatory activity.