Structurally Diverse Labdane Diterpenoids from and Their Anti-inflammatory Properties in LPS-Induced RAW264.7 Cells.

A phytochemical study on the aerial parts of led to the isolation and identification of 38 labdane diterpenoids, including 18 new (, , , , -, , -, , ) and 20 known (-, -, , , -, , ) analogues. Their structures were elucidated based on physical data analysis, including 1D and 2D NMR, HRMS, UV, IR, and X-ray diffraction. The structure of the known compound was confirmed by single-crystal X-ray diffraction data. These compounds can be divided into furanolabdane (-), tetrahydrofuranolabdane (-), lactonelabdane (-), labdane (-), and -labdane (-) type diterpenoids. All compounds were screened by lipopolysaccharide (LPS)-induced nitric acid (NO) production in RAW264.7 cells to evaluate anti-inflammatory effects. Compounds , , -, -, -, and inhibited NO production with IC values lower than 50 μM, with compound being the most active, with an IC value of 3.9 ± 1.7 μM. Further studies show that compound inhibits pro-inflammatory cytokine production and IKK α/β phosphorylation and restores the IκB expression levels in the NF-κB signaling pathway.