Anti-inflammatory abietanes diterpenes and triterpenoids isolated from Clinopodium polycephalum.

Two previously undescribed diterpenes (1 and 2), as well as one curious triterpenoid were isolated from Clinopodium polycephalum , a medicinal plant distributed in southwestern and eastern China. Their structures were elucidated using MS analyses, UV spectrum, and extensive 2D-homo and heteronuclear NMR data interpretations. Among them, 1 had an unusual skeletal characteristic produced by a rare methyl migration pathway. All monomer compounds exhibited inhibitory effects on NO production in LPS-induced RAW 264.7 cells without affecting cell viabilities, which were comparable to that of positive control. [Display omitted] • Three new (1 – 3) and five known compounds were isolated from Clinopodium polycephalum. • Structures were characterized by 1D and 2D NMR, HRESIMS, ECD analysis and DP4+ analysis. • Compounds 1 – 8 exhibited a significant inhibitory effect against NO production in LPS-stimulated RAW 264.7 macrophages. • The hypothetical biosynthetic pathway for compound 1 was proposed. [ABSTRACT FROM AUTHOR]