Isopimarane Diterpenoids from the Rhizomes of Kaempferia marginata and Their Potential Anti-inflammatory Activities

Six new isopimarane diterpenes, marginaols A–F (1–6), along with eight known compounds (7–14), were isolated from the rhizomes of Kaempferia marginata. The structures and absolute configurations of 1–6 were established on the basis of spectroscopic methods and the experimental and calculated ECD data as well as comparison with the literature values. Most of the isolated compounds were tested for their nitric oxide (NO) inhibitory effects in lipopolysaccharide-activated RAW264.7 cells. Among them, marginaol B (2) was found to reduce NO levels in murine macrophage cells with an IC50 value of 28.1 ± 1.7 μM.