Halimane and labdane diterpenoids from Leonurus japonicus and their anti-inflammatory activity

Ten highly oxygenated diterpenoids (nine undescribed ones) were isolated from the aerial parts of Leonurus japonicus Houtt. 14,15-Dinor-labd-5,8-dien-3,13-dione was a 14,15-dinor-labdane diterpenoid possessing a C18 skeleton. 7β,9α-Dihydroxy-6-oxo-labd-13-en-15,16-amide represented a rare example of labdane diterpenoid featuring an α,β-unsaturated-γ-lactam moiety. The structures of all compounds were elucidated using spectroscopic data analyses...