Abietane diterpenoids from Orthosiphon wulfenioides with NLRP3 inflammasome inhibitory activity.

Wulfenioidones A - K (1-11) were abietane diterpenoids with highly oxidized 6/6/6 aromatic tricyclic skeleton isolated from the whole plant of Orthosiphon wulfenioides, and their planar structures and absolute configurations were elucidated by spectroscopic data interpretation, electronic circular dichroism calculation as well as X-ray crystallography analysis. Bioactivity screening indicated that compounds 1-4, 6 and 8 exhibited lactate dehydrogenase (LDH) inhibition effect with IC50 values ranging from 0.23 to 3.43 µM by preventing the mononuclear macrophage cell pyroptosis induced by double signal stimulation of LPS and nigericin. Western Blot analyses of Caspase-1 and IL-1ß down-regulation exhibited that compound 1 could selectively inhibit NLRP3 inflammasome, and the cell morphological observation further supported that compound 1 prevented macrophage cell pyroptosis.