New bis-β-triketone-sesquiterpene adducts from Corymbia citriodora with lysosomal biogenesis-inducing activity.

Corymbistriodones A-E (1-5), five unprecedented bis-β-triketone-sesquiterpene adducts (BTSAs) were isolated from Corymbia citriodora. The absolute configurations of these compounds were determined by comprehensive spectroscopic analysis, electronic circular dichroism (ECD) calculations, and X-ray crystallography. Corymbistriodone A (1) represent a new subclass of meroterpenoids, characterized by a rare oxa-spiro [5.6] unit and feature a unique 6/6/7/3/5-6 fused hexacyclic ring system. Compounds 2-5 are new skeletal BTSAs with unusual coupling pattern between dual isopentylsyncarpic acid and bicyclogermacrene. Corymbistriodone D (4) was found to induce TFEB- and TFE3-mediated lysosomal biogenesis.