Revisiting diterpene lactones of Suregada multiflora

Phytochemical investigations on the organic extracts of the leaves of Suregada multiflora have led to the isolation of ten tetracyclic diterpene lactones , members of a rare class of abiatene diterpene lactones. Compounds were found to be new. The structures of gelomulides (), () and () were revised on the basis of 2D NMR and X-ray diffraction evidences. Compounds and contain an epoxy linkage between C-8 and C-14, whereas compounds were identified as 8,14-dihydroxy analogues of diterpene lactones. The stereochemical assignments in new compound are based on X-ray diffraction analysis. Compounds and were identified as the known gelomulides , . The structures of compounds were unambiguously confirmed by X-ray diffraction analyses.