Grandisine A and B, novel indolizidine alkaloids with human delta-opioid receptor binding affinity from the leaves of the Australian rainforest tree Elaeocarpus grandis.

Two novel indolizidine alkaloids, grandisine A (1) and B (2), and the known alkaloid (-) isoelaeocarpiline (3) were isolated from the leaves of Elaeocarpus grandis and their structures determined by 1D and 2D NMR spectroscopy. The compounds showed affinity for the human delta-opioid receptor. Grandisine A contains a unique tetracyclic skeleton, while grandisine B possesses the unique combination of isoquinuclidinone and indolizidine groups in one molecule.